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Subject[PATCH 2/8] lguest: the host code
From
Date
This is the code for the "lg.ko" module, which allows lguest guests to
be launched.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
drivers/lguest/core.c | 444 +++++++++++++++++++++++++++++++++
drivers/lguest/hypercalls.c | 172 ++++++++++++
drivers/lguest/interrupts_and_traps.c | 258 +++++++++++++++++++
drivers/lguest/io.c | 412 ++++++++++++++++++++++++++++++
drivers/lguest/lg.h | 278 ++++++++++++++++++++
drivers/lguest/lguest_user.c | 192 ++++++++++++++
drivers/lguest/page_tables.c | 407 ++++++++++++++++++++++++++++++
drivers/lguest/segments.c | 115 ++++++++
drivers/lguest/switcher.S | 159 +++++++++++
include/linux/lguest_launcher.h | 80 +++++
10 files changed, 2517 insertions(+)
===================================================================
--- /dev/null
+++ b/drivers/lguest/core.c
@@ -0,0 +1,444 @@
+/* World's simplest hypervisor, to test paravirt_ops and show
+ * unbelievers that virtualization is the future. Plus, it's fun! */
+#include <linux/module.h>
+#include <linux/stringify.h>
+#include <linux/stddef.h>
+#include <linux/io.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <linux/cpu.h>
+#include <linux/freezer.h>
+#include <asm/paravirt.h>
+#include <asm/desc.h>
+#include <asm/pgtable.h>
+#include <asm/uaccess.h>
+#include <asm/poll.h>
+#include <asm/highmem.h>
+#include <asm/asm-offsets.h>
+#include <asm/i387.h>
+#include "lg.h"
+
+/* Found in switcher.S */
+extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];
+extern unsigned long default_idt_entries[];
+
+/* Every guest maps the core switcher code. */
+#define SHARED_SWITCHER_PAGES \
+ DIV_ROUND_UP(end_switcher_text - start_switcher_text, PAGE_SIZE)
+/* Pages for switcher itself, then two pages per cpu */
+#define TOTAL_SWITCHER_PAGES (SHARED_SWITCHER_PAGES + 2 * NR_CPUS)
+
+/* We map at -4M for ease of mapping into the guest (one PTE page). */
+#define SWITCHER_ADDR 0xFFC00000
+
+static struct vm_struct *switcher_vma;
+static struct page **switcher_page;
+
+static int cpu_had_pge;
+static struct {
+ unsigned long offset;
+ unsigned short segment;
+} lguest_entry;
+
+/* This One Big lock protects all inter-guest data structures. */
+DEFINE_MUTEX(lguest_lock);
+static DEFINE_PER_CPU(struct lguest *, last_guest);
+
+/* FIXME: Make dynamic. */
+#define MAX_LGUEST_GUESTS 16
+struct lguest lguests[MAX_LGUEST_GUESTS];
+
+/* Offset from where switcher.S was compiled to where we've copied it */
+static unsigned long switcher_offset(void)
+{
+ return SWITCHER_ADDR - (unsigned long)start_switcher_text;
+}
+
+/* This cpu's struct lguest_pages. */
+static struct lguest_pages *lguest_pages(unsigned int cpu)
+{
+ return &(((struct lguest_pages *)
+ (SWITCHER_ADDR + SHARED_SWITCHER_PAGES*PAGE_SIZE))[cpu]);
+}
+
+static __init int map_switcher(void)
+{
+ int i, err;
+ struct page **pagep;
+
+ switcher_page = kmalloc(sizeof(switcher_page[0])*TOTAL_SWITCHER_PAGES,
+ GFP_KERNEL);
+ if (!switcher_page) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ for (i = 0; i < TOTAL_SWITCHER_PAGES; i++) {
+ unsigned long addr = get_zeroed_page(GFP_KERNEL);
+ if (!addr) {
+ err = -ENOMEM;
+ goto free_some_pages;
+ }
+ switcher_page[i] = virt_to_page(addr);
+ }
+
+ switcher_vma = __get_vm_area(TOTAL_SWITCHER_PAGES * PAGE_SIZE,
+ VM_ALLOC, SWITCHER_ADDR, VMALLOC_END);
+ if (!switcher_vma) {
+ err = -ENOMEM;
+ printk("lguest: could not map switcher pages high\n");
+ goto free_pages;
+ }
+
+ pagep = switcher_page;
+ err = map_vm_area(switcher_vma, PAGE_KERNEL, &pagep);
+ if (err) {
+ printk("lguest: map_vm_area failed: %i\n", err);
+ goto free_vma;
+ }
+ memcpy(switcher_vma->addr, start_switcher_text,
+ end_switcher_text - start_switcher_text);
+
+ /* Fix up IDT entries to point into copied text. */
+ for (i = 0; i < IDT_ENTRIES; i++)
+ default_idt_entries[i] += switcher_offset();
+
+ for_each_possible_cpu(i) {
+ struct lguest_pages *pages = lguest_pages(i);
+ struct lguest_ro_state *state = &pages->state;
+
+ /* These fields are static: rest done in copy_in_guest_info */
+ state->host_gdt_desc.size = GDT_SIZE-1;
+ state->host_gdt_desc.address = (long)get_cpu_gdt_table(i);
+ store_idt(&state->host_idt_desc);
+ state->guest_idt_desc.size = sizeof(state->guest_idt)-1;
+ state->guest_idt_desc.address = (long)&state->guest_idt;
+ state->guest_gdt_desc.size = sizeof(state->guest_gdt)-1;
+ state->guest_gdt_desc.address = (long)&state->guest_gdt;
+ state->guest_tss.esp0 = (long)(&pages->regs + 1);
+ state->guest_tss.ss0 = LGUEST_DS;
+ /* No I/O for you! */
+ state->guest_tss.io_bitmap_base = sizeof(state->guest_tss);
+ setup_default_gdt_entries(state);
+ setup_default_idt_entries(state, default_idt_entries);
+
+ /* Setup LGUEST segments on all cpus */
+ get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
+ get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
+ }
+
+ /* Initialize entry point into switcher. */
+ lguest_entry.offset = (long)switch_to_guest + switcher_offset();
+ lguest_entry.segment = LGUEST_CS;
+
+ printk(KERN_INFO "lguest: mapped switcher at %p\n",
+ switcher_vma->addr);
+ return 0;
+
+free_vma:
+ vunmap(switcher_vma->addr);
+free_pages:
+ i = TOTAL_SWITCHER_PAGES;
+free_some_pages:
+ for (--i; i >= 0; i--)
+ __free_pages(switcher_page[i], 0);
+ kfree(switcher_page);
+out:
+ return err;
+}
+
+static void unmap_switcher(void)
+{
+ unsigned int i;
+
+ vunmap(switcher_vma->addr);
+ for (i = 0; i < TOTAL_SWITCHER_PAGES; i++)
+ __free_pages(switcher_page[i], 0);
+}
+
+/* IN/OUT insns: enough to get us past boot-time probing. */
+static int emulate_insn(struct lguest *lg)
+{
+ u8 insn;
+ unsigned int insnlen = 0, in = 0, shift = 0;
+ unsigned long physaddr = guest_pa(lg, lg->regs->eip);
+
+ /* This only works for addresses in linear mapping... */
+ if (lg->regs->eip < lg->page_offset)
+ return 0;
+ lgread(lg, &insn, physaddr, 1);
+
+ /* Operand size prefix means it's actually for ax. */
+ if (insn == 0x66) {
+ shift = 16;
+ insnlen = 1;
+ lgread(lg, &insn, physaddr + insnlen, 1);
+ }
+
+ switch (insn & 0xFE) {
+ case 0xE4: /* in <next byte>,%al */
+ insnlen += 2;
+ in = 1;
+ break;
+ case 0xEC: /* in (%dx),%al */
+ insnlen += 1;
+ in = 1;
+ break;
+ case 0xE6: /* out %al,<next byte> */
+ insnlen += 2;
+ break;
+ case 0xEE: /* out %al,(%dx) */
+ insnlen += 1;
+ break;
+ default:
+ return 0;
+ }
+
+ if (in) {
+ /* Lower bit tells is whether it's a 16 or 32 bit access */
+ if (insn & 0x1)
+ lg->regs->eax = 0xFFFFFFFF;
+ else
+ lg->regs->eax |= (0xFFFF << shift);
+ }
+ lg->regs->eip += insnlen;
+ return 1;
+}
+
+int lguest_address_ok(const struct lguest *lg,
+ unsigned long addr, unsigned long len)
+{
+ return (addr+len) / PAGE_SIZE < lg->pfn_limit && (addr+len >= addr);
+}
+
+/* Just like get_user, but don't let guest access lguest binary. */
+u32 lgread_u32(struct lguest *lg, u32 addr)
+{
+ u32 val = 0;
+
+ /* Don't let them access lguest binary */
+ if (!lguest_address_ok(lg, addr, sizeof(val))
+ || get_user(val, (u32 __user *)addr) != 0)
+ kill_guest(lg, "bad read address %u", addr);
+ return val;
+}
+
+void lgwrite_u32(struct lguest *lg, u32 addr, u32 val)
+{
+ if (!lguest_address_ok(lg, addr, sizeof(val))
+ || put_user(val, (u32 __user *)addr) != 0)
+ kill_guest(lg, "bad write address %u", addr);
+}
+
+void lgread(struct lguest *lg, void *b, u32 addr, unsigned bytes)
+{
+ if (!lguest_address_ok(lg, addr, bytes)
+ || copy_from_user(b, (void __user *)addr, bytes) != 0) {
+ /* copy_from_user should do this, but as we rely on it... */
+ memset(b, 0, bytes);
+ kill_guest(lg, "bad read address %u len %u", addr, bytes);
+ }
+}
+
+void lgwrite(struct lguest *lg, u32 addr, const void *b, unsigned bytes)
+{
+ if (!lguest_address_ok(lg, addr, bytes)
+ || copy_to_user((void __user *)addr, b, bytes) != 0)
+ kill_guest(lg, "bad write address %u len %u", addr, bytes);
+}
+
+static void set_ts(void)
+{
+ u32 cr0;
+
+ cr0 = read_cr0();
+ if (!(cr0 & 8))
