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    Subject[patch 2/9] lguest: the guest code
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    Date
    From: Rusty Russell <rusty@rustcorp.com.au>

    lguest is a simple hypervisor for Linux on Linux. Unlike kvm it doesn't need
    VT/SVM hardware. Unlike Xen it's simply "modprobe and go". Unlike both, it's
    5000 lines and self-contained.

    Performance is ok, but not great (-30% on kernel compile). But given its
    hackability, I expect this to improve, along with the paravirt_ops code which
    it supplies a complete example for. There's also a 64-bit version being
    worked on and other craziness.

    But most of all, lguest is awesome fun! Too much of the kernel is a big ball
    of hair. lguest is simple enough to dive into and hack, plus has some warts
    which scream "fork me!".


    This patch:

    This is the code and headers required to make an i386 kernel an lguest guest.

    Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
    Cc: Andi Kleen <ak@suse.de>
    Cc: Jeremy Fitzhardinge <jeremy@goop.org>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    ---

    drivers/lguest/lguest.c | 497 ++++++++++++++++++++++++++++++++++
    drivers/lguest/lguest_asm.S | 53 +++
    drivers/lguest/lguest_bus.c | 148 ++++++++++
    include/linux/lguest.h | 85 +++++
    include/linux/lguest_bus.h | 33 ++
    5 files changed, 816 insertions(+)

    diff -puN /dev/null drivers/lguest/lguest.c
    --- /dev/null
    +++ a/drivers/lguest/lguest.c
    @@ -0,0 +1,497 @@
    +/*
    + * Lguest specific paravirt-ops implementation
    + *
    + * Copyright (C) 2006, Rusty Russell <rusty@rustcorp.com.au> 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, GOOD TITLE or
    + * NON INFRINGEMENT. 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., 675 Mass Ave, Cambridge, MA 02139, USA.
    + */
    +#include <linux/kernel.h>
    +#include <linux/start_kernel.h>
    +#include <linux/string.h>
    +#include <linux/console.h>
    +#include <linux/screen_info.h>
    +#include <linux/irq.h>
    +#include <linux/interrupt.h>
    +#include <linux/lguest.h>
    +#include <linux/lguest_launcher.h>
    +#include <asm/paravirt.h>
    +#include <asm/param.h>
    +#include <asm/page.h>
    +#include <asm/pgtable.h>
    +#include <asm/desc.h>
    +#include <asm/setup.h>
    +#include <asm/e820.h>
    +#include <asm/mce.h>
    +
    +/* Declarations for definitions in lguest_guest.S */
    +extern char lguest_noirq_start[], lguest_noirq_end[];
    +extern const char lgstart_cli[], lgend_cli[];
    +extern const char lgstart_sti[], lgend_sti[];
    +extern const char lgstart_popf[], lgend_popf[];
    +extern const char lgstart_pushf[], lgend_pushf[];
    +extern const char lgstart_iret[], lgend_iret[];
    +extern void lguest_iret(void);
    +
    +struct lguest_data lguest_data = {
    + .hcall_status = { [0 ... LHCALL_RING_SIZE-1] = 0xFF },
    + .noirq_start = (u32)lguest_noirq_start,
    + .noirq_end = (u32)lguest_noirq_end,
    + .blocked_interrupts = { 1 }, /* Block timer interrupts */
    +};
    +struct lguest_device_desc *lguest_devices;
    +static __initdata const struct lguest_boot_info *boot = __va(0);
    +
    +static enum paravirt_lazy_mode lazy_mode;
    +static void lguest_lazy_mode(enum paravirt_lazy_mode mode)
    +{
    + if (mode == PARAVIRT_LAZY_FLUSH)
    + hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0);
