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Subject[PATCH 9/13] KVM: define exit handlers
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Date
This defines exit handlers for:

- exceptions (only page faults normally)
- control register access
- invlpg
- I/O instructions
- interrupt window management (exit when guest interrupts are enabled)

Signed-off-by: Yaniv Kamay <yaniv@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

Index: linux-2.6/drivers/kvm/kvm_main.c
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm_main.c
+++ linux-2.6/drivers/kvm/kvm_main.c
@@ -1643,6 +1643,210 @@ static void skip_emulated_instruction(st
interruptibility & ~3);
}

+static int emulator_read_std(unsigned long addr,
+ unsigned long *val,
+ unsigned int bytes,
+ struct x86_emulate_ctxt *ctxt)
+{
+ struct kvm_vcpu *vcpu = ctxt->vcpu;
+ void *data = val;
+
+ while (bytes) {
+ gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
+ unsigned offset = addr & (PAGE_SIZE-1);
+ unsigned tocopy = min(bytes, (unsigned)PAGE_SIZE - offset);
+ unsigned long pfn;
+ struct kvm_memory_slot *memslot;
+ void *page;
+
+ if (gpa == UNMAPPED_GVA)
+ return X86EMUL_PROPAGATE_FAULT;
+ pfn = gpa >> PAGE_SHIFT;
+ memslot = gfn_to_memslot(vcpu->kvm, pfn);
+ if (!memslot)
+ return X86EMUL_UNHANDLEABLE;
+ page = kmap_atomic(gfn_to_page(memslot, pfn), KM_USER0);
+
+ memcpy(data, page + offset, tocopy);
+
+ kunmap_atomic(page, KM_USER0);
+
+ bytes -= tocopy;
+ data += tocopy;
+ addr += tocopy;
+ }
+
+ return X86EMUL_CONTINUE;
+}
+
+static int emulator_write_std(unsigned long addr,
+ unsigned long val,
+ unsigned int bytes,
+ struct x86_emulate_ctxt *ctxt)
+{
+ printk(KERN_ERR "emulator_write_std: addr %lx n %d\n",
+ addr, bytes);
+ return X86EMUL_UNHANDLEABLE;
+}
+
+static int emulator_read_emulated(unsigned long addr,
+ unsigned long *val,
+ unsigned int bytes,
+ struct x86_emulate_ctxt *ctxt)
+{
+ struct kvm_vcpu *vcpu = ctxt->vcpu;
+
+ if (vcpu->mmio_read_completed) {
+ memcpy(val, vcpu->mmio_data, bytes);
+ vcpu->mmio_read_completed = 0;
+ return X86EMUL_CONTINUE;
+ } else if (emulator_read_std(addr, val, bytes, ctxt)
+ == X86EMUL_CONTINUE)
+ return X86EMUL_CONTINUE;
+ else {
+ gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
+ if (gpa == UNMAPPED_GVA)
+ return vcpu_printf(vcpu, "not present\n"), X86EMUL_PROPAGATE_FAULT;
+ vcpu->mmio_needed = 1;
+ vcpu->mmio_phys_addr = gpa;
+ vcpu->mmio_size = bytes;
+ vcpu->mmio_is_write = 0;
+
+ return X86EMUL_UNHANDLEABLE;
+ }
+}
+
+static int emulator_write_emulated(unsigned long addr,
+ unsigned long val,
+ unsigned int bytes,
+ struct x86_emulate_ctxt *ctxt)
+{
+ struct kvm_vcpu *vcpu = ctxt->vcpu;
+ gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
+
+ if (gpa == UNMAPPED_GVA)
+ return X86EMUL_PROPAGATE_FAULT;
+
+ vcpu->mmio_needed = 1;
+ vcpu->mmio_phys_addr = gpa;
+ vcpu->mmio_size = bytes;
+ vcpu->mmio_is_write = 1;
+ memcpy(vcpu->mmio_data, &val, bytes);
+
+ return X86EMUL_CONTINUE;
+}
+
+static int emulator_cmpxchg_emulated(unsigned long addr,
+ unsigned long old,
+ unsigned long new,