+ write_cr0(cr0|8);
+}
+
+static void copy_in_guest_info(struct lguest *lg, struct lguest_pages *pages)
+{
+ if (__get_cpu_var(last_guest) != lg || lg->last_pages != pages) {
+ __get_cpu_var(last_guest) = lg;
+ lg->last_pages = pages;
+ lg->changed = CHANGED_ALL;
+ }
+
+ /* These are pretty cheap, so we do them unconditionally. */
+ pages->state.host_cr3 = __pa(current->mm->pgd);
+ map_switcher_in_guest(lg, pages);
+ pages->state.guest_tss.esp1 = lg->esp1;
+ pages->state.guest_tss.ss1 = lg->ss1;
+
+ /* Copy direct trap entries. */
+ if (lg->changed & CHANGED_IDT)
+ copy_traps(lg, pages->state.guest_idt, default_idt_entries);
+
+ /* Copy all GDT entries but the TSS. */
+ if (lg->changed & CHANGED_GDT)
+ copy_gdt(lg, pages->state.guest_gdt);
+
+ lg->changed = 0;
+}
+
+static void run_guest_once(struct lguest *lg, struct lguest_pages *pages)
+{
+ unsigned int clobber;
+
+ copy_in_guest_info(lg, pages);
+
+ /* Put eflags on stack, lcall does rest: suitable for iret return. */
+ asm volatile("pushf; lcall *lguest_entry"
+ : "=a"(clobber), "=b"(clobber)
+ : "0"(pages), "1"(__pa(lg->pgdirs[lg->pgdidx].pgdir))
+ : "memory", "%edx", "%ecx", "%edi", "%esi");
+}
+
+int run_guest(struct lguest *lg, char *__user user)
+{
+ while (!lg->dead) {
+ unsigned int cr2 = 0; /* Damn gcc */
+
+ /* Hypercalls first: we might have been out to userspace */
+ do_hypercalls(lg);
+ if (lg->dma_is_pending) {
+ put_user(lg->pending_dma, (unsigned long *)user);
+ put_user(lg->pending_key, (unsigned long *)user+1);
+ return sizeof(unsigned long)*2;
+ }
+
+ if (signal_pending(current))
+ return -EINTR;
+ maybe_do_interrupt(lg);
+
+ try_to_freeze();
+
+ if (lg->dead)
+ break;
+
+ if (lg->halted) {
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule_timeout(1);
+ continue;
+ }
+
+ local_irq_disable();
+
+ /* Even if *we* don't want FPU trap, guest might... */
+ if (lg->ts)
+ set_ts();
+
+ run_guest_once(lg, lguest_pages(raw_smp_processor_id()));
+
+ /* Save cr2 now if we page-faulted. */
+ if (lg->regs->trapnum == 14)
+ cr2 = read_cr2();
+ else if (lg->regs->trapnum == 7)
+ math_state_restore();
+ local_irq_enable();
+
+ switch (lg->regs->trapnum) {
+ case 13: /* We've intercepted a GPF. */
+ if (lg->regs->errcode == 0) {
+ if (emulate_insn(lg))
+ continue;
+ }
+ break;
+ case 14: /* We've intercepted a page fault. */
+ if (demand_page(lg, cr2, lg->regs->errcode & 2))
+ continue;
+
+ /* If lguest_data is NULL, this won't hurt. */
+ put_user(cr2, &lg->lguest_data->cr2);
+ break;
+ case 7: /* We've intercepted a Device Not Available fault. */
+ /* If they don't want to know, just absorb it. */
+ if (!lg->ts)
+ continue;
+ break;
+ case 32 ... 255: /* Real interrupt, fall thru */
+ cond_resched();
+ case LGUEST_TRAP_ENTRY: /* Handled at top of loop */
+ continue;
+ }
+
+ if (deliver_trap(lg, lg->regs->trapnum))
+ continue;
+
+ kill_guest(lg, "unhandled trap %i at %#x (%#x)",
+ lg->regs->trapnum, lg->regs->eip,
+ lg->regs->trapnum == 14 ? cr2 : lg->regs->errcode);
+ }
+ return -ENOENT;
+}
+
+int find_free_guest(void)
+{
+ unsigned int i;
+ for (i = 0; i < MAX_LGUEST_GUESTS; i++)
+ if (!lguests[i].tsk)
+ return i;
+ return -1;
+}
+
+static void adjust_pge(void *on)
+{
+ if (on)
+ write_cr4(read_cr4() | X86_CR4_PGE);
+ else
+ write_cr4(read_cr4() & ~X86_CR4_PGE);
+}
+
+static int __init init(void)
+{
+ int err;
+
+ if (paravirt_enabled()) {
+ printk("lguest is afraid of %s\n", paravirt_ops.name);
+ return -EPERM;
+ }
+
+ err = map_switcher();
+ if (err)
+ return err;
+
+ err = init_pagetables(switcher_page, SHARED_SWITCHER_PAGES);
+ if (err) {
+ unmap_switcher();
+ return err;
+ }
+ lguest_io_init();
+
+ err = lguest_device_init();
+ if (err) {
+ free_pagetables();
+ unmap_switcher();
+ return err;
+ }
+ lock_cpu_hotplug();
+ if (cpu_has_pge) { /* We have a broader idea of "global". */
+ cpu_had_pge = 1;
+ on_each_cpu(adjust_pge, 0, 0, 1);
+ clear_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
+ }
+ unlock_cpu_hotplug();
+ return 0;
+}
+
+static void __exit fini(void)
+{
+ lguest_device_remove();
+ free_pagetables();
+ unmap_switcher();
+ lock_cpu_hotplug();
+ if (cpu_had_pge) {
+ set_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
+ on_each_cpu(adjust_pge, (void *)1, 0, 1);
+ }
+ unlock_cpu_hotplug();
+}
+
+module_init(init);
+module_exit(fini);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
===================================================================
--- /dev/null
+++ b/drivers/lguest/hypercalls.c
@@ -0,0 +1,172 @@
+/* Actual hypercalls, which allow guests to actually do something.
+ Copyright (C) 2006 Rusty Russell IBM Corporation
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+*/
+#include <linux/uaccess.h>
+#include <linux/syscalls.h>
+#include <linux/mm.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <irq_vectors.h>
+#include "lg.h"
+
+static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
+{
+ switch (regs->eax) {
+ case LHCALL_FLUSH_ASYNC:
+ break;
+ case LHCALL_LGUEST_INIT:
+ kill_guest(lg, "already have lguest_data");
+ break;
+ case LHCALL_CRASH: {
+ char msg[128];
+ lgread(lg, msg, regs->edx, sizeof(msg));
+ msg[sizeof(msg)-1] = '\0';
+ kill_guest(lg, "CRASH: %s", msg);
+ break;
+ }
+ case LHCALL_FLUSH_TLB:
+ if (regs->edx)
+ guest_pagetable_clear_all(lg);
+ else
+ guest_pagetable_flush_user(lg);
+ break;
+ case LHCALL_TIMER_READ: {
+ u32 now = jiffies;
+ mb();
+ regs->eax = now - lg->last_timer;
+ lg->last_timer = now;
+ break;
+ }
+ case LHCALL_GET_WALLCLOCK: {
+ struct timespec ts;
+ ktime_get_real_ts(&ts);
+ regs->eax = ts.tv_sec;
+ break;
+ }
+ case LHCALL_BIND_DMA:
+ regs->eax = bind_dma(lg, regs->edx, regs->ebx,
+ regs->ecx >> 8, regs->ecx & 0xFF);
+ break;
+ case LHCALL_SEND_DMA:
+ send_dma(lg, regs->edx, regs->ebx);
+ break;
+ case LHCALL_LOAD_GDT:
+ load_guest_gdt(lg, regs->edx, regs->ebx);
+ break;
+ case LHCALL_LOAD_IDT_ENTRY:
+ load_guest_idt_entry(lg, regs->edx, regs->ebx, regs->ecx);
+ break;
+ case LHCALL_NEW_PGTABLE:
+ guest_new_pagetable(lg, regs->edx);
+ break;
+ case LHCALL_SET_STACK:
+ guest_set_stack(lg, regs->edx, regs->ebx, regs->ecx);
+ break;
+ case LHCALL_SET_PTE:
+ guest_set_pte(lg, regs->edx, regs->ebx, mkgpte(regs->ecx));
+ break;
+ case LHCALL_SET_PMD:
+ guest_set_pmd(lg, regs->edx, regs->ebx);
+ break;
+ case LHCALL_LOAD_TLS:
+ guest_load_tls(lg, (struct desc_struct __user*)regs->edx);
+ break;
+ case LHCALL_TS:
+ lg->ts = regs->edx;
+ break;
+ case LHCALL_HALT:
+ lg->halted = 1;
+ break;
+ default:
+ kill_guest(lg, "Bad hypercall %i\n", regs->eax);
+ }
+}
+
+/* We always do queued calls before actual hypercall. */
+static void do_async_hcalls(struct lguest *lg)
+{
+ unsigned int i;
+ u8 st[LHCALL_RING_SIZE];
+
+ copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st));
+ for (i = 0; i < ARRAY_SIZE(st); i++) {
+ struct lguest_regs regs;
+ unsigned int n = lg->next_hcall;
+
+ if (st[n] == 0xFF)
+ break;
+
+ if (++lg->next_hcall == LHCALL_RING_SIZE)
+ lg->next_hcall = 0;
+
+ get_user(regs.eax, &lg->lguest_data->hcalls[n].eax);
+ get_user(regs.edx, &lg->lguest_data->hcalls[n].edx);
+ get_user(regs.ecx, &lg->lguest_data->hcalls[n].ecx);
+ get_user(regs.ebx, &lg->lguest_data->hcalls[n].ebx);
+ do_hcall(lg, &regs);
+ put_user(0xFF, &lg->lguest_data->hcall_status[n]);
+ if (lg->dma_is_pending)
+ break;
+ }
+}
+
+static void initialize(struct lguest *lg)
+{
+ if (lg->regs->eax != LHCALL_LGUEST_INIT) {
+ kill_guest(lg, "hypercall %i before LGUEST_INIT",
+ lg->regs->eax);
+ return;
+ }
+
+ lg->lguest_data = (struct lguest_data __user *)lg->regs->edx;
+ /* We check here so we can simply copy_to_user/from_user */
+ if (!lguest_address_ok(lg, (long)lg->lguest_data,
+ sizeof(*lg->lguest_data))) {
+ kill_guest(lg, "bad guest page %p", lg->lguest_data);
+ return;
+ }
+ get_user(lg->noirq_start, &lg->lguest_data->noirq_start);
+ get_user(lg->noirq_end, &lg->lguest_data->noirq_end);
+ /* We reserve the top pgd entry. */
+ put_user(4U*1024*1024, &lg->lguest_data->reserve_mem);