    + else {
    + lazy_mode = mode;
    + if (mode == PARAVIRT_LAZY_NONE)
    + hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0);
    + }
    +}
    +
    +static void lazy_hcall(unsigned long call,
    + unsigned long arg1,
    + unsigned long arg2,
    + unsigned long arg3)
    +{
    + if (lazy_mode == PARAVIRT_LAZY_NONE)
    + hcall(call, arg1, arg2, arg3);
    + else
    + async_hcall(call, arg1, arg2, arg3);
    +}
    +
    +void async_hcall(unsigned long call,
    + unsigned long arg1, unsigned long arg2, unsigned long arg3)
    +{
    + /* Note: This code assumes we're uniprocessor. */
    + static unsigned int next_call;
    + unsigned long flags;
    +
    + local_irq_save(flags);
    + if (lguest_data.hcall_status[next_call] != 0xFF) {
    + /* Table full, so do normal hcall which will flush table. */
    + hcall(call, arg1, arg2, arg3);
    + } else {
    + lguest_data.hcalls[next_call].eax = call;
    + lguest_data.hcalls[next_call].edx = arg1;
    + lguest_data.hcalls[next_call].ebx = arg2;
    + lguest_data.hcalls[next_call].ecx = arg3;
    + /* Make sure host sees arguments before "valid" flag. */
    + wmb();
    + lguest_data.hcall_status[next_call] = 0;
    + if (++next_call == LHCALL_RING_SIZE)
    + next_call = 0;
    + }
    + local_irq_restore(flags);
    +}
    +
    +static unsigned long save_fl(void)
    +{
    + return lguest_data.irq_enabled;
    +}
    +
    +static void restore_fl(unsigned long flags)
    +{
    + /* FIXME: Check if interrupt pending... */
    + lguest_data.irq_enabled = flags;
    +}
    +
    +static void irq_disable(void)
    +{
    + lguest_data.irq_enabled = 0;
    +}
    +
    +static void irq_enable(void)
    +{
    + /* FIXME: Check if interrupt pending... */
    + lguest_data.irq_enabled = X86_EFLAGS_IF;
    +}
    +
    +static void lguest_write_idt_entry(struct desc_struct *dt,
    + int entrynum, u32 low, u32 high)
    +{
    + write_dt_entry(dt, entrynum, low, high);
    + hcall(LHCALL_LOAD_IDT_ENTRY, entrynum, low, high);
    +}
    +
    +static void lguest_load_idt(const struct Xgt_desc_struct *desc)
    +{
    + unsigned int i;
    + struct desc_struct *idt = (void *)desc->address;
    +
    + for (i = 0; i < (desc->size+1)/8; i++)
    + hcall(LHCALL_LOAD_IDT_ENTRY, i, idt[i].a, idt[i].b);
    +}
    +
    +static void lguest_load_gdt(const struct Xgt_desc_struct *desc)
    +{
    + BUG_ON((desc->size+1)/8 != GDT_ENTRIES);
    + hcall(LHCALL_LOAD_GDT, __pa(desc->address), GDT_ENTRIES, 0);
    +}
    +
    +static void lguest_write_gdt_entry(struct desc_struct *dt,
    + int entrynum, u32 low, u32 high)
    +{
    + write_dt_entry(dt, entrynum, low, high);
    + hcall(LHCALL_LOAD_GDT, __pa(dt), GDT_ENTRIES, 0);
    +}
    +
    +static void lguest_load_tls(struct thread_struct *t, unsigned int cpu)
    +{
    + lazy_hcall(LHCALL_LOAD_TLS, __pa(&t->tls_array), cpu, 0);
    +}
    +
    +static void lguest_set_ldt(const void *addr, unsigned entries)
    +{
    +}
    +
    +static void lguest_load_tr_desc(void)
    +{
    +}
    +
    +static void lguest_cpuid(unsigned int *eax, unsigned int *ebx,
    + unsigned int *ecx, unsigned int *edx)
    +{
    + int function = *eax;
    +
    + native_cpuid(eax, ebx, ecx, edx);
    + switch (function) {
    + case 1: /* Basic feature request. */
    + /* We only allow kernel to see SSE3, CMPXCHG16B and SSSE3 */
    + *ecx &= 0x00002201;
