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KVM: inject #UD if instruction emulation fails and exit to userspace

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Do not kill VM when instruction emulation fails. Inject #UD and report
failure to userspace instead. Userspace may choose to reenter guest if
vcpu is in userspace (cpl == 3) in which case guest OS will kill
offending process and continue running.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Gleb Natapov 2010-05-10 11:16:56 +03:00 committed by Avi Kivity
parent 57bc24cfd6
commit 6d77dbfc88
5 changed files with 26 additions and 61 deletions
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1
arch/x86/include/asm/kvm_host.h
View File

@ -576,7 +576,6 @@ enum emulation_result {
#define EMULTYPE_SKIP (1 << 2)
int emulate_instruction(struct kvm_vcpu *vcpu,
unsigned long cr2, u16 error_code, int emulation_type);
void kvm_report_emulation_failure(struct kvm_vcpu *cvpu, const char *context);
void realmode_lgdt(struct kvm_vcpu *vcpu, u16 size, unsigned long address);
void realmode_lidt(struct kvm_vcpu *vcpu, u16 size, unsigned long address);

5
arch/x86/kvm/mmu.c
View File

@ -2814,11 +2814,8 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code)
return 1;
case EMULATE_DO_MMIO:
++vcpu->stat.mmio_exits;
return 0;
/* fall through */
case EMULATE_FAIL:
vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
vcpu->run->internal.ndata = 0;
return 0;
default:
BUG();

10
arch/x86/kvm/svm.c
View File

@ -1535,7 +1535,7 @@ static int io_interception(struct vcpu_svm *svm)
string = (io_info & SVM_IOIO_STR_MASK) != 0;
in = (io_info & SVM_IOIO_TYPE_MASK) != 0;
if (string || in)
return !(emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DO_MMIO);
return emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DONE;
port = io_info >> 16;
size = (io_info & SVM_IOIO_SIZE_MASK) >> SVM_IOIO_SIZE_SHIFT;
@ -2386,16 +2386,12 @@ static int iret_interception(struct vcpu_svm *svm)
static int invlpg_interception(struct vcpu_svm *svm)
{
if (emulate_instruction(&svm->vcpu, 0, 0, 0) != EMULATE_DONE)
pr_unimpl(&svm->vcpu, "%s: failed\n", __func__);
return 1;
return emulate_instruction(&svm->vcpu, 0, 0, 0) == EMULATE_DONE;
}
static int emulate_on_interception(struct vcpu_svm *svm)
{
if (emulate_instruction(&svm->vcpu, 0, 0, 0) != EMULATE_DONE)
pr_unimpl(&svm->vcpu, "%s: failed\n", __func__);
return 1;
return emulate_instruction(&svm->vcpu, 0, 0, 0) == EMULATE_DONE;
}
static int cr8_write_interception(struct vcpu_svm *svm)

28
arch/x86/kvm/vmx.c
View File

@ -3070,7 +3070,7 @@ static int handle_io(struct kvm_vcpu *vcpu)
++vcpu->stat.io_exits;
if (string || in)
return !(emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DO_MMIO);
return emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DONE;
port = exit_qualification >> 16;
size = (exit_qualification & 7) + 1;
@ -3327,22 +3327,7 @@ static int handle_wbinvd(struct kvm_vcpu *vcpu)
static int handle_apic_access(struct kvm_vcpu *vcpu)
{
unsigned long exit_qualification;
enum emulation_result er;
unsigned long offset;
exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
offset = exit_qualification & 0xffful;
er = emulate_instruction(vcpu, 0, 0, 0);
if (er != EMULATE_DONE) {
printk(KERN_ERR
"Fail to handle apic access vmexit! Offset is 0x%lx\n",
offset);
return -ENOEXEC;
}
return 1;
return emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DONE;
}
static int handle_task_switch(struct kvm_vcpu *vcpu)
@ -3554,13 +3539,8 @@ static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
goto out;
}
if (err != EMULATE_DONE) {
vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
vcpu->run->internal.ndata = 0;
ret = 0;
goto out;
}
if (err != EMULATE_DONE)
return 0;
if (signal_pending(current))
goto out;

43
arch/x86/kvm/x86.c
View File

@ -3639,24 +3639,6 @@ int emulator_set_dr(int dr, unsigned long value, struct kvm_vcpu *vcpu)
return __kvm_set_dr(vcpu, dr, value);
}
void kvm_report_emulation_failure(struct kvm_vcpu *vcpu, const char *context)
{
u8 opcodes[4];
unsigned long rip = kvm_rip_read(vcpu);
unsigned long rip_linear;
if (!printk_ratelimit())
return;
rip_linear = rip + get_segment_base(vcpu, VCPU_SREG_CS);
kvm_read_guest_virt(rip_linear, (void *)opcodes, 4, vcpu, NULL);
printk(KERN_ERR "emulation failed (%s) rip %lx %02x %02x %02x %02x\n",
context, rip, opcodes[0], opcodes[1], opcodes[2], opcodes[3]);
}
EXPORT_SYMBOL_GPL(kvm_report_emulation_failure);
static u64 mk_cr_64(u64 curr_cr, u32 new_val)
{
return (curr_cr & ~((1ULL << 32) - 1)) | new_val;
@ -3863,6 +3845,19 @@ static void inject_emulated_exception(struct kvm_vcpu *vcpu)
kvm_queue_exception(vcpu, ctxt->exception);
}
static int handle_emulation_failure(struct kvm_vcpu *vcpu)
{
struct x86_emulate_ctxt *ctxt = &vcpu->arch.emulate_ctxt;
++vcpu->stat.insn_emulation_fail;
trace_kvm_emulate_insn_failed(vcpu);
vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
vcpu->run->internal.ndata = 0;
kvm_queue_exception(vcpu, UD_VECTOR);
return EMULATE_FAIL;
}
int emulate_instruction(struct kvm_vcpu *vcpu,
unsigned long cr2,
u16 error_code,
@ -3931,11 +3926,11 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
++vcpu->stat.insn_emulation;
if (r) {
++vcpu->stat.insn_emulation_fail;
trace_kvm_emulate_insn_failed(vcpu);
if (kvm_mmu_unprotect_page_virt(vcpu, cr2))
return EMULATE_DONE;
return EMULATE_FAIL;
if (emulation_type & EMULTYPE_SKIP)
return EMULATE_FAIL;
return handle_emulation_failure(vcpu);
}
}
@ -3960,9 +3955,7 @@ restart:
if (kvm_mmu_unprotect_page_virt(vcpu, cr2))
return EMULATE_DONE;
trace_kvm_emulate_insn_failed(vcpu);
kvm_report_emulation_failure(vcpu, "mmio");
return EMULATE_FAIL;
return handle_emulation_failure(vcpu);
}
toggle_interruptibility(vcpu, vcpu->arch.emulate_ctxt.interruptibility);
@ -4798,7 +4791,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
r = emulate_instruction(vcpu, 0, 0, EMULTYPE_NO_DECODE);
srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
if (r == EMULATE_DO_MMIO) {
if (r != EMULATE_DONE) {
r = 0;
goto out;
}