+ put_user(lg->guestid, &lg->lguest_data->guestid);
+}
+
+/* Even if we go out to userspace and come back, we don't want to do
+ * the hypercall again. */
+static void clear_hcall(struct lguest *lg)
+{
+ lg->regs->trapnum = 255;
+}
+
+void do_hypercalls(struct lguest *lg)
+{
+ if (unlikely(!lg->lguest_data)) {
+ if (lg->regs->trapnum == LGUEST_TRAP_ENTRY) {
+ initialize(lg);
+ clear_hcall(lg);
+ }
+ return;
+ }
+
+ do_async_hcalls(lg);
+ if (!lg->dma_is_pending && lg->regs->trapnum == LGUEST_TRAP_ENTRY) {
+ do_hcall(lg, lg->regs);
+ clear_hcall(lg);
+ }
+ set_wakeup_process(lg, NULL);
+}
===================================================================
--- /dev/null
+++ b/drivers/lguest/interrupts_and_traps.c
@@ -0,0 +1,258 @@
+#include <linux/uaccess.h>
+#include "lg.h"
+
+static unsigned long idt_address(u32 lo, u32 hi)
+{
+ return (lo & 0x0000FFFF) | (hi & 0xFFFF0000);
+}
+
+static int idt_type(u32 lo, u32 hi)
+{
+ return (hi >> 8) & 0xF;
+}
+
+static int idt_present(u32 lo, u32 hi)
+{
+ return (hi & 0x8000);
+}
+
+static void push_guest_stack(struct lguest *lg, u32 __user **gstack, u32 val)
+{
+ lgwrite_u32(lg, (u32)--(*gstack), val);
+}
+
+static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err)
+{
+ u32 __user *gstack;
+ u32 eflags, ss, irq_enable;
+
+ /* If they want a ring change, we use new stack and push old ss/esp */
+ if ((lg->regs->ss&0x3) != GUEST_PL) {
+ gstack = (u32 __user *)guest_pa(lg, lg->esp1);
+ ss = lg->ss1;
+ push_guest_stack(lg, &gstack, lg->regs->ss);
+ push_guest_stack(lg, &gstack, lg->regs->esp);
+ } else {
+ gstack = (u32 __user *)guest_pa(lg, lg->regs->esp);
+ ss = lg->regs->ss;
+ }
+
+ /* We use IF bit in eflags to indicate whether irqs were disabled
+ (it's always 0, since irqs are enabled when guest is running). */
+ eflags = lg->regs->eflags;
+ get_user(irq_enable, &lg->lguest_data->irq_enabled);
+ eflags |= (irq_enable & X86_EFLAGS_IF);
+
+ push_guest_stack(lg, &gstack, eflags);
+ push_guest_stack(lg, &gstack, lg->regs->cs);
+ push_guest_stack(lg, &gstack, lg->regs->eip);
+
+ if (has_err)
+ push_guest_stack(lg, &gstack, lg->regs->errcode);
+
+ /* Change the real stack so switcher returns to trap handler */
+ lg->regs->ss = ss;
+ lg->regs->esp = (u32)gstack + lg->page_offset;
+ lg->regs->cs = (__KERNEL_CS|GUEST_PL);
+ lg->regs->eip = idt_address(lo, hi);
+
+ /* Disable interrupts for an interrupt gate. */
+ if (idt_type(lo, hi) == 0xE)
+ put_user(0, &lg->lguest_data->irq_enabled);
+}
+
+void maybe_do_interrupt(struct lguest *lg)
+{
+ unsigned int irq;
+ DECLARE_BITMAP(blk, LGUEST_IRQS);
+ struct desc_struct *idt;
+
+ if (!lg->lguest_data)
+ return;
+
+ /* If timer has changed, set timer interrupt. */
+ if (jiffies != lg->last_timer)
+ set_bit(0, lg->irqs_pending);
+
+ /* Mask out any interrupts they have blocked. */
+ copy_from_user(&blk, lg->lguest_data->blocked_interrupts, sizeof(blk));
+ bitmap_andnot(blk, lg->irqs_pending, blk, LGUEST_IRQS);
+
+ irq = find_first_bit(blk, LGUEST_IRQS);
+ if (irq >= LGUEST_IRQS)
+ return;
+
+ if (lg->regs->eip >= lg->noirq_start && lg->regs->eip < lg->noirq_end)
+ return;
+
+ /* If they're halted, we re-enable interrupts. */
+ if (lg->halted) {
+ /* Re-enable interrupts. */
+ put_user(X86_EFLAGS_IF, &lg->lguest_data->irq_enabled);
+ lg->halted = 0;
+ } else {
+ /* Maybe they have interrupts disabled? */
+ u32 irq_enabled;
+ get_user(irq_enabled, &lg->lguest_data->irq_enabled);
+ if (!irq_enabled)
+ return;
+ }
+
+ idt = &lg->idt[FIRST_EXTERNAL_VECTOR+irq];
+ if (idt_present(idt->a, idt->b)) {
+ clear_bit(irq, lg->irqs_pending);
+ set_guest_interrupt(lg, idt->a, idt->b, 0);
+ }
+}
+
+static int has_err(unsigned int trap)
+{
+ return (trap == 8 || (trap >= 10 && trap <= 14) || trap == 17);
+}
+
+int deliver_trap(struct lguest *lg, unsigned int num)
+{
+ u32 lo = lg->idt[num].a, hi = lg->idt[num].b;
+
+ if (!idt_present(lo, hi))
+ return 0;
+ set_guest_interrupt(lg, lo, hi, has_err(num));
+ return 1;
+}
+
+static int direct_trap(const struct lguest *lg,
+ const struct desc_struct *trap,
+ unsigned int num)
+{
+ /* Hardware interrupts don't go to guest (except syscall). */
+ if (num >= FIRST_EXTERNAL_VECTOR && num != SYSCALL_VECTOR)
+ return 0;
+
+ /* We intercept page fault (demand shadow paging & cr2 saving)
+ protection fault (in/out emulation) and device not
+ available (TS handling), and hypercall */
+ if (num == 14 || num == 13 || num == 7 || num == LGUEST_TRAP_ENTRY)
+ return 0;
+
+ /* Interrupt gates (0xE) or not present (0x0) can't go direct. */
+ return idt_type(trap->a, trap->b) == 0xF;
+}
+
+static void pin_stack_pages(struct lguest *lg)
+{
+ unsigned int i;
+
+ for (i = 0; i < lg->stack_pages; i++)
+ pin_page(lg, lg->esp1 - i * PAGE_SIZE);
+}
+
+/* We need to ensure all the direct trap pages are mapped after we
+ * clear shadow mappings. */
+void pin_trap_pages(struct lguest *lg)
+{
+ unsigned int i;
+ struct desc_struct *trap;
+
+ for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++) {
+ trap = &lg->idt[i];
+ if (direct_trap(lg, trap, i))
+ pin_page(lg, idt_address(trap->a, trap->b));
+ }
+
+ trap = &lg->syscall_idt;
+ if (direct_trap(lg, trap, SYSCALL_VECTOR))
+ pin_page(lg, idt_address(trap->a, trap->b));
+ pin_stack_pages(lg);
+}
+
+void guest_set_stack(struct lguest *lg, u32 seg, u32 esp, unsigned int pages)
+{
+ /* You cannot have a stack segment with priv level 0. */
+ if ((seg & 0x3) != GUEST_PL)
+ kill_guest(lg, "bad stack segment %i", seg);
+ if (pages > 2)
+ kill_guest(lg, "bad stack pages %u", pages);
+ lg->ss1 = seg;
+ lg->esp1 = esp;
+ lg->stack_pages = pages;
+ pin_stack_pages(lg);
+}
+
+/* Set up trap in IDT. */
+static void set_trap(struct lguest *lg, struct desc_struct *trap,
+ unsigned int num, u32 lo, u32 hi)
+{
+ u8 type = idt_type(lo, hi);
+
+ if (!idt_present(lo, hi)) {
+ trap->a = trap->b = 0;
+ return;
+ }
+
+ if (type != 0xE && type != 0xF)
+ kill_guest(lg, "bad IDT type %i", type);
+
+ trap->a = ((__KERNEL_CS|GUEST_PL)<<16) | (lo&0x0000FFFF);
+ trap->b = (hi&0xFFFFEF00);
+
+ /* Make sure trap address is available so we don't fault. In
+ * theory, it could overlap two pages, in practice it's aligned. */
+ if (direct_trap(lg, trap, num))
+ pin_page(lg, idt_address(lo, hi));
+}
+
+void load_guest_idt_entry(struct lguest *lg, unsigned int num, u32 lo, u32 hi)
+{
+ /* Guest never handles: NMI, doublefault, hypercall, spurious irq. */
+ if (num == 2 || num == 8 || num == 15 || num == LGUEST_TRAP_ENTRY)
+ return;
+
+ lg->changed |= CHANGED_IDT;
+ if (num < ARRAY_SIZE(lg->idt))
+ set_trap(lg, &lg->idt[num], num, lo, hi);
+ else if (num == SYSCALL_VECTOR)
+ set_trap(lg, &lg->syscall_idt, num, lo, hi);
+}
+
+static void default_idt_entry(struct desc_struct *idt,
+ int trap,
+ const unsigned long handler)
+{
+ u32 flags = 0x8e00;
+
+ /* They can't "int" into any of them except hypercall. */
+ if (trap == LGUEST_TRAP_ENTRY)
+ flags |= (GUEST_PL << 13);
+
+ idt->a = (LGUEST_CS<<16) | (handler&0x0000FFFF);
+ idt->b = (handler&0xFFFF0000) | flags;
+}
+
+void setup_default_idt_entries(struct lguest_ro_state *state,
+ const unsigned long *def)
+{
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(state->guest_idt); i++)
+ default_idt_entry(&state->guest_idt[i], i, def[i]);
+}
+
+void copy_traps(const struct lguest *lg, struct desc_struct *idt,
+ const unsigned long *def)
+{
+ unsigned int i;
+
+ /* All hardware interrupts are same whatever the guest: only the
+ * traps might be different. */
+ for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++) {
+ if (direct_trap(lg, &lg->idt[i], i))
+ idt[i] = lg->idt[i];
+ else
+ default_idt_entry(&idt[i], i, def[i]);
+ }
+ i = SYSCALL_VECTOR;
+ if (direct_trap(lg, &lg->syscall_idt, i))
+ idt[i] = lg->syscall_idt;
+ else
+ default_idt_entry(&idt[i], i, def[i]);
+}
===================================================================
--- /dev/null
+++ b/drivers/lguest/io.c
@@ -0,0 +1,412 @@
+/* Simple I/O model for guests, based on shared memory.