    + /* Similarly: SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, FPU. */
    + *edx &= 0x07808101;
    + /* Host wants to know when we flush kernel pages: set PGE. */
    + *edx |= 0x00002000;
    + break;
    + case 0x80000000:
    + /* Futureproof this a little: if they ask how much extended
    + * processor information, limit it to known fields. */
    + if (*eax > 0x80000008)
    + *eax = 0x80000008;
    + break;
    + }
    +}
    +
    +static unsigned long current_cr0, current_cr3;
    +static void lguest_write_cr0(unsigned long val)
    +{
    + hcall(LHCALL_TS, val & 8, 0, 0);
    + current_cr0 = val;
    +}
    +
    +static unsigned long lguest_read_cr0(void)
    +{
    + return current_cr0;
    +}
    +
    +static void lguest_clts(void)
    +{
    + lazy_hcall(LHCALL_TS, 0, 0, 0);
    + current_cr0 &= ~8U;
    +}
    +
    +static unsigned long lguest_read_cr2(void)
    +{
    + return lguest_data.cr2;
    +}
    +
    +static void lguest_write_cr3(unsigned long cr3)
    +{
    + hcall(LHCALL_NEW_PGTABLE, cr3, 0, 0);
    + current_cr3 = cr3;
    +}
    +
    +static unsigned long lguest_read_cr3(void)
    +{
    + return current_cr3;
    +}
    +
    +/* Used to enable/disable PGE, but we don't care. */
    +static unsigned long lguest_read_cr4(void)
    +{
    + return 0;
    +}
    +
    +static void lguest_write_cr4(unsigned long val)
    +{
    +}
    +
    +static void lguest_set_pte_at(struct mm_struct *mm, unsigned long addr,
    + pte_t *ptep, pte_t pteval)
    +{
    + *ptep = pteval;
    + lazy_hcall(LHCALL_SET_PTE, __pa(mm->pgd), addr, pteval.pte_low);
    +}
    +
    +/* We only support two-level pagetables at the moment. */
    +static void lguest_set_pmd(pmd_t *pmdp, pmd_t pmdval)
    +{
    + *pmdp = pmdval;
    + lazy_hcall(LHCALL_SET_PMD, __pa(pmdp)&PAGE_MASK,
    + (__pa(pmdp)&(PAGE_SIZE-1))/4, 0);
    +}
    +
    +/* FIXME: Eliminate all callers of this. */
    +static void lguest_set_pte(pte_t *ptep, pte_t pteval)
    +{
    + *ptep = pteval;
    + /* Don't bother with hypercall before initial setup. */
    + if (current_cr3)
    + hcall(LHCALL_FLUSH_TLB, 1, 0, 0);
    +}
    +
    +static void lguest_flush_tlb_single(unsigned long addr)
    +{
    + /* Simply set it to zero, and it will fault back in. */
    + lazy_hcall(LHCALL_SET_PTE, current_cr3, addr, 0);
    +}
    +
    +static void lguest_flush_tlb_user(void)
    +{
    + lazy_hcall(LHCALL_FLUSH_TLB, 0, 0, 0);
    +}
    +
    +static void lguest_flush_tlb_kernel(void)
    +{
    + lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0);
    +}
    +
    +static void disable_lguest_irq(unsigned int irq)
    +{
    + set_bit(irq, lguest_data.blocked_interrupts);
    +}
    +
    +static void enable_lguest_irq(unsigned int irq)
    +{
    + clear_bit(irq, lguest_data.blocked_interrupts);
    + /* FIXME: If it's pending? */
    +}
    +
    +static struct irq_chip lguest_irq_controller = {
    + .name = "lguest",
    + .mask = disable_lguest_irq,
    + .mask_ack = disable_lguest_irq,
    + .unmask = enable_lguest_irq,
    +};
    +
    +static void __init lguest_init_IRQ(void)
    +{
    + unsigned int i;
    +
    + for (i = 0; i < LGUEST_IRQS; i++) {
    + int vector = FIRST_EXTERNAL_VECTOR + i;
    + if (vector != SYSCALL_VECTOR) {
    + set_intr_gate(vector, interrupt[i]);
    + set_irq_chip_and_handler(i, &lguest_irq_controller,
    + handle_level_irq);
    + }
    + }
    + irq_ctx_init(smp_processor_id());