+ unsigned int bytes,
+ struct x86_emulate_ctxt *ctxt)
+{
+ static int reported;
+
+ if (!reported) {
+ reported = 1;
+ printk(KERN_WARNING "kvm: emulating exchange as write\n");
+ }
+ return emulator_write_emulated(addr, new, bytes, ctxt);
+}
+
+static void report_emulation_failure(struct x86_emulate_ctxt *ctxt)
+{
+ static int reported;
+ u8 opcodes[4];
+ unsigned long rip = vmcs_readl(GUEST_RIP);
+ unsigned long rip_linear = rip + vmcs_readl(GUEST_CS_BASE);
+
+ if (reported)
+ return;
+
+ emulator_read_std(rip_linear, (void *)opcodes, 4, ctxt);
+
+ printk(KERN_ERR "emulation failed but !mmio_needed?"
+ " rip %lx %02x %02x %02x %02x\n",
+ rip, opcodes[0], opcodes[1], opcodes[2], opcodes[3]);
+ reported = 1;
+}
+
+struct x86_emulate_ops emulate_ops = {
+ .read_std = emulator_read_std,
+ .write_std = emulator_write_std,
+ .read_emulated = emulator_read_emulated,
+ .write_emulated = emulator_write_emulated,
+ .cmpxchg_emulated = emulator_cmpxchg_emulated,
+};
+
+enum emulation_result {
+ EMULATE_DONE, /* no further processing */
+ EMULATE_DO_MMIO, /* kvm_run filled with mmio request */
+ EMULATE_FAIL, /* can't emulate this instruction */
+};
+
+static int emulate_instruction(struct kvm_vcpu *vcpu,
+ struct kvm_run *run,
+ unsigned long cr2,
+ u16 error_code)
+{
+ struct x86_emulate_ctxt emulate_ctxt;
+ int r;
+ u32 cs_ar;
+
+ vcpu_load_rsp_rip(vcpu);
+
+ cs_ar = vmcs_read32(GUEST_CS_AR_BYTES);
+
+ emulate_ctxt.vcpu = vcpu;
+ emulate_ctxt.eflags = vmcs_readl(GUEST_RFLAGS);
+ emulate_ctxt.cr2 = cr2;
+ emulate_ctxt.mode = (emulate_ctxt.eflags & X86_EFLAGS_VM)
+ ? X86EMUL_MODE_REAL : (cs_ar & AR_L_MASK)
+ ? X86EMUL_MODE_PROT64 : (cs_ar & AR_DB_MASK)
+ ? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16;
+
+ if (emulate_ctxt.mode == X86EMUL_MODE_PROT64) {
+ emulate_ctxt.cs_base = 0;
+ emulate_ctxt.ds_base = 0;
+ emulate_ctxt.es_base = 0;
+ emulate_ctxt.ss_base = 0;
+ emulate_ctxt.gs_base = 0;
+ emulate_ctxt.fs_base = 0;
+ } else {
+ emulate_ctxt.cs_base = vmcs_readl(GUEST_CS_BASE);
+ emulate_ctxt.ds_base = vmcs_readl(GUEST_DS_BASE);
+ emulate_ctxt.es_base = vmcs_readl(GUEST_ES_BASE);
+ emulate_ctxt.ss_base = vmcs_readl(GUEST_SS_BASE);
+ emulate_ctxt.gs_base = vmcs_readl(GUEST_GS_BASE);
+ emulate_ctxt.fs_base = vmcs_readl(GUEST_FS_BASE);
+ }
+
+ vcpu->mmio_is_write = 0;
+ r = x86_emulate_memop(&emulate_ctxt, &emulate_ops);
+
+ if ((r || vcpu->mmio_is_write) && run) {
+ run->mmio.phys_addr = vcpu->mmio_phys_addr;
+ memcpy(run->mmio.data, vcpu->mmio_data, 8);
+ run->mmio.len = vcpu->mmio_size;
+ run->mmio.is_write = vcpu->mmio_is_write;
+ }
+
+ if (r) {
+ if (!vcpu->mmio_needed) {
+ report_emulation_failure(&emulate_ctxt);
+ return EMULATE_FAIL;
+ }
+ return EMULATE_DO_MMIO;
+ }
+
+ vcpu_put_rsp_rip(vcpu);
+ vmcs_writel(GUEST_RFLAGS, emulate_ctxt.eflags);
+
+ if (vcpu->mmio_is_write)
+ return EMULATE_DO_MMIO;
+
+ return EMULATE_DONE;
+}
+
static u64 mk_cr_64(u64 curr_cr, u32 new_val)
{
return (curr_cr & ~((1ULL << 32) - 1)) | new_val;
@@ -1706,6 +1910,257 @@ void realmode_set_cr(struct kvm_vcpu *vc
}
}