+ * Copyright (C) 2006 Rusty Russell IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#include <linux/types.h>
+#include <linux/futex.h>
+#include <linux/jhash.h>
+#include <linux/mm.h>
+#include <linux/highmem.h>
+#include <linux/uaccess.h>
+#include "lg.h"
+
+static struct list_head dma_hash[61];
+
+void lguest_io_init(void)
+{
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(dma_hash); i++)
+ INIT_LIST_HEAD(&dma_hash[i]);
+}
+
+/* FIXME: allow multi-page lengths. */
+static int check_dma_list(struct lguest *lg, const struct lguest_dma *dma)
+{
+ unsigned int i;
+
+ for (i = 0; i < LGUEST_MAX_DMA_SECTIONS; i++) {
+ if (!dma->len[i])
+ return 1;
+ if (!lguest_address_ok(lg, dma->addr[i], dma->len[i]))
+ goto kill;
+ if (dma->len[i] > PAGE_SIZE)
+ goto kill;
+ /* We could do over a page, but is it worth it? */
+ if ((dma->addr[i] % PAGE_SIZE) + dma->len[i] > PAGE_SIZE)
+ goto kill;
+ }
+ return 1;
+
+kill:
+ kill_guest(lg, "bad DMA entry: %u@%#x", dma->len[i], dma->addr[i]);
+ return 0;
+}
+
+static unsigned int hash(const union futex_key *key)
+{
+ return jhash2((u32*)&key->both.word,
+ (sizeof(key->both.word)+sizeof(key->both.ptr))/4,
+ key->both.offset)
+ % ARRAY_SIZE(dma_hash);
+}
+
+static inline int key_eq(const union futex_key *a, const union futex_key *b)
+{
+ return (a->both.word == b->both.word
+ && a->both.ptr == b->both.ptr
+ && a->both.offset == b->both.offset);
+}
+
+/* Must hold read lock on dmainfo owner's current->mm->mmap_sem */
+static void unlink_dma(struct lguest_dma_info *dmainfo)
+{
+ BUG_ON(!mutex_is_locked(&lguest_lock));
+ dmainfo->interrupt = 0;
+ list_del(&dmainfo->list);
+ drop_futex_key_refs(&dmainfo->key);
+}
+
+static int unbind_dma(struct lguest *lg,
+ const union futex_key *key,
+ unsigned long dmas)
+{
+ int i, ret = 0;
+
+ for (i = 0; i < LGUEST_MAX_DMA; i++) {
+ if (key_eq(key, &lg->dma[i].key) && dmas == lg->dma[i].dmas) {
+ unlink_dma(&lg->dma[i]);
+ ret = 1;
+ break;
+ }
+ }
+ return ret;
+}
+
+int bind_dma(struct lguest *lg,
+ unsigned long ukey, unsigned long dmas, u16 numdmas, u8 interrupt)
+{
+ unsigned int i;
+ int ret = 0;
+ union futex_key key;
+
+ if (interrupt >= LGUEST_IRQS)
+ return 0;
+
+ mutex_lock(&lguest_lock);
+ down_read(&current->mm->mmap_sem);
+ if (get_futex_key((u32 __user *)ukey, &key) != 0) {
+ kill_guest(lg, "bad dma key %#lx", ukey);
+ goto unlock;
+ }
+ get_futex_key_refs(&key);
+
+ if (interrupt == 0)
+ ret = unbind_dma(lg, &key, dmas);
+ else {
+ for (i = 0; i < LGUEST_MAX_DMA; i++) {
+ if (lg->dma[i].interrupt)
+ continue;
+
+ lg->dma[i].dmas = dmas;
+ lg->dma[i].num_dmas = numdmas;
+ lg->dma[i].next_dma = 0;
+ lg->dma[i].key = key;
+ lg->dma[i].guestid = lg->guestid;
+ lg->dma[i].interrupt = interrupt;
+ list_add(&lg->dma[i].list, &dma_hash[hash(&key)]);
+ ret = 1;
+ goto unlock;
+ }
+ }
+ drop_futex_key_refs(&key);
+unlock:
+ up_read(&current->mm->mmap_sem);
+ mutex_unlock(&lguest_lock);
+ return ret;
+}
+
+/* lgread from another guest */
+static int lgread_other(struct lguest *lg,
+ void *buf, u32 addr, unsigned bytes)
+{
+ if (!lguest_address_ok(lg, addr, bytes)
+ || access_process_vm(lg->tsk, addr, buf, bytes, 0) != bytes) {
+ memset(buf, 0, bytes);
+ kill_guest(lg, "bad address in registered DMA struct");
+ return 0;
+ }
+ return 1;
+}
+
+/* lgwrite to another guest */
+static int lgwrite_other(struct lguest *lg, u32 addr,
+ const void *buf, unsigned bytes)
+{
+ if (!lguest_address_ok(lg, addr, bytes)
+ || (access_process_vm(lg->tsk, addr, (void *)buf, bytes, 1)
+ != bytes)) {
+ kill_guest(lg, "bad address writing to registered DMA");
+ return 0;
+ }
+ return 1;
+}
+
+static u32 copy_data(struct lguest *srclg,
+ const struct lguest_dma *src,
+ const struct lguest_dma *dst,
+ struct page *pages[])
+{
+ unsigned int totlen, si, di, srcoff, dstoff;
+ void *maddr = NULL;
+
+ totlen = 0;
+ si = di = 0;
+ srcoff = dstoff = 0;
+ while (si < LGUEST_MAX_DMA_SECTIONS && src->len[si]
+ && di < LGUEST_MAX_DMA_SECTIONS && dst->len[di]) {
+ u32 len = min(src->len[si] - srcoff, dst->len[di] - dstoff);
+
+ if (!maddr)
+ maddr = kmap(pages[di]);
+
+ /* FIXME: This is not completely portable, since
+ archs do different things for copy_to_user_page. */
+ if (copy_from_user(maddr + (dst->addr[di] + dstoff)%PAGE_SIZE,
+ (void *__user)src->addr[si], len) != 0) {
+ kill_guest(srclg, "bad address in sending DMA");
+ totlen = 0;
+ break;
+ }
+
+ totlen += len;
+ srcoff += len;
+ dstoff += len;
+ if (srcoff == src->len[si]) {
+ si++;
+ srcoff = 0;
+ }
+ if (dstoff == dst->len[di]) {
+ kunmap(pages[di]);
+ maddr = NULL;
+ di++;
+ dstoff = 0;
+ }
+ }
+
+ if (maddr)
+ kunmap(pages[di]);
+
+ return totlen;
+}
+
+/* Src is us, ie. current. */
+static u32 do_dma(struct lguest *srclg, const struct lguest_dma *src,
+ struct lguest *dstlg, const struct lguest_dma *dst)
+{
+ int i;
+ u32 ret;
+ struct page *pages[LGUEST_MAX_DMA_SECTIONS];
+
+ if (!check_dma_list(dstlg, dst) || !check_dma_list(srclg, src))
+ return 0;
+
+ /* First get the destination pages */
+ for (i = 0; i < LGUEST_MAX_DMA_SECTIONS; i++) {
+ if (dst->len[i] == 0)
+ break;
+ if (get_user_pages(dstlg->tsk, dstlg->mm,
+ dst->addr[i], 1, 1, 1, pages+i, NULL)
+ != 1) {
+ kill_guest(dstlg, "Error mapping DMA pages");
+ ret = 0;
+ goto drop_pages;
+ }
+ }
+
+ /* Now copy until we run out of src or dst. */
+ ret = copy_data(srclg, src, dst, pages);
+
+drop_pages:
+ while (--i >= 0)
+ put_page(pages[i]);
+ return ret;
+}
+
+static int dma_transfer(struct lguest *srclg,
+ unsigned long udma,
+ struct lguest_dma_info *dst)
+{
+ struct lguest_dma dst_dma, src_dma;
+ struct lguest *dstlg;
+ u32 i, dma = 0;
+
+ dstlg = &lguests[dst->guestid];
+ /* Get our dma list. */
+ lgread(srclg, &src_dma, udma, sizeof(src_dma));
+
+ /* We can't deadlock against them dmaing to us, because this
+ * is all under the lguest_lock. */
+ down_read(&dstlg->mm->mmap_sem);
+
+ for (i = 0; i < dst->num_dmas; i++) {
+ dma = (dst->next_dma + i) % dst->num_dmas;
+ if (!lgread_other(dstlg, &dst_dma,
+ dst->dmas + dma * sizeof(struct lguest_dma),
+ sizeof(dst_dma))) {
+ goto fail;
+ }
+ if (!dst_dma.used_len)
+ break;
+ }
+ if (i != dst->num_dmas) {
+ unsigned long used_lenp;
+ unsigned int ret;
+
+ ret = do_dma(srclg, &src_dma, dstlg, &dst_dma);
+ /* Put used length in src. */
+ lgwrite_u32(srclg,
+ udma+offsetof(struct lguest_dma, used_len), ret);
+ if (ret == 0 && src_dma.len[0] != 0)
+ goto fail;
+
+ /* Make sure destination sees contents before length. */
+ wmb();
+ used_lenp = dst->dmas
+ + dma * sizeof(struct lguest_dma)
+ + offsetof(struct lguest_dma, used_len);
+ lgwrite_other(dstlg, used_lenp, &ret, sizeof(ret));
+ dst->next_dma++;
+ }
+ up_read(&dstlg->mm->mmap_sem);
+
+ /* Do this last so dst doesn't simply sleep on lock. */
+ set_bit(dst->interrupt, dstlg->irqs_pending);
+ set_wakeup_process(srclg, dstlg->tsk);
+ return i == dst->num_dmas;
+
+fail:
+ up_read(&dstlg->mm->mmap_sem);
+ return 0;
+}
+
+void send_dma(struct lguest *lg, unsigned long ukey, unsigned long udma)
+{
+ union futex_key key;
+ int empty = 0;
+
+again:
+ mutex_lock(&lguest_lock);
+ down_read(&current->mm->mmap_sem);
+ if (get_futex_key((u32 __user *)ukey, &key) != 0) {
+ kill_guest(lg, "bad sending DMA key");
+ goto unlock;
+ }
+ /* Shared mapping? Look for other guests... */
+ if (key.shared.offset & 1) {
+ struct lguest_dma_info *i;
+ list_for_each_entry(i, &dma_hash[hash(&key)], list) {
+ if (i->guestid == lg->guestid)
+ continue;
+ if (!key_eq(&key, &i->key))
+ continue;
+
+ empty += dma_transfer(lg, udma, i);
+ break;
+ }
+ if (empty == 1) {
+ /* Give any recipients one chance to restock. */
+ up_read(&current->mm->mmap_sem);
+ mutex_unlock(&lguest_lock);
+ set_wakeup_process(lg, NULL);
+ empty++;
+ goto again;
+ }
+ } else {
+ /* Private mapping: tell our userspace. */
+ lg->dma_is_pending = 1;
+ lg->pending_dma = udma;
+ lg->pending_key = ukey;
+ }
+unlock:
+ up_read(&current->mm->mmap_sem);
+ mutex_unlock(&lguest_lock);
+}
+
+void release_all_dma(struct lguest *lg)
+{
+ unsigned int i;
+
+ BUG_ON(!mutex_is_locked(&lguest_lock));
+
+ down_read(&lg->mm->mmap_sem);
+ for (i = 0; i < LGUEST_MAX_DMA; i++) {
+ if (lg->dma[i].interrupt)
+ unlink_dma(&lg->dma[i]);
+ }
+ up_read(&lg->mm->mmap_sem);
+}
+
+/* We cache one process to wakeup: helps for batching & wakes outside locks. */
+void set_wakeup_process(struct lguest *lg, struct task_struct *p)
+{
+ if (p == lg->wake)
+ return;
+
+ if (lg->wake) {
+ wake_up_process(lg->wake);
+ put_task_struct(lg->wake);
+ }