    +}
    +
    +static unsigned long lguest_get_wallclock(void)
    +{
    + return hcall(LHCALL_GET_WALLCLOCK, 0, 0, 0);
    +}
    +
    +static void lguest_time_irq(unsigned int irq, struct irq_desc *desc)
    +{
    + do_timer(hcall(LHCALL_TIMER_READ, 0, 0, 0));
    + update_process_times(user_mode_vm(get_irq_regs()));
    +}
    +
    +static void lguest_time_init(void)
    +{
    + set_irq_handler(0, lguest_time_irq);
    + hcall(LHCALL_TIMER_READ, 0, 0, 0);
    + enable_lguest_irq(0);
    +}
    +
    +static void lguest_load_esp0(struct tss_struct *tss,
    + struct thread_struct *thread)
    +{
    + lazy_hcall(LHCALL_SET_STACK, __KERNEL_DS|0x1, thread->esp0,
    + THREAD_SIZE/PAGE_SIZE);
    +}
    +
    +static void lguest_set_debugreg(int regno, unsigned long value)
    +{
    + /* FIXME: Implement */
    +}
    +
    +static void lguest_wbinvd(void)
    +{
    +}
    +
    +#ifdef CONFIG_X86_LOCAL_APIC
    +static void lguest_apic_write(unsigned long reg, unsigned long v)
    +{
    +}
    +
    +static unsigned long lguest_apic_read(unsigned long reg)
    +{
    + return 0;
    +}
    +#endif
    +
    +static void lguest_safe_halt(void)
    +{
    + hcall(LHCALL_HALT, 0, 0, 0);
    +}
    +
    +static void lguest_power_off(void)
    +{
    + hcall(LHCALL_CRASH, __pa("Power down"), 0, 0);
    +}
    +
    +static int lguest_panic(struct notifier_block *nb, unsigned long l, void *p)
    +{
    + hcall(LHCALL_CRASH, __pa(p), 0, 0);
    + return NOTIFY_DONE;
    +}
    +
    +static struct notifier_block paniced = {
    + .notifier_call = lguest_panic
    +};
    +
    +static __init char *lguest_memory_setup(void)
    +{
    + /* We do this here because lockcheck barfs if before start_kernel */
    + atomic_notifier_chain_register(&panic_notifier_list, &paniced);
    +
    + e820.nr_map = 0;
    + add_memory_region(0, PFN_PHYS(boot->max_pfn), E820_RAM);
    + return "LGUEST";
    +}
    +
    +static const struct lguest_insns
    +{
    + const char *start, *end;
    +} lguest_insns[] = {
    + [PARAVIRT_PATCH(irq_disable)] = { lgstart_cli, lgend_cli },
    + [PARAVIRT_PATCH(irq_enable)] = { lgstart_sti, lgend_sti },
    + [PARAVIRT_PATCH(restore_fl)] = { lgstart_popf, lgend_popf },
    + [PARAVIRT_PATCH(save_fl)] = { lgstart_pushf, lgend_pushf },
    +};
    +static unsigned lguest_patch(u8 type, u16 clobber, void *insns, unsigned len)
    +{
    + unsigned int insn_len;
    +
    + /* Don't touch it if we don't have a replacement */
    + if (type >= ARRAY_SIZE(lguest_insns) || !lguest_insns[type].start)
    + return paravirt_patch_default(type, clobber, insns, len);
    +
    + insn_len = lguest_insns[type].end - lguest_insns[type].start;
    +
    + /* Similarly if we can't fit replacement. */
    + if (len < insn_len)
    + return paravirt_patch_default(type, clobber, insns, len);
    +
    + memcpy(insns, lguest_insns[type].start, insn_len);
    + return insn_len;
    +}
    +
    +__init void lguest_init(void)
    +{
    + paravirt_ops.name = "lguest";
    + paravirt_ops.paravirt_enabled = 1;
    + paravirt_ops.kernel_rpl = 1;
    +
    + paravirt_ops.save_fl = save_fl;
    + paravirt_ops.restore_fl = restore_fl;
    + paravirt_ops.irq_disable = irq_disable;
    + paravirt_ops.irq_enable = irq_enable;
    + paravirt_ops.load_gdt = lguest_load_gdt;
    + paravirt_ops.memory_setup = lguest_memory_setup;
    + paravirt_ops.cpuid = lguest_cpuid;