+static int handle_rmode_exception(struct kvm_vcpu *vcpu,
+ int vec, u32 err_code)
+{
+ if (!vcpu->rmode.active)
+ return 0;
+
+ if (vec == GP_VECTOR && err_code == 0)
+ if (emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DONE)
+ return 1;
+ return 0;
+}
+
+static int handle_exception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+{
+ u32 intr_info, error_code;
+ unsigned long cr2, rip;
+ u32 vect_info;
+ enum emulation_result er;
+
+ vect_info = vmcs_read32(IDT_VECTORING_INFO_FIELD);
+ intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
+
+ if ((vect_info & VECTORING_INFO_VALID_MASK) &&
+ !is_page_fault(intr_info)) {
+ printk(KERN_ERR "%s: unexpected, vectoring info 0x%x "
+ "intr info 0x%x\n", __FUNCTION__, vect_info, intr_info);
+ }
+
+ if (is_external_interrupt(vect_info)) {
+ int irq = vect_info & VECTORING_INFO_VECTOR_MASK;
+ set_bit(irq, vcpu->irq_pending);
+ set_bit(irq / BITS_PER_LONG, &vcpu->irq_summary);
+ }
+
+ if ((intr_info & INTR_INFO_INTR_TYPE_MASK) == 0x200) { /* nmi */
+ asm ("int $2");
+ return 1;
+ }
+ error_code = 0;
+ rip = vmcs_readl(GUEST_RIP);
+ if (intr_info & INTR_INFO_DELIEVER_CODE_MASK)
+ error_code = vmcs_read32(VM_EXIT_INTR_ERROR_CODE);
+ if (is_page_fault(intr_info)) {
+ cr2 = vmcs_readl(EXIT_QUALIFICATION);
+
+ spin_lock(&vcpu->kvm->lock);
+ if (!vcpu->mmu.page_fault(vcpu, cr2, error_code)) {
+ spin_unlock(&vcpu->kvm->lock);
+ return 1;
+ }
+
+ er = emulate_instruction(vcpu, kvm_run, cr2, error_code);
+ spin_unlock(&vcpu->kvm->lock);
+
+ switch (er) {
+ case EMULATE_DONE:
+ return 1;
+ case EMULATE_DO_MMIO:
+ ++kvm_stat.mmio_exits;
+ kvm_run->exit_reason = KVM_EXIT_MMIO;
+ return 0;
+ case EMULATE_FAIL:
+ vcpu_printf(vcpu, "%s: emulate fail\n", __FUNCTION__);
+ break;
+ default:
+ BUG();
+ }
+ }
+
+ if (vcpu->rmode.active &&
+ handle_rmode_exception(vcpu, intr_info & INTR_INFO_VECTOR_MASK,
+ error_code))
+ return 1;
+
+ if ((intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK)) == (INTR_TYPE_EXCEPTION | 1)) {
+ kvm_run->exit_reason = KVM_EXIT_DEBUG;
+ return 0;
+ }
+ kvm_run->exit_reason = KVM_EXIT_EXCEPTION;
+ kvm_run->ex.exception = intr_info & INTR_INFO_VECTOR_MASK;
+ kvm_run->ex.error_code = error_code;
+ return 0;
+}
+
+static int handle_external_interrupt(struct kvm_vcpu *vcpu,
+ struct kvm_run *kvm_run)
+{
+ ++kvm_stat.irq_exits;
+ return 1;
+}
+
+
+static int get_io_count(struct kvm_vcpu *vcpu, u64 *count)
+{
+ u64 inst;
+ gva_t rip;
+ int countr_size;
+ int i, n;
+
+ if ((vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_VM)) {
+ countr_size = 2;
+ } else {
+ u32 cs_ar = vmcs_read32(GUEST_CS_AR_BYTES);
+
+ countr_size = (cs_ar & AR_L_MASK) ? 8:
+ (cs_ar & AR_DB_MASK) ? 4: 2;
+ }
+
+ rip = vmcs_readl(GUEST_RIP);
+ if (countr_size != 8)
+ rip += vmcs_readl(GUEST_CS_BASE);
+
+ n = kvm_read_guest(vcpu, rip, sizeof(inst), &inst);
+
+ for (i = 0; i < n; i++) {
+ switch (((u8*)&inst)[i]) {
+ case 0xf0:
+ case 0xf2:
+ case 0xf3:
+ case 0x2e:
+ case 0x36:
+ case 0x3e:
+ case 0x26:
+ case 0x64:
+ case 0x65:
+ case 0x66:
+ break;
+ case 0x67:
+ countr_size = (countr_size == 2) ? 4: (countr_size >> 1);
+ default:
+ goto done;
+ }
+ }
+ return 0;
+done:
+ countr_size *= 8;
+ *count = vcpu->regs[VCPU_REGS_RCX] & (~0ULL >> (64 - countr_size));
+ return 1;
+}
+
+static int handle_io(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+{
+ u64 exit_qualification;
+
+ ++kvm_stat.io_exits;
+ exit_qualification = vmcs_read64(EXIT_QUALIFICATION);
+ kvm_run->exit_reason = KVM_EXIT_IO;
+ if (exit_qualification & 8)
+ kvm_run->io.direction = KVM_EXIT_IO_IN;
+ else
+ kvm_run->io.direction = KVM_EXIT_IO_OUT;
+ kvm_run->io.size = (exit_qualification & 7) + 1;
+ kvm_run->io.string = (exit_qualification & 16) != 0;
+ kvm_run->io.string_down
+ = (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_DF) != 0;
+ kvm_run->io.rep = (exit_qualification & 32) != 0;
+ kvm_run->io.port = exit_qualification >> 16;
+ if (kvm_run->io.string) {
+ if (!get_io_count(vcpu, &kvm_run->io.count))
+ return 1;
+ kvm_run->io.address = vmcs_readl(GUEST_LINEAR_ADDRESS);
+ } else
+ kvm_run->io.value = vcpu->regs[VCPU_REGS_RAX]; /* rax */
+ return 0;
+}
+
+static int handle_invlpg(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+{
+ u64 address = vmcs_read64(EXIT_QUALIFICATION);
+ int instruction_length = vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
+ spin_lock(&vcpu->kvm->lock);
+ vcpu->mmu.inval_page(vcpu, address);
+ spin_unlock(&vcpu->kvm->lock);
+ vmcs_writel(GUEST_RIP, vmcs_readl(GUEST_RIP) + instruction_length);
+ return 1;
+}
+
+static int handle_cr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+{
+ u64 exit_qualification;
+ int cr;
+ int reg;
+
+#ifdef KVM_DEBUG
+ if (guest_cpl() != 0) {
+ vcpu_printf(vcpu, "%s: not supervisor\n", __FUNCTION__);
+ inject_gp(vcpu);
+ return 1;
+ }
+#endif
+
+ exit_qualification = vmcs_read64(EXIT_QUALIFICATION);
+ cr = exit_qualification & 15;
+ reg = (exit_qualification >> 8) & 15;
+ switch ((exit_qualification >> 4) & 3) {
+ case 0: /* mov to cr */
+ switch (cr) {
+ case 0:
+ vcpu_load_rsp_rip(vcpu);
+ set_cr0(vcpu, vcpu->regs[reg]);
+ skip_emulated_instruction(vcpu);
+ return 1;
+ case 3:
+ vcpu_load_rsp_rip(vcpu);
+ set_cr3(vcpu, vcpu->regs[reg]);
+ skip_emulated_instruction(vcpu);
+ return 1;
+ case 4:
+ vcpu_load_rsp_rip(vcpu);
+ set_cr4(vcpu, vcpu->regs[reg]);
+ skip_emulated_instruction(vcpu);
+ return 1;
+ case 8:
+ vcpu_load_rsp_rip(vcpu);
+ set_cr8(vcpu, vcpu->regs[reg]);
+ skip_emulated_instruction(vcpu);
+ return 1;
+ };
+ break;
+ case 1: /*mov from cr*/
+ switch (cr) {
+ case 3:
+ vcpu_load_rsp_rip(vcpu);
+ vcpu->regs[reg] = vcpu->cr3;
+ vcpu_put_rsp_rip(vcpu);
+ skip_emulated_instruction(vcpu);
+ return 1;
+ case 8:
+ printk(KERN_DEBUG "handle_cr: read CR8 "
+ "cpu erratum AA15\n");
+ vcpu_load_rsp_rip(vcpu);
+ vcpu->regs[reg] = vcpu->cr8;
+ vcpu_put_rsp_rip(vcpu);
+ skip_emulated_instruction(vcpu);
+ return 1;
+ }
+ break;
+ case 3: /* lmsw */
+ lmsw(vcpu, (exit_qualification >> LMSW_SOURCE_DATA_SHIFT) & 0x0f);
+
+ skip_emulated_instruction(vcpu);
+ return 1;
+ default:
+ break;
+ }
+ kvm_run->exit_reason = 0;
+ printk(KERN_ERR "kvm: unhandled control register: op %d cr %d\n",
+ (int)(exit_qualification >> 4) & 3, cr);
+ return 0;
+}
+
#ifdef __x86_64__