+ lg->wake = p;
+ if (lg->wake)
+ get_task_struct(lg->wake);
+}
+
+/* Userspace wants a dma buffer from this guest. */
+unsigned long get_dma_buffer(struct lguest *lg,
+ unsigned long ukey, unsigned long *interrupt)
+{
+ unsigned long ret = 0;
+ union futex_key key;
+ struct lguest_dma_info *i;
+
+ mutex_lock(&lguest_lock);
+ down_read(&current->mm->mmap_sem);
+ if (get_futex_key((u32 __user *)ukey, &key) != 0) {
+ kill_guest(lg, "bad registered DMA buffer");
+ goto unlock;
+ }
+ list_for_each_entry(i, &dma_hash[hash(&key)], list) {
+ if (key_eq(&key, &i->key) && i->guestid == lg->guestid) {
+ unsigned int j;
+ for (j = 0; j < i->num_dmas; j++) {
+ struct lguest_dma dma;
+
+ ret = i->dmas + j * sizeof(struct lguest_dma);
+ lgread(lg, &dma, ret, sizeof(dma));
+ if (dma.used_len == 0)
+ break;
+ }
+ *interrupt = i->interrupt;
+ break;
+ }
+ }
+unlock:
+ up_read(&current->mm->mmap_sem);
+ mutex_unlock(&lguest_lock);
+ return ret;
+}
+
===================================================================
--- /dev/null
+++ b/drivers/lguest/lg.h
@@ -0,0 +1,278 @@
+#ifndef _LGUEST_H
+#define _LGUEST_H
+
+#include <asm/desc.h>
+
+#define GDT_ENTRY_LGUEST_CS 10
+#define GDT_ENTRY_LGUEST_DS 11
+#define LGUEST_CS (GDT_ENTRY_LGUEST_CS * 8)
+#define LGUEST_DS (GDT_ENTRY_LGUEST_DS * 8)
+
+#ifndef __ASSEMBLY__
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/stringify.h>
+#include <linux/binfmts.h>
+#include <linux/futex.h>
+#include <linux/lguest.h>
+#include <linux/lguest_launcher.h>
+#include <linux/err.h>
+#include <asm/semaphore.h>
+#include "irq_vectors.h"
+
+#define GUEST_PL 1
+
+struct lguest_regs
+{
+ /* Manually saved part. */
+ u32 ebx, ecx, edx;
+ u32 esi, edi, ebp;
+ u32 gs;
+ u32 eax;
+ u32 fs, ds, es;
+ u32 trapnum, errcode;
+ /* Trap pushed part */
+ u32 eip;
+ u32 cs;
+ u32 eflags;
+ u32 esp;
+ u32 ss;
+};
+
+void free_pagetables(void);
+int init_pagetables(struct page **switcher_page, unsigned int pages);
+
+/* Full 4G segment descriptors, suitable for CS and DS. */
+#define FULL_EXEC_SEGMENT ((struct desc_struct){0x0000ffff, 0x00cf9b00})
+#define FULL_SEGMENT ((struct desc_struct){0x0000ffff, 0x00cf9300})
+
+struct lguest_dma_info
+{
+ struct list_head list;
+ union futex_key key;
+ unsigned long dmas;
+ u16 next_dma;
+ u16 num_dmas;
+ u16 guestid;
+ u8 interrupt; /* 0 when not registered */
+};
+
+/* We have separate types for the guest's ptes & pgds and the shadow ptes &
+ * pgds. Since this host might use three-level pagetables and the guest and
+ * shadow pagetables don't, we can't use the normal pte_t/pgd_t. */
+typedef union {
+ struct { unsigned flags:12, pfn:20; };
+ struct { unsigned long val; } raw;
+} spgd_t;
+typedef union {
+ struct { unsigned flags:12, pfn:20; };
+ struct { unsigned long val; } raw;
+} spte_t;
+typedef union {
+ struct { unsigned flags:12, pfn:20; };
+ struct { unsigned long val; } raw;
+} gpgd_t;
+typedef union {
+ struct { unsigned flags:12, pfn:20; };
+ struct { unsigned long val; } raw;
+} gpte_t;
+#define mkgpte(_val) ((gpte_t){.raw.val = _val})
+#define mkgpgd(_val) ((gpgd_t){.raw.val = _val})
+
+struct pgdir
+{
+ unsigned long cr3;
+ spgd_t *pgdir;
+};
+
+/* FIXME: When this is defined in processor.h, delete this definition. */
+struct i386_hw_tss {
+ unsigned short back_link,__blh;
+ unsigned long esp0;
+ unsigned short ss0,__ss0h;
+ unsigned long esp1;
+ unsigned short ss1,__ss1h; /* ss1 is used to cache MSR_IA32_SYSENTER_CS */
+ unsigned long esp2;
+ unsigned short ss2,__ss2h;
+ unsigned long __cr3;
+ unsigned long eip;
+ unsigned long eflags;
+ unsigned long eax,ecx,edx,ebx;
+ unsigned long esp;
+ unsigned long ebp;
+ unsigned long esi;
+ unsigned long edi;
+ unsigned short es, __esh;
+ unsigned short cs, __csh;
+ unsigned short ss, __ssh;
+ unsigned short ds, __dsh;
+ unsigned short fs, __fsh;
+ unsigned short gs, __gsh;
+ unsigned short ldt, __ldth;
+ unsigned short trace, io_bitmap_base;
+};
+
+/* This is a guest-specific page (mapped ro) into the guest. */
+struct lguest_ro_state
+{
+ /* Host information we need to restore when we switch back. */
+ u32 host_cr3;
+ struct Xgt_desc_struct host_idt_desc;
+ struct Xgt_desc_struct host_gdt_desc;
+ u32 host_sp;
+
+ /* Fields which are used when guest is running. */
+ struct Xgt_desc_struct guest_idt_desc;
+ struct Xgt_desc_struct guest_gdt_desc;
+ struct i386_hw_tss guest_tss;
+ struct desc_struct guest_idt[IDT_ENTRIES];
+ struct desc_struct guest_gdt[GDT_ENTRIES];
+};
+
+/* We have two pages shared with guests, per cpu. */
+struct lguest_pages
+{
+ /* This is the stack page mapped rw in guest */
+ char spare[PAGE_SIZE - sizeof(struct lguest_regs)];
+ struct lguest_regs regs;
+
+ /* This is the host state & guest descriptor page, ro in guest */
+ struct lguest_ro_state state;
+} __attribute__((aligned(PAGE_SIZE)));
+
+#define CHANGED_IDT 1
+#define CHANGED_GDT 2
+#define CHANGED_ALL 3
+
+/* The private info the thread maintains about the guest. */
+struct lguest
+{
+ /* At end of a page shared mapped over lguest_pages in guest. */
+ unsigned long regs_page;
+ struct lguest_regs *regs;
+ struct lguest_data __user *lguest_data;
+ struct task_struct *tsk;
+ struct mm_struct *mm; /* == tsk->mm, but that becomes NULL on exit */
+ u16 guestid;
+ u32 pfn_limit;
+ u32 page_offset;
+ u32 cr2;
+ int halted;
+ int ts;
+ u32 last_timer;
+ u32 next_hcall;
+ u32 esp1;
+ u8 ss1;
+
+ /* Bitmap of what has changed: see CHANGED_* above. */
+ int changed;
+ struct lguest_pages *last_pages;
+
+ /* We keep a small number of these. */
+ u32 pgdidx;
+ struct pgdir pgdirs[4];
+
+ /* Cached wakeup: we hold a reference to this task. */
+ struct task_struct *wake;
+
+ unsigned long noirq_start, noirq_end;
+ int dma_is_pending;
+ unsigned long pending_dma; /* struct lguest_dma */
+ unsigned long pending_key; /* address they're sending to */
+
+ unsigned int stack_pages;
+
+ struct lguest_dma_info dma[LGUEST_MAX_DMA];
+
+ /* Dead? */
+ const char *dead;
+
+ /* The GDT entries copied into lguest_ro_state when running. */
+ struct desc_struct gdt[GDT_ENTRIES];
+
+ /* The IDT entries: some copied into lguest_ro_state when running. */
+ struct desc_struct idt[FIRST_EXTERNAL_VECTOR+LGUEST_IRQS];
+ struct desc_struct syscall_idt;
+
+ /* Pending virtual interrupts */
+ DECLARE_BITMAP(irqs_pending, LGUEST_IRQS);
+};
+
+extern struct lguest lguests[];
+extern struct mutex lguest_lock;
+
+/* core.c: */
+u32 lgread_u32(struct lguest *lg, u32 addr);
+void lgwrite_u32(struct lguest *lg, u32 val, u32 addr);
+void lgread(struct lguest *lg, void *buf, u32 addr, unsigned bytes);
+void lgwrite(struct lguest *lg, u32 addr, const void *buf, unsigned bytes);
+int find_free_guest(void);
+int lguest_address_ok(const struct lguest *lg,
+ unsigned long addr, unsigned long len);
+int run_guest(struct lguest *lg, char *__user user);
+
+
+/* interrupts_and_traps.c: */
+void maybe_do_interrupt(struct lguest *lg);
+int deliver_trap(struct lguest *lg, unsigned int num);
+void load_guest_idt_entry(struct lguest *lg, unsigned int i, u32 low, u32 hi);
+void guest_set_stack(struct lguest *lg, u32 seg, u32 esp, unsigned int pages);
+void pin_trap_pages(struct lguest *lg);
+void setup_default_idt_entries(struct lguest_ro_state *state,
+ const unsigned long *def);
+void copy_traps(const struct lguest *lg, struct desc_struct *idt,
+ const unsigned long *def);
+
+/* segments.c: */
+void setup_default_gdt_entries(struct lguest_ro_state *state);
+void setup_guest_gdt(struct lguest *lg);
+void load_guest_gdt(struct lguest *lg, u32 table, u32 num);
+void guest_load_tls(struct lguest *lg,
+ const struct desc_struct __user *tls_array);
+void copy_gdt(const struct lguest *lg, struct desc_struct *gdt);
+
+/* page_tables.c: */
+int init_guest_pagetable(struct lguest *lg, unsigned long pgtable);
+void free_guest_pagetable(struct lguest *lg);
+void guest_new_pagetable(struct lguest *lg, unsigned long pgtable);
+void guest_set_pmd(struct lguest *lg, unsigned long cr3, u32 i);
+void guest_pagetable_clear_all(struct lguest *lg);
+void guest_pagetable_flush_user(struct lguest *lg);
+void guest_set_pte(struct lguest *lg, unsigned long cr3,
+ unsigned long vaddr, gpte_t val);
+void map_switcher_in_guest(struct lguest *lg, struct lguest_pages *pages);
+int demand_page(struct lguest *info, unsigned long cr2, int write);
+void pin_page(struct lguest *lg, unsigned long vaddr);
+
+/* lguest_user.c: */
+int lguest_device_init(void);
+void lguest_device_remove(void);
+
+/* io.c: */
+void lguest_io_init(void);