    + paravirt_ops.write_cr3 = lguest_write_cr3;
    + paravirt_ops.flush_tlb_user = lguest_flush_tlb_user;
    + paravirt_ops.flush_tlb_single = lguest_flush_tlb_single;
    + paravirt_ops.flush_tlb_kernel = lguest_flush_tlb_kernel;
    + paravirt_ops.set_pte = lguest_set_pte;
    + paravirt_ops.set_pte_at = lguest_set_pte_at;
    + paravirt_ops.set_pmd = lguest_set_pmd;
    +#ifdef CONFIG_X86_LOCAL_APIC
    + paravirt_ops.apic_write = lguest_apic_write;
    + paravirt_ops.apic_write_atomic = lguest_apic_write;
    + paravirt_ops.apic_read = lguest_apic_read;
    +#endif
    + paravirt_ops.load_idt = lguest_load_idt;
    + paravirt_ops.iret = lguest_iret;
    + paravirt_ops.load_esp0 = lguest_load_esp0;
    + paravirt_ops.load_tr_desc = lguest_load_tr_desc;
    + paravirt_ops.set_ldt = lguest_set_ldt;
    + paravirt_ops.load_tls = lguest_load_tls;
    + paravirt_ops.set_debugreg = lguest_set_debugreg;
    + paravirt_ops.clts = lguest_clts;
    + paravirt_ops.read_cr0 = lguest_read_cr0;
    + paravirt_ops.write_cr0 = lguest_write_cr0;
    + paravirt_ops.init_IRQ = lguest_init_IRQ;
    + paravirt_ops.read_cr2 = lguest_read_cr2;
    + paravirt_ops.read_cr3 = lguest_read_cr3;
    + paravirt_ops.read_cr4 = lguest_read_cr4;
    + paravirt_ops.write_cr4 = lguest_write_cr4;
    + paravirt_ops.write_gdt_entry = lguest_write_gdt_entry;
    + paravirt_ops.write_idt_entry = lguest_write_idt_entry;
    + paravirt_ops.patch = lguest_patch;
    + paravirt_ops.safe_halt = lguest_safe_halt;
    + paravirt_ops.get_wallclock = lguest_get_wallclock;
    + paravirt_ops.time_init = lguest_time_init;
    + paravirt_ops.set_lazy_mode = lguest_lazy_mode;
    + paravirt_ops.wbinvd = lguest_wbinvd;
    +
    + hcall(LHCALL_LGUEST_INIT, __pa(&lguest_data), 0, 0);
    + strncpy(boot_command_line, boot->cmdline, COMMAND_LINE_SIZE);
    +
    + /* We use top of mem for initial pagetables. */
    + init_pg_tables_end = __pa(pg0);
    +
    + asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_DS) : "memory");
    +
    + reserve_top_address(lguest_data.reserve_mem);
    +
    + cpu_detect(&new_cpu_data);
    + /* Need this before paging_init. */
    + set_bit(X86_FEATURE_PGE, new_cpu_data.x86_capability);
    + /* Math is always hard! */
    + new_cpu_data.hard_math = 1;
    +
    +#ifdef CONFIG_X86_MCE
    + mce_disabled = 1;
    +#endif
    +
    +#ifdef CONFIG_ACPI
    + acpi_disabled = 1;
    + acpi_ht = 0;
    +#endif
    +
    + add_preferred_console("hvc", 0, NULL);
    +
    + if (boot->initrd_size) {
    + /* We stash this at top of memory. */
    + INITRD_START = boot->max_pfn*PAGE_SIZE - boot->initrd_size;
    + INITRD_SIZE = boot->initrd_size;
    + LOADER_TYPE = 0xFF;
    + }
    +
    + pm_power_off = lguest_power_off;
    + start_kernel();
    +}
    diff -puN /dev/null drivers/lguest/lguest_asm.S
    --- /dev/null
    +++ a/drivers/lguest/lguest_asm.S
    @@ -0,0 +1,53 @@
    +#include <linux/linkage.h>
    +#include <linux/lguest.h>
    +#include <asm/asm-offsets.h>
    +#include <asm/thread_info.h>
    +
    +/* FIXME: Once asm/processor-flags.h goes in, include that */
    +#define X86_EFLAGS_IF 0x00000200
    +
    +/*
    + * This is where we begin: we have a magic signature which the launcher looks
    + * for. The plan is that the Linux boot protocol will be extended with a
    + * "platform type" field which will guide us here from the normal entry point,
    + * but for the moment this suffices.