static void set_efer(struct kvm_vcpu *vcpu, u64 efer)
@@ -1740,6 +2195,26 @@ static void set_efer(struct kvm_vcpu *vc

#endif

+static int handle_interrupt_window(struct kvm_vcpu *vcpu,
+ struct kvm_run *kvm_run)
+{
+ /* Turn off interrupt window reporting. */
+ vmcs_write32(CPU_BASED_VM_EXEC_CONTROL,
+ vmcs_read32(CPU_BASED_VM_EXEC_CONTROL)
+ & ~CPU_BASED_VIRTUAL_INTR_PENDING);
+ return 1;
+}
+
+static int handle_halt(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+{
+ skip_emulated_instruction(vcpu);
+ if (vcpu->irq_summary && (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF))
+ return 1;
+
+ kvm_run->exit_reason = KVM_EXIT_HLT;
+ return 0;
+}
+
/*
* The exit handlers return 1 if the exit was handled fully and guest execution
* may resume. Otherwise they set the kvm_run parameter to indicate what needs
@@ -1747,6 +2222,13 @@ static void set_efer(struct kvm_vcpu *vc
*/
static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu,
struct kvm_run *kvm_run) = {
+ [EXIT_REASON_EXCEPTION_NMI] = handle_exception,
+ [EXIT_REASON_EXTERNAL_INTERRUPT] = handle_external_interrupt,
+ [EXIT_REASON_IO_INSTRUCTION] = handle_io,
+ [EXIT_REASON_INVLPG] = handle_invlpg,
+ [EXIT_REASON_CR_ACCESS] = handle_cr,
+ [EXIT_REASON_PENDING_INTERRUPT] = handle_interrupt_window,
+ [EXIT_REASON_HLT] = handle_halt,
};

static const int kvm_vmx_max_exit_handlers =
-
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