+int bind_dma(struct lguest *lg,
+ unsigned long key, unsigned long udma, u16 numdmas, u8 interrupt);
+void send_dma(struct lguest *info, unsigned long key, unsigned long udma);
+void release_all_dma(struct lguest *lg);
+unsigned long get_dma_buffer(struct lguest *lg, unsigned long key,
+ unsigned long *interrupt);
+void set_wakeup_process(struct lguest *lg, struct task_struct *p);
+
+/* hypercalls.c: */
+void do_hypercalls(struct lguest *lg);
+
+#define kill_guest(lg, fmt...) \
+do { \
+ if (!(lg)->dead) { \
+ (lg)->dead = kasprintf(GFP_ATOMIC, fmt); \
+ if (!(lg)->dead) \
+ (lg)->dead = ERR_PTR(-ENOMEM); \
+ } \
+} while(0)
+
+static inline unsigned long guest_pa(struct lguest *lg, unsigned long vaddr)
+{
+ return vaddr - lg->page_offset;
+}
+#endif /* __ASSEMBLY__ */
+#endif /* _LGUEST_H */
===================================================================
--- /dev/null
+++ b/drivers/lguest/lguest_user.c
@@ -0,0 +1,192 @@
+/* Userspace control of the guest, via /dev/lguest. */
+#include <linux/uaccess.h>
+#include <linux/miscdevice.h>
+#include <linux/fs.h>
+#include "lg.h"
+
+static void setup_regs(struct lguest_regs *regs, unsigned long start)
+{
+ /* Write out stack in format lguest expects, so we can switch to it. */
+ regs->edi = LGUEST_MAGIC_EDI;
+ regs->ebp = LGUEST_MAGIC_EBP;
+ regs->esi = LGUEST_MAGIC_ESI;
+ regs->ds = regs->es = regs->ss = __KERNEL_DS|GUEST_PL;
+ regs->cs = __KERNEL_CS|GUEST_PL;
+ regs->eflags = 0x202; /* Interrupts enabled. */
+ regs->eip = start;
+}
+
+/* + addr */
+static long user_get_dma(struct lguest *lg, const u32 __user *input)
+{
+ unsigned long key, udma, irq;
+
+ if (get_user(key, input) != 0)
+ return -EFAULT;
+ udma = get_dma_buffer(lg, key, &irq);
+ if (!udma)
+ return -ENOENT;
+
+ /* We put irq number in udma->used_len. */
+ lgwrite_u32(lg, udma + offsetof(struct lguest_dma, used_len), irq);
+ return udma;
+}
+
+/* + irq */
+static int user_send_irq(struct lguest *lg, const u32 __user *input)
+{
+ u32 irq;
+
+ if (get_user(irq, input) != 0)
+ return -EFAULT;
+ if (irq >= LGUEST_IRQS)
+ return -EINVAL;
+ set_bit(irq, lg->irqs_pending);
+ return 0;
+}
+
+static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
+{
+ struct lguest *lg = file->private_data;
+
+ if (!lg)
+ return -EINVAL;
+
+ if (lg->dead) {
+ size_t len;
+
+ if (IS_ERR(lg->dead))
+ return PTR_ERR(lg->dead);
+
+ len = min(size, strlen(lg->dead)+1);
+ if (copy_to_user(user, lg->dead, len) != 0)
+ return -EFAULT;
+ return len;
+ }
+
+ if (lg->dma_is_pending)
+ lg->dma_is_pending = 0;
+
+ return run_guest(lg, user);
+}
+
+/* Take: pfnlimit, pgdir, start, pageoffset. */
+static int initialize(struct file *file, const u32 __user *input)
+{
+ struct lguest *lg;
+ int err, i;
+ u32 args[4];
+
+ if (file->private_data)
+ return -EBUSY;
+
+ if (copy_from_user(args, input, sizeof(args)) != 0)
+ return -EFAULT;
+
+ mutex_lock(&lguest_lock);
+ i = find_free_guest();
+ if (i < 0) {
+ err = -ENOSPC;
+ goto unlock;
+ }
+ lg = &lguests[i];
+ lg->guestid = i;
+ lg->pfn_limit = args[0];
+ lg->page_offset = args[3];
+ lg->regs_page = get_zeroed_page(GFP_KERNEL);
+ if (!lg->regs_page) {
+ err = -ENOMEM;
+ goto release_guest;
+ }
+ lg->regs = (void *)lg->regs_page + PAGE_SIZE - sizeof(*lg->regs);
+
+ err = init_guest_pagetable(lg, args[1]);
+ if (err)
+ goto free_regs;
+
+ setup_regs(lg->regs, args[2]);
+ setup_guest_gdt(lg);
+ lg->tsk = current;
+ lg->mm = get_task_mm(current);
+ lg->last_pages = NULL;
+ mutex_unlock(&lguest_lock);
+
+ file->private_data = lg;
+ return sizeof(args);
+
+free_regs:
+ free_page(lg->regs_page);
+release_guest:
+ memset(lg, 0, sizeof(*lg));
+unlock:
+ mutex_unlock(&lguest_lock);
+ return err;
+}
+
+static ssize_t write(struct file *file, const char __user *input,
+ size_t size, loff_t *off)
+{
+ struct lguest *lg = file->private_data;
+ u32 req;
+
+ if (get_user(req, input) != 0)
+ return -EFAULT;
+ input += sizeof(req);
+
+ if (req != LHREQ_INITIALIZE && !lg)
+ return -EINVAL;
+ if (lg && lg->dead)
+ return -ENOENT;
+
+ switch (req) {
+ case LHREQ_INITIALIZE:
+ return initialize(file, (const u32 __user *)input);
+ case LHREQ_GETDMA:
+ return user_get_dma(lg, (const u32 __user *)input);
+ case LHREQ_IRQ:
+ return user_send_irq(lg, (const u32 __user *)input);
+ default:
+ return -EINVAL;
+ }
+}
+
+static int close(struct inode *inode, struct file *file)
+{
+ struct lguest *lg = file->private_data;
+
+ if (!lg)
+ return 0;
+
+ mutex_lock(&lguest_lock);
+ release_all_dma(lg);
+ free_guest_pagetable(lg);
+ mmput(lg->mm);
+ if (!IS_ERR(lg->dead))
+ kfree(lg->dead);
+ free_page(lg->regs_page);
+ memset(lg, 0, sizeof(*lg));
+ mutex_unlock(&lguest_lock);
+ return 0;
+}
+
+static struct file_operations lguest_fops = {
+ .owner = THIS_MODULE,
+ .release = close,
+ .write = write,
+ .read = read,
+};
+static struct miscdevice lguest_dev = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .name = "lguest",
+ .fops = &lguest_fops,
+};
+
+int __init lguest_device_init(void)
+{
+ return misc_register(&lguest_dev);
+}
+
+void __exit lguest_device_remove(void)
+{
+ misc_deregister(&lguest_dev);
+}
===================================================================
--- /dev/null
+++ b/drivers/lguest/page_tables.c
@@ -0,0 +1,407 @@
+/* Shadow page table operations.
+ * Copyright (C) Rusty Russell IBM Corporation 2006.
+ * GPL v2 and any later version */
+#include <linux/mm.h>
+#include <linux/types.h>
+#include <linux/spinlock.h>
+#include <linux/random.h>
+#include <linux/percpu.h>
+#include <asm/tlbflush.h>
+#include "lg.h"
+
+#define PTES_PER_PAGE_SHIFT 10
+#define PTES_PER_PAGE (1 << PTES_PER_PAGE_SHIFT)
+#define SWITCHER_PGD_INDEX (PTES_PER_PAGE - 1)
+
+static DEFINE_PER_CPU(spte_t *, switcher_pte_pages) = { NULL };
+#define switcher_pte_page(cpu) per_cpu(switcher_pte_pages, cpu)
+
+static unsigned vaddr_to_pgd_index(unsigned long vaddr)
+{
+ return vaddr >> (PAGE_SHIFT + PTES_PER_PAGE_SHIFT);
+}
+
+/* These access the shadow versions (ie. the ones used by the CPU). */
+static spgd_t *spgd_addr(struct lguest *lg, u32 i, unsigned long vaddr)
+{
+ unsigned int index = vaddr_to_pgd_index(vaddr);
+
+ if (index >= SWITCHER_PGD_INDEX) {
+ kill_guest(lg, "attempt to access switcher pages");
+ index = 0;
+ }
+ return &lg->pgdirs[i].pgdir[index];
+}
+
+static spte_t *spte_addr(struct lguest *lg, spgd_t spgd, unsigned long vaddr)
+{
+ spte_t *page = __va(spgd.pfn << PAGE_SHIFT);
+ BUG_ON(!(spgd.flags & _PAGE_PRESENT));
+ return &page[(vaddr >> PAGE_SHIFT) % PTES_PER_PAGE];
+}
+
+/* These access the guest versions. */
+static unsigned long gpgd_addr(struct lguest *lg, unsigned long vaddr)
+{
+ unsigned int index = vaddr >> (PAGE_SHIFT + PTES_PER_PAGE_SHIFT);
+ return lg->pgdirs[lg->pgdidx].cr3 + index * sizeof(gpgd_t);
+}
+
+static unsigned long gpte_addr(struct lguest *lg,
+ gpgd_t gpgd, unsigned long vaddr)
+{
+ unsigned long gpage = gpgd.pfn << PAGE_SHIFT;
+ BUG_ON(!(gpgd.flags & _PAGE_PRESENT));
+ return gpage + ((vaddr>>PAGE_SHIFT) % PTES_PER_PAGE) * sizeof(gpte_t);
+}
+
+/* Do a virtual -> physical mapping on a user page. */
+static unsigned long get_pfn(unsigned long virtpfn, int write)
+{
+ struct page *page;
+ unsigned long ret = -1UL;
+
+ down_read(&current->mm->mmap_sem);
+ if (get_user_pages(current, current->mm, virtpfn << PAGE_SHIFT,
+ 1, write, 1, &page, NULL) == 1)
+ ret = page_to_pfn(page);
+ up_read(&current->mm->mmap_sem);
+ return ret;
+}
+
+static spte_t gpte_to_spte(struct lguest *lg, gpte_t gpte, int write)
+{
+ spte_t spte;
+ unsigned long pfn;
+
+ /* We ignore the global flag. */
+ spte.flags = (gpte.flags & ~_PAGE_GLOBAL);
+ pfn = get_pfn(gpte.pfn, write);
+ if (pfn == -1UL) {
+ kill_guest(lg, "failed to get page %u", gpte.pfn);
+ /* Must not put_page() bogus page on cleanup. */
+ spte.flags = 0;
+ }
+ spte.pfn = pfn;
+ return spte;
+}
+
+static void release_pte(spte_t pte)
+{
+ if (pte.flags & _PAGE_PRESENT)
+ put_page(pfn_to_page(pte.pfn));
+}
+
+static void check_gpte(struct lguest *lg, gpte_t gpte)
+{
+ if ((gpte.flags & (_PAGE_PWT|_PAGE_PSE)) || gpte.pfn >= lg->pfn_limit)
+ kill_guest(lg, "bad page table entry");
+}
+
+static void check_gpgd(struct lguest *lg, gpgd_t gpgd)
+{
+ if ((gpgd.flags & ~_PAGE_TABLE) || gpgd.pfn >= lg->pfn_limit)
+ kill_guest(lg, "bad page directory entry");
+}
+
+/* FIXME: We hold reference to pages, which prevents them from being
+ swapped. It'd be nice to have a callback when Linux wants to swap out. */
+
+/* We fault pages in, which allows us to update accessed/dirty bits.