    + *
    + * We put it in .init.text will be discarded after boot.
    + */
    +.section .init.text, "ax", @progbits
    +.ascii "GenuineLguest"
    + /* Set up initial stack. */
    + movl $(init_thread_union+THREAD_SIZE),%esp
    + jmp lguest_init
    +
    +/* The templates for inline patching. */
    +#define LGUEST_PATCH(name, insns...) \
    + lgstart_##name: insns; lgend_##name:; \
    + .globl lgstart_##name; .globl lgend_##name
    +
    +LGUEST_PATCH(cli, movl $0, lguest_data+LGUEST_DATA_irq_enabled)
    +LGUEST_PATCH(sti, movl $X86_EFLAGS_IF, lguest_data+LGUEST_DATA_irq_enabled)
    +LGUEST_PATCH(popf, movl %eax, lguest_data+LGUEST_DATA_irq_enabled)
    +LGUEST_PATCH(pushf, movl lguest_data+LGUEST_DATA_irq_enabled, %eax)
    +
    +.text
    +/* These demark the EIP range where host should never deliver interrupts. */
    +.global lguest_noirq_start
    +.global lguest_noirq_end
    +
    +/*
    + * We move eflags word to lguest_data.irq_enabled to restore interrupt state.
    + * For page faults, gpfs and virtual interrupts, the hypervisor has saved
    + * eflags manually, otherwise it was delivered directly and so eflags reflects
    + * the real machine IF state, ie. interrupts on. Since the kernel always dies
    + * if it takes such a trap with interrupts disabled anyway, turning interrupts
    + * back on unconditionally here is OK.
    + */
    +ENTRY(lguest_iret)
    + pushl %eax
    + movl 12(%esp), %eax
    +lguest_noirq_start:
    + movl %eax,%ss:lguest_data+LGUEST_DATA_irq_enabled
    + popl %eax
    + iret
    +lguest_noirq_end:
    diff -puN /dev/null drivers/lguest/lguest_bus.c
    --- /dev/null
    +++ a/drivers/lguest/lguest_bus.c
    @@ -0,0 +1,148 @@
    +#include <linux/init.h>
    +#include <linux/bootmem.h>
    +#include <linux/lguest_bus.h>
    +#include <asm/io.h>
    +
    +static ssize_t type_show(struct device *_dev,
    + struct device_attribute *attr, char *buf)
    +{
    + struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
    + return sprintf(buf, "%hu", lguest_devices[dev->index].type);
    +}
    +static ssize_t features_show(struct device *_dev,
    + struct device_attribute *attr, char *buf)
    +{
    + struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
    + return sprintf(buf, "%hx", lguest_devices[dev->index].features);
    +}
    +static ssize_t pfn_show(struct device *_dev,
    + struct device_attribute *attr, char *buf)
    +{
    + struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
    + return sprintf(buf, "%u", lguest_devices[dev->index].pfn);
    +}
    +static ssize_t status_show(struct device *_dev,
    + struct device_attribute *attr, char *buf)
    +{
    + struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
    + return sprintf(buf, "%hx", lguest_devices[dev->index].status);
    +}
    +static ssize_t status_store(struct device *_dev, struct device_attribute *attr,
    + const char *buf, size_t count)
    +{
    + struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
    + if (sscanf(buf, "%hi", &lguest_devices[dev->index].status) != 1)
    + return -EINVAL;
    + return count;
    +}
    +static struct device_attribute lguest_dev_attrs[] = {
    + __ATTR_RO(type),
    + __ATTR_RO(features),
    + __ATTR_RO(pfn),
    + __ATTR(status, 0644, status_show, status_store),
    + __ATTR_NULL
    +};
    +
    +static int lguest_dev_match(struct device *_dev, struct device_driver *_drv)
    +{
    + struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