+ * Return true if we got page. */
+int demand_page(struct lguest *lg, unsigned long vaddr, int write)
+{
+ gpgd_t gpgd;
+ spgd_t *spgd;
+ unsigned long gpte_ptr;
+ gpte_t gpte;
+ spte_t *spte;
+
+ gpgd = mkgpgd(lgread_u32(lg, gpgd_addr(lg, vaddr)));
+ if (!(gpgd.flags & _PAGE_PRESENT))
+ return 0;
+
+ spgd = spgd_addr(lg, lg->pgdidx, vaddr);
+ if (!(spgd->flags & _PAGE_PRESENT)) {
+ /* Get a page of PTEs for them. */
+ unsigned long ptepage = get_zeroed_page(GFP_KERNEL);
+ /* FIXME: Steal from self in this case? */
+ if (!ptepage) {
+ kill_guest(lg, "out of memory allocating pte page");
+ return 0;
+ }
+ check_gpgd(lg, gpgd);
+ spgd->raw.val = (__pa(ptepage) | gpgd.flags);
+ }
+
+ gpte_ptr = gpte_addr(lg, gpgd, vaddr);
+ gpte = mkgpte(lgread_u32(lg, gpte_ptr));
+
+ /* No page? */
+ if (!(gpte.flags & _PAGE_PRESENT))
+ return 0;
+
+ /* Write to read-only page? */
+ if (write && !(gpte.flags & _PAGE_RW))
+ return 0;
+
+ check_gpte(lg, gpte);
+ gpte.flags |= _PAGE_ACCESSED;
+ if (write)
+ gpte.flags |= _PAGE_DIRTY;
+
+ /* We're done with the old pte. */
+ spte = spte_addr(lg, *spgd, vaddr);
+ release_pte(*spte);
+
+ /* We don't make it writable if this isn't a write: later
+ * write will fault so we can set dirty bit in guest. */
+ if (gpte.flags & _PAGE_DIRTY)
+ *spte = gpte_to_spte(lg, gpte, 1);
+ else {
+ gpte_t ro_gpte = gpte;
+ ro_gpte.flags &= ~_PAGE_RW;
+ *spte = gpte_to_spte(lg, ro_gpte, 0);
+ }
+
+ /* Now we update dirty/accessed on guest. */
+ lgwrite_u32(lg, gpte_ptr, gpte.raw.val);
+ return 1;
+}
+
+/* This is much faster than the full demand_page logic. */
+static int page_writable(struct lguest *lg, unsigned long vaddr)
+{
+ spgd_t *spgd;
+ unsigned long flags;
+
+ spgd = spgd_addr(lg, lg->pgdidx, vaddr);
+ if (!(spgd->flags & _PAGE_PRESENT))
+ return 0;
+
+ flags = spte_addr(lg, *spgd, vaddr)->flags;
+ return (flags & (_PAGE_PRESENT|_PAGE_RW)) == (_PAGE_PRESENT|_PAGE_RW);
+}
+
+void pin_page(struct lguest *lg, unsigned long vaddr)
+{
+ if (!page_writable(lg, vaddr) && !demand_page(lg, vaddr, 0))
+ kill_guest(lg, "bad trap page %#lx", vaddr);
+}
+
+static void release_pgd(struct lguest *lg, spgd_t *spgd)
+{
+ if (spgd->flags & _PAGE_PRESENT) {
+ unsigned int i;
+ spte_t *ptepage = __va(spgd->pfn << PAGE_SHIFT);
+ for (i = 0; i < PTES_PER_PAGE; i++)
+ release_pte(ptepage[i]);
+ free_page((long)ptepage);
+ spgd->raw.val = 0;
+ }
+}
+
+static void flush_user_mappings(struct lguest *lg, int idx)
+{
+ unsigned int i;
+ for (i = 0; i < vaddr_to_pgd_index(lg->page_offset); i++)
+ release_pgd(lg, lg->pgdirs[idx].pgdir + i);
+}
+
+void guest_pagetable_flush_user(struct lguest *lg)
+{
+ flush_user_mappings(lg, lg->pgdidx);
+}
+
+static unsigned int find_pgdir(struct lguest *lg, unsigned long pgtable)
+{
+ unsigned int i;
+ for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
+ if (lg->pgdirs[i].cr3 == pgtable)
+ break;
+ return i;
+}
+
+static unsigned int new_pgdir(struct lguest *lg,
+ unsigned long cr3,
+ int *blank_pgdir)
+{
+ unsigned int next;
+
+ next = random32() % ARRAY_SIZE(lg->pgdirs);
+ if (!lg->pgdirs[next].pgdir) {
+ lg->pgdirs[next].pgdir = (spgd_t *)get_zeroed_page(GFP_KERNEL);
+ if (!lg->pgdirs[next].pgdir)
+ next = lg->pgdidx;
+ else
+ /* There are no mappings: you'll need to re-pin */
+ *blank_pgdir = 1;
+ }
+ lg->pgdirs[next].cr3 = cr3;
+ /* Release all the non-kernel mappings. */
+ flush_user_mappings(lg, next);
+
+ return next;
+}
+
+void guest_new_pagetable(struct lguest *lg, unsigned long pgtable)
+{
+ int newpgdir, repin = 0;
+
+ newpgdir = find_pgdir(lg, pgtable);
+ if (newpgdir == ARRAY_SIZE(lg->pgdirs))
+ newpgdir = new_pgdir(lg, pgtable, &repin);
+ lg->pgdidx = newpgdir;
+ if (repin)
+ pin_trap_pages(lg);
+}
+
+static void release_all_pagetables(struct lguest *lg)
+{
+ unsigned int i, j;
+
+ for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
+ if (lg->pgdirs[i].pgdir)
+ for (j = 0; j < SWITCHER_PGD_INDEX; j++)
+ release_pgd(lg, lg->pgdirs[i].pgdir + j);
+}
+
+void guest_pagetable_clear_all(struct lguest *lg)
+{
+ release_all_pagetables(lg);
+ pin_trap_pages(lg);
+}
+
+static void do_set_pte(struct lguest *lg, int idx,
+ unsigned long vaddr, gpte_t gpte)
+{
+ spgd_t *spgd = spgd_addr(lg, idx, vaddr);
+ if (spgd->flags & _PAGE_PRESENT) {
+ spte_t *spte = spte_addr(lg, *spgd, vaddr);
+ release_pte(*spte);
+ if (gpte.flags & (_PAGE_DIRTY | _PAGE_ACCESSED)) {
+ check_gpte(lg, gpte);
+ *spte = gpte_to_spte(lg, gpte, gpte.flags&_PAGE_DIRTY);
+ } else
+ spte->raw.val = 0;
+ }
+}
+
+void guest_set_pte(struct lguest *lg,
+ unsigned long cr3, unsigned long vaddr, gpte_t gpte)
+{
+ /* Kernel mappings must be changed on all top levels. */
+ if (vaddr >= lg->page_offset) {
+ unsigned int i;
+ for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
+ if (lg->pgdirs[i].pgdir)
+ do_set_pte(lg, i, vaddr, gpte);
+ } else {
+ int pgdir = find_pgdir(lg, cr3);
+ if (pgdir != ARRAY_SIZE(lg->pgdirs))
+ do_set_pte(lg, pgdir, vaddr, gpte);
+ }
+}
+
+void guest_set_pmd(struct lguest *lg, unsigned long cr3, u32 idx)
+{
+ int pgdir;
+
+ if (idx >= SWITCHER_PGD_INDEX)
+ return;
+
+ pgdir = find_pgdir(lg, cr3);
+ if (pgdir < ARRAY_SIZE(lg->pgdirs))
+ release_pgd(lg, lg->pgdirs[pgdir].pgdir + idx);
+}
+
+int init_guest_pagetable(struct lguest *lg, unsigned long pgtable)
+{
+ /* We assume this in flush_user_mappings, so check now */
+ if (vaddr_to_pgd_index(lg->page_offset) >= SWITCHER_PGD_INDEX)
+ return -EINVAL;
+ lg->pgdidx = 0;
+ lg->pgdirs[lg->pgdidx].cr3 = pgtable;
+ lg->pgdirs[lg->pgdidx].pgdir = (spgd_t*)get_zeroed_page(GFP_KERNEL);
+ if (!lg->pgdirs[lg->pgdidx].pgdir)
+ return -ENOMEM;
+ return 0;
+}
+
+void free_guest_pagetable(struct lguest *lg)
+{
+ unsigned int i;
+
+ release_all_pagetables(lg);
+ for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
+ free_page((long)lg->pgdirs[i].pgdir);
+}
+
+/* Caller must be preempt-safe */
+void map_switcher_in_guest(struct lguest *lg, struct lguest_pages *pages)
+{
+ spte_t *switcher_pte_page = __get_cpu_var(switcher_pte_pages);
+ spgd_t switcher_pgd;
+ spte_t regs_pte;
+
+ /* Since switcher less that 4MB, we simply mug top pte page. */
+ switcher_pgd.pfn = __pa(switcher_pte_page) >> PAGE_SHIFT;
+ switcher_pgd.flags = _PAGE_KERNEL;
+ lg->pgdirs[lg->pgdidx].pgdir[SWITCHER_PGD_INDEX] = switcher_pgd;
+
+ /* Map our regs page over stack page. */
+ regs_pte.pfn = __pa(lg->regs_page) >> PAGE_SHIFT;
+ regs_pte.flags = _PAGE_KERNEL;
+ switcher_pte_page[(unsigned long)pages/PAGE_SIZE%PTES_PER_PAGE]
+ = regs_pte;
+}
+
+static void free_switcher_pte_pages(void)
+{
+ unsigned int i;
+
+ for_each_possible_cpu(i)
+ free_page((long)switcher_pte_page(i));
+}
+
+static __init void populate_switcher_pte_page(unsigned int cpu,
+ struct page *switcher_page[],
+ unsigned int pages)
+{
+ unsigned int i;
+ spte_t *pte = switcher_pte_page(cpu);
+
+ for (i = 0; i < pages; i++) {
+ pte[i].pfn = page_to_pfn(switcher_page[i]);
+ pte[i].flags = _PAGE_PRESENT|_PAGE_ACCESSED;
+ }
+
+ /* We only map this CPU's pages, so guest can't see others. */
+ i = pages + cpu*2;
+
+ /* First page (regs) is rw, second (state) is ro. */
+ pte[i].pfn = page_to_pfn(switcher_page[i]);
+ pte[i].flags = _PAGE_PRESENT|_PAGE_ACCESSED|_PAGE_RW;
+ pte[i+1].pfn = page_to_pfn(switcher_page[i+1]);
+ pte[i+1].flags = _PAGE_PRESENT|_PAGE_ACCESSED;
+}
+
+__init int init_pagetables(struct page **switcher_page, unsigned int pages)
+{
+ unsigned int i;
+
+ for_each_possible_cpu(i) {
+ switcher_pte_page(i) = (spte_t *)get_zeroed_page(GFP_KERNEL);
+ if (!switcher_pte_page(i)) {
+ free_switcher_pte_pages();
+ return -ENOMEM;
+ }
+ populate_switcher_pte_page(i, switcher_page, pages);
+ }
+ return 0;
+}
+
+void free_pagetables(void)
+{
+ free_switcher_pte_pages();
+}
===================================================================
--- /dev/null
+++ b/drivers/lguest/segments.c
@@ -0,0 +1,115 @@
+#include "lg.h"
+
+static int desc_ok(const struct desc_struct *gdt)
+{
+ /* MBZ=0, P=1, DT=1 */
+ return ((gdt->b & 0x00209000) == 0x00009000);
+}
+
+static int segment_present(const struct desc_struct *gdt)
+{
+ return gdt->b & 0x8000;
+}
+
+static int ignored_gdt(unsigned int num)
+{
+ return (num == GDT_ENTRY_TSS
+ || num == GDT_ENTRY_LGUEST_CS
+ || num == GDT_ENTRY_LGUEST_DS
+ || num == GDT_ENTRY_DOUBLEFAULT_TSS);
+}
+
+/* We don't allow removal of CS, DS or SS; it doesn't make sense. */
+static void check_segment_use(struct lguest *lg, unsigned int desc)
+{
+ if (lg->regs->gs / 8 == desc)
+ lg->regs->gs = 0;
+ if (lg->regs->fs / 8 == desc)
+ lg->regs->fs = 0;
+ if (lg->regs->es / 8 == desc)
+ lg->regs->es = 0;
+ if (lg->regs->ds / 8 == desc
+ || lg->regs->cs / 8 == desc
+ || lg->regs->ss / 8 == desc)
+ kill_guest(lg, "Removed live GDT entry %u", desc);
+}
+
+static void fixup_gdt_table(struct lguest *lg)
+{
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(lg->gdt); i++) {
+ /* We never copy these ones to real gdt */
+ if (ignored_gdt(i))
+ continue;
+
+ /* We could fault in switch_to_guest if they are using
+ * a removed segment. */
+ if (!segment_present(&lg->gdt[i])) {
+ check_segment_use(lg, i);
+ continue;
+ }
+
+ if (!desc_ok(&lg->gdt[i]))
+ kill_guest(lg, "Bad GDT descriptor %i", i);
+
+ /* DPL 0 presumably means "for use by guest". */
+ if ((lg->gdt[i].b & 0x00006000) == 0)
+ lg->gdt[i].b |= (GUEST_PL << 13);
+
+ /* Set accessed bit, since gdt isn't writable. */
+ lg->gdt[i].b |= 0x00000100;
+ }
+}
+
+void setup_default_gdt_entries(struct lguest_ro_state *state)
+{
+ struct desc_struct *gdt = state->guest_gdt;
+ unsigned long tss = (unsigned long)&state->guest_tss;
+
+ /* Hypervisor segments. */
+ gdt[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
+ gdt[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
+
+ /* This is the one which we *cannot* copy from guest, since tss
+ is depended on this lguest_ro_state, ie. this cpu. */
+ gdt[GDT_ENTRY_TSS].a = 0x00000067 | (tss << 16);
+ gdt[GDT_ENTRY_TSS].b = 0x00008900 | (tss & 0xFF000000)
+ | ((tss >> 16) & 0x000000FF);
+}
+
+void setup_guest_gdt(struct lguest *lg)
+{
+ lg->gdt[GDT_ENTRY_KERNEL_CS] = FULL_EXEC_SEGMENT;
+ lg->gdt[GDT_ENTRY_KERNEL_DS] = FULL_SEGMENT;
+ lg->gdt[GDT_ENTRY_KERNEL_CS].b |= (GUEST_PL << 13);
+ lg->gdt[GDT_ENTRY_KERNEL_DS].b |= (GUEST_PL << 13);
+}
+
+void copy_gdt(const struct lguest *lg, struct desc_struct *gdt)
+{
+ unsigned int i;
+
+ for (i = 0; i < GDT_ENTRIES; i++)
+ if (!ignored_gdt(i))
+ gdt[i] = lg->gdt[i];
+}
+
+void load_guest_gdt(struct lguest *lg, u32 table, u32 num)
+{
+ if (num > ARRAY_SIZE(lg->gdt))
+ kill_guest(lg, "too many gdt entries %i", num);
+
+ lgread(lg, lg->gdt, table, num * sizeof(lg->gdt[0]));
+ fixup_gdt_table(lg);
+ lg->changed |= CHANGED_GDT;
+}
+
+void guest_load_tls(struct lguest *lg, const struct desc_struct __user *gtls)
+{
+ struct desc_struct *tls = &lg->gdt[GDT_ENTRY_TLS_MIN];
+
+ lgread(lg, tls, (u32)gtls, sizeof(*tls)*GDT_ENTRY_TLS_ENTRIES);
+ fixup_gdt_table(lg);
+ lg->changed |= CHANGED_GDT;
+}
===================================================================
--- /dev/null
+++ b/drivers/lguest/switcher.S
@@ -0,0 +1,159 @@
+/* This code sits at 0xFFC00000 to do the low-level guest<->host switch.