    + struct lguest_driver *drv = container_of(_drv,struct lguest_driver,drv);
    +
    + return (drv->device_type == lguest_devices[dev->index].type);
    +}
    +
    +struct lguest_bus {
    + struct bus_type bus;
    + struct device dev;
    +};
    +
    +static struct lguest_bus lguest_bus = {
    + .bus = {
    + .name = "lguest",
    + .match = lguest_dev_match,
    + .dev_attrs = lguest_dev_attrs,
    + },
    + .dev = {
    + .parent = NULL,
    + .bus_id = "lguest",
    + }
    +};
    +
    +static int lguest_dev_probe(struct device *_dev)
    +{
    + int ret;
    + struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
    + struct lguest_driver *drv = container_of(dev->dev.driver,
    + struct lguest_driver, drv);
    +
    + lguest_devices[dev->index].status |= LGUEST_DEVICE_S_DRIVER;
    + ret = drv->probe(dev);
    + if (ret == 0)
    + lguest_devices[dev->index].status |= LGUEST_DEVICE_S_DRIVER_OK;
    + return ret;
    +}
    +
    +int register_lguest_driver(struct lguest_driver *drv)
    +{
    + if (!lguest_devices)
    + return 0;
    +
    + drv->drv.bus = &lguest_bus.bus;
    + drv->drv.name = drv->name;
    + drv->drv.owner = drv->owner;
    + drv->drv.probe = lguest_dev_probe;
    +
    + return driver_register(&drv->drv);
    +}
    +EXPORT_SYMBOL_GPL(register_lguest_driver);
    +
    +static void add_lguest_device(unsigned int index)
    +{
    + struct lguest_device *new;
    +
    + lguest_devices[index].status |= LGUEST_DEVICE_S_ACKNOWLEDGE;
    + new = kmalloc(sizeof(struct lguest_device), GFP_KERNEL);
    + if (!new) {
    + printk(KERN_EMERG "Cannot allocate lguest device %u\n", index);
    + lguest_devices[index].status |= LGUEST_DEVICE_S_FAILED;
    + return;
    + }
    +
    + new->index = index;
    + new->private = NULL;
    + memset(&new->dev, 0, sizeof(new->dev));
    + new->dev.parent = &lguest_bus.dev;
    + new->dev.bus = &lguest_bus.bus;
    + sprintf(new->dev.bus_id, "%u", index);
    + if (device_register(&new->dev) != 0) {
    + printk(KERN_EMERG "Cannot register lguest device %u\n", index);
    + lguest_devices[index].status |= LGUEST_DEVICE_S_FAILED;
    + kfree(new);
    + }
    +}
    +
    +static void scan_devices(void)
    +{
    + unsigned int i;
    +
    + for (i = 0; i < LGUEST_MAX_DEVICES; i++)
    + if (lguest_devices[i].type)
    + add_lguest_device(i);
    +}
    +
    +static int __init lguest_bus_init(void)
    +{
    + if (strcmp(paravirt_ops.name, "lguest") != 0)
    + return 0;
    +
    + /* Devices are in page above top of "normal" mem. */
    + lguest_devices = ioremap(max_pfn << PAGE_SHIFT, PAGE_SIZE);
    +
    + if (bus_register(&lguest_bus.bus) != 0
    + || device_register(&lguest_bus.dev) != 0)
    + panic("lguest bus registration failed");
    +
    + scan_devices();
    + return 0;
    +}
    +postcore_initcall(lguest_bus_init);
    diff -puN /dev/null include/linux/lguest.h
    --- /dev/null
    +++ a/include/linux/lguest.h
    @@ -0,0 +1,85 @@
    +/* Things the lguest guest needs to know. Note: like all lguest interfaces,
    + * this is subject to wild and random change between versions. */
    +#ifndef _ASM_LGUEST_H
    +#define _ASM_LGUEST_H
    +
    +/* These are randomly chosen numbers which indicate we're an lguest at boot */
    +#define LGUEST_MAGIC_EBP 0x4C687970
    +#define LGUEST_MAGIC_EDI 0x652D4D65
    +#define LGUEST_MAGIC_ESI 0xFFFFFFFF
    +
    +#ifndef __ASSEMBLY__
    +#include <asm/irq.h>
    +
    +#define LHCALL_FLUSH_ASYNC 0
    +#define LHCALL_LGUEST_INIT 1