+
+ There is are two pages above us for this CPU (struct lguest_pages).
+ The second page (struct lguest_ro_state) becomes read-only after the
+ context switch. The first page (the stack for traps) remains writable,
+ but while we're in here, the guest cannot be running.
+*/
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+#include "lg.h"
+
+.text
+ENTRY(start_switcher_text)
+
+/* %eax points to lguest pages for this CPU. %ebx contains cr3 value.
+ All normal registers can be clobbered! */
+ENTRY(switch_to_guest)
+ /* Save host segments on host stack. */
+ pushl %es
+ pushl %ds
+ pushl %gs
+ pushl %fs
+ /* With CONFIG_FRAME_POINTER, gcc doesn't let us clobber this! */
+ pushl %ebp
+ /* Save host stack. */
+ movl %esp, LGUEST_PAGES_host_sp(%eax)
+ /* Switch to guest stack: if we get NMI we expect to be there. */
+ movl %eax, %edx
+ addl $LGUEST_PAGES_regs, %edx
+ movl %edx, %esp
+ /* Switch to guest's GDT, IDT. */
+ lgdt LGUEST_PAGES_guest_gdt_desc(%eax)
+ lidt LGUEST_PAGES_guest_idt_desc(%eax)
+ /* Switch to guest's TSS while GDT still writable. */
+ movl $(GDT_ENTRY_TSS*8), %edx
+ ltr %dx
+ /* Set host's TSS GDT entry to available (clear byte 5 bit 2). */
+ movl (LGUEST_PAGES_host_gdt_desc+2)(%eax), %edx
+ andb $0xFD, (GDT_ENTRY_TSS*8 + 5)(%edx)
+ /* Switch to guest page tables: lguest_pages->state now read-only. */
+ movl %ebx, %cr3
+ /* Restore guest regs */
+ popl %ebx
+ popl %ecx
+ popl %edx
+ popl %esi
+ popl %edi
+ popl %ebp
+ popl %gs
+ popl %eax
+ popl %fs
+ popl %ds
+ popl %es
+ /* Skip error code and trap number */
+ addl $8, %esp
+ iret
+
+#define SWITCH_TO_HOST \
+ /* Save guest state */ \
+ pushl %es; \
+ pushl %ds; \
+ pushl %fs; \
+ pushl %eax; \
+ pushl %gs; \
+ pushl %ebp; \
+ pushl %edi; \
+ pushl %esi; \
+ pushl %edx; \
+ pushl %ecx; \
+ pushl %ebx; \
+ /* Load lguest ds segment for convenience. */ \
+ movl $(LGUEST_DS), %eax; \
+ movl %eax, %ds; \
+ /* Figure out where we are, based on stack (at top of regs). */ \
+ movl %esp, %eax; \
+ subl $LGUEST_PAGES_regs, %eax; \
+ /* Put trap number in %ebx before we switch cr3 and lose it. */ \
+ movl LGUEST_PAGES_regs_trapnum(%eax), %ebx; \
+ /* Switch to host page tables (host GDT, IDT and stack are in host \
+ mem, so need this first) */ \
+ movl LGUEST_PAGES_host_cr3(%eax), %edx; \
+ movl %edx, %cr3; \
+ /* Set guest's TSS to available (clear byte 5 bit 2). */ \
+ andb $0xFD, (LGUEST_PAGES_guest_gdt+GDT_ENTRY_TSS*8+5)(%eax); \
+ /* Switch to host's GDT & IDT. */ \
+ lgdt LGUEST_PAGES_host_gdt_desc(%eax); \
+ lidt LGUEST_PAGES_host_idt_desc(%eax); \
+ /* Switch to host's stack. */ \
+ movl LGUEST_PAGES_host_sp(%eax), %esp; \
+ /* Switch to host's TSS */ \
+ movl $(GDT_ENTRY_TSS*8), %edx; \
+ ltr %dx; \
+ popl %ebp; \
+ popl %fs; \
+ popl %gs; \
+ popl %ds; \
+ popl %es
+
+/* Return to run_guest_once. */
+return_to_host:
+ SWITCH_TO_HOST
+ iret
+
+deliver_to_host:
+ SWITCH_TO_HOST
+ /* Decode IDT and jump to hosts' irq handler. When that does iret, it
+ * will return to run_guest_once. This is a feature. */
+ movl (LGUEST_PAGES_host_idt_desc+2)(%eax), %edx
+ leal (%edx,%ebx,8), %eax
+ movzwl (%eax),%edx
+ movl 4(%eax), %eax
+ xorw %ax, %ax
+ orl %eax, %edx
+ jmp *%edx
+
+/* Real hardware interrupts are delivered straight to the host. Others
+ cause us to return to run_guest_once so it can decide what to do. Note
+ that some of these are overridden by the guest to deliver directly, and
+ never enter here (see load_guest_idt_entry). */
+.macro IRQ_STUB N TARGET
+ .data; .long 1f; .text; 1:
+ /* Make an error number for most traps, which don't have one. */
+ .if (\N <> 8) && (\N < 10 || \N > 14) && (\N <> 17)
+ pushl $0
+ .endif
+ pushl $\N
+ jmp \TARGET
+ ALIGN
+.endm
+
+.macro IRQ_STUBS FIRST LAST TARGET
+ irq=\FIRST
+ .rept \LAST-\FIRST+1
+ IRQ_STUB irq \TARGET
+ irq=irq+1
+ .endr
+.endm
+
+/* We intercept every interrupt, because we may need to switch back to
+ * host. Unfortunately we can't tell them apart except by entry
+ * point, so we need 256 entry points.
+ */
+.data
+.global default_idt_entries
+default_idt_entries:
+.text
+ IRQ_STUBS 0 1 return_to_host /* First two traps */
+ IRQ_STUB 2 handle_nmi /* NMI */
+ IRQ_STUBS 3 31 return_to_host /* Rest of traps */
+ IRQ_STUBS 32 127 deliver_to_host /* Real interrupts */
+ IRQ_STUB 128 return_to_host /* System call (overridden) */
+ IRQ_STUBS 129 255 deliver_to_host /* Other real interrupts */
+
+/* We ignore NMI and return. */
+handle_nmi:
+ addl $8, %esp
+ iret
+
+ENTRY(end_switcher_text)
===================================================================
--- /dev/null
+++ b/include/linux/lguest_launcher.h
@@ -0,0 +1,80 @@
+#ifndef _ASM_LGUEST_USER
+#define _ASM_LGUEST_USER
+/* Everything the "lguest" userspace program needs to know. */
+/* They can register up to 32 arrays of lguest_dma. */
+#define LGUEST_MAX_DMA 32
+/* At most we can dma 16 lguest_dma in one op. */
+#define LGUEST_MAX_DMA_SECTIONS 16
+
+/* How many devices? Assume each one wants up to two dma arrays per device. */
+#define LGUEST_MAX_DEVICES (LGUEST_MAX_DMA/2)
+
+struct lguest_dma
+{
+ /* 0 if free to be used, filled by hypervisor. */
+ u32 used_len;
+ u32 addr[LGUEST_MAX_DMA_SECTIONS];
+ u16 len[LGUEST_MAX_DMA_SECTIONS];
+};
+
+/* This is found at address 0. */
+struct lguest_boot_info
+{
+ u32 max_pfn;
+ u32 initrd_size;
+ char cmdline[256];
+};
+
+struct lguest_block_page
+{
+ /* 0 is a read, 1 is a write. */
+ int type;
+ u32 sector; /* Offset in device = sector * 512. */
+ u32 bytes; /* Length expected to be read/written in bytes */
+ /* 0 = pending, 1 = done, 2 = done, error */
+ int result;
+ u32 num_sectors; /* Disk length = num_sectors * 512 */
+};
+
+/* There is a shared page of these. */
+struct lguest_net
+{
+ /* Simply the mac address (with multicast bit meaning promisc). */
+ unsigned char mac[6];
+};
+
+/* Where the Host expects the Guest to SEND_DMA console output to. */
+#define LGUEST_CONSOLE_DMA_KEY 0
+
+/* We have a page of these descriptors in the lguest_device page. */
+struct lguest_device_desc {
+ u16 type;
+#define LGUEST_DEVICE_T_CONSOLE 1
+#define LGUEST_DEVICE_T_NET 2
+#define LGUEST_DEVICE_T_BLOCK 3
+
+ u16 features;
+#define LGUEST_NET_F_NOCSUM 0x4000 /* Don't bother checksumming */
+#define LGUEST_DEVICE_F_RANDOMNESS 0x8000 /* IRQ is fairly random */
+
+ u16 status;
+/* 256 and above are device specific. */
+#define LGUEST_DEVICE_S_ACKNOWLEDGE 1 /* We have seen device. */
+#define LGUEST_DEVICE_S_DRIVER 2 /* We have found a driver */
+#define LGUEST_DEVICE_S_DRIVER_OK 4 /* Driver says OK! */
+#define LGUEST_DEVICE_S_REMOVED 8 /* Device has gone away. */
+#define LGUEST_DEVICE_S_REMOVED_ACK 16 /* Driver has been told. */
+#define LGUEST_DEVICE_S_FAILED 128 /* Something actually failed */
+
+ u16 num_pages;
+ u32 pfn;
+};
+
+/* Write command first word is a request. */
+enum lguest_req
+{
+ LHREQ_INITIALIZE, /* + pfnlimit, pgdir, start, pageoffset */
+ LHREQ_GETDMA, /* + addr (returns &lguest_dma, irq in ->used_len) */
+ LHREQ_IRQ, /* + irq */
+};
+#endif /* _ASM_LGUEST_USER */

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