    +#define LHCALL_CRASH 2
    +#define LHCALL_LOAD_GDT 3
    +#define LHCALL_NEW_PGTABLE 4
    +#define LHCALL_FLUSH_TLB 5
    +#define LHCALL_LOAD_IDT_ENTRY 6
    +#define LHCALL_SET_STACK 7
    +#define LHCALL_TS 8
    +#define LHCALL_TIMER_READ 9
    +#define LHCALL_HALT 10
    +#define LHCALL_GET_WALLCLOCK 11
    +#define LHCALL_BIND_DMA 12
    +#define LHCALL_SEND_DMA 13
    +#define LHCALL_SET_PTE 14
    +#define LHCALL_SET_PMD 15
    +#define LHCALL_LOAD_TLS 16
    +
    +#define LGUEST_TRAP_ENTRY 0x1F
    +
    +static inline unsigned long
    +hcall(unsigned long call,
    + unsigned long arg1, unsigned long arg2, unsigned long arg3)
    +{
    + asm volatile("int $" __stringify(LGUEST_TRAP_ENTRY)
    + : "=a"(call)
    + : "a"(call), "d"(arg1), "b"(arg2), "c"(arg3)
    + : "memory");
    + return call;
    +}
    +
    +void async_hcall(unsigned long call,
    + unsigned long arg1, unsigned long arg2, unsigned long arg3);
    +
    +/* Can't use our min() macro here: needs to be a constant */
    +#define LGUEST_IRQS (NR_IRQS < 32 ? NR_IRQS: 32)
    +
    +#define LHCALL_RING_SIZE 64
    +struct hcall_ring
    +{
    + u32 eax, edx, ebx, ecx;
    +};
    +
    +/* All the good stuff happens here: guest registers it with LGUEST_INIT */
    +struct lguest_data
    +{
    +/* Fields which change during running: */
    + /* 512 == enabled (same as eflags) */
    + unsigned int irq_enabled;
    + /* Interrupts blocked by guest. */
    + DECLARE_BITMAP(blocked_interrupts, LGUEST_IRQS);
    +
    + /* Virtual address of page fault. */
    + unsigned long cr2;
    +
    + /* Async hypercall ring. 0xFF == done, 0 == pending. */
    + u8 hcall_status[LHCALL_RING_SIZE];
    + struct hcall_ring hcalls[LHCALL_RING_SIZE];
    +
    +/* Fields initialized by the hypervisor at boot: */
    + /* Memory not to try to access */
    + unsigned long reserve_mem;
    + /* ID of this guest (used by network driver to set ethernet address) */
    + u16 guestid;
    +
    +/* Fields initialized by the guest at boot: */
    + /* Instruction range to suppress interrupts even if enabled */
    + unsigned long noirq_start, noirq_end;
    +};
    +extern struct lguest_data lguest_data;
    +#endif /* __ASSEMBLY__ */
    +#endif /* _ASM_LGUEST_H */
    diff -puN /dev/null include/linux/lguest_bus.h
    --- /dev/null
    +++ a/include/linux/lguest_bus.h
    @@ -0,0 +1,33 @@
    +#ifndef _ASM_LGUEST_DEVICE_H
    +#define _ASM_LGUEST_DEVICE_H
    +/* Everything you need to know about lguest devices. */
    +#include <linux/device.h>
    +#include <linux/lguest.h>
    +#include <linux/lguest_launcher.h>
    +
    +struct lguest_device {
    + /* Unique busid, and index into lguest_page->devices[] */
    + /* By convention, each device can use irq index+1 if it wants to. */
    + unsigned int index;
    +
    + struct device dev;
    +
    + /* Driver can hang data off here. */
    + void *private;
    +};
    +
    +struct lguest_driver {
    + const char *name;
    + struct module *owner;
    + u16 device_type;
    + int (*probe)(struct lguest_device *dev);
    + void (*remove)(struct lguest_device *dev);
    +
    + struct device_driver drv;
    +};
    +
    +extern int register_lguest_driver(struct lguest_driver *drv);
    +extern void unregister_lguest_driver(struct lguest_driver *drv);
    +
    +extern struct lguest_device_desc *lguest_devices; /* Just past max_pfn */
    +#endif /* _ASM_LGUEST_DEVICE_H */
    _
    -
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