Commit 6d77dbfc authored by Gleb Natapov's avatar Gleb Natapov Committed by Avi Kivity

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

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: default avatarGleb Natapov <gleb@redhat.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 57bc24cf
...@@ -576,7 +576,6 @@ enum emulation_result { ...@@ -576,7 +576,6 @@ enum emulation_result {
#define EMULTYPE_SKIP (1 << 2) #define EMULTYPE_SKIP (1 << 2)
int emulate_instruction(struct kvm_vcpu *vcpu, int emulate_instruction(struct kvm_vcpu *vcpu,
unsigned long cr2, u16 error_code, int emulation_type); 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_lgdt(struct kvm_vcpu *vcpu, u16 size, unsigned long address);
void realmode_lidt(struct kvm_vcpu *vcpu, u16 size, unsigned long address); void realmode_lidt(struct kvm_vcpu *vcpu, u16 size, unsigned long address);
......
...@@ -2814,11 +2814,8 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code) ...@@ -2814,11 +2814,8 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code)
return 1; return 1;
case EMULATE_DO_MMIO: case EMULATE_DO_MMIO:
++vcpu->stat.mmio_exits; ++vcpu->stat.mmio_exits;
return 0; /* fall through */
case EMULATE_FAIL: 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; return 0;
default: default:
BUG(); BUG();
......
...@@ -1535,7 +1535,7 @@ static int io_interception(struct vcpu_svm *svm) ...@@ -1535,7 +1535,7 @@ static int io_interception(struct vcpu_svm *svm)
string = (io_info & SVM_IOIO_STR_MASK) != 0; string = (io_info & SVM_IOIO_STR_MASK) != 0;
in = (io_info & SVM_IOIO_TYPE_MASK) != 0; in = (io_info & SVM_IOIO_TYPE_MASK) != 0;
if (string || in) 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; port = io_info >> 16;
size = (io_info & SVM_IOIO_SIZE_MASK) >> SVM_IOIO_SIZE_SHIFT; size = (io_info & SVM_IOIO_SIZE_MASK) >> SVM_IOIO_SIZE_SHIFT;
...@@ -2386,16 +2386,12 @@ static int iret_interception(struct vcpu_svm *svm) ...@@ -2386,16 +2386,12 @@ static int iret_interception(struct vcpu_svm *svm)
static int invlpg_interception(struct vcpu_svm *svm) static int invlpg_interception(struct vcpu_svm *svm)
{ {
if (emulate_instruction(&svm->vcpu, 0, 0, 0) != EMULATE_DONE) return emulate_instruction(&svm->vcpu, 0, 0, 0) == EMULATE_DONE;
pr_unimpl(&svm->vcpu, "%s: failed\n", __func__);
return 1;
} }
static int emulate_on_interception(struct vcpu_svm *svm) static int emulate_on_interception(struct vcpu_svm *svm)
{ {
if (emulate_instruction(&svm->vcpu, 0, 0, 0) != EMULATE_DONE) return emulate_instruction(&svm->vcpu, 0, 0, 0) == EMULATE_DONE;
pr_unimpl(&svm->vcpu, "%s: failed\n", __func__);
return 1;
} }
static int cr8_write_interception(struct vcpu_svm *svm) static int cr8_write_interception(struct vcpu_svm *svm)
......
...@@ -3070,7 +3070,7 @@ static int handle_io(struct kvm_vcpu *vcpu) ...@@ -3070,7 +3070,7 @@ static int handle_io(struct kvm_vcpu *vcpu)
++vcpu->stat.io_exits; ++vcpu->stat.io_exits;
if (string || in) 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; port = exit_qualification >> 16;
size = (exit_qualification & 7) + 1; size = (exit_qualification & 7) + 1;
...@@ -3327,22 +3327,7 @@ static int handle_wbinvd(struct kvm_vcpu *vcpu) ...@@ -3327,22 +3327,7 @@ static int handle_wbinvd(struct kvm_vcpu *vcpu)
static int handle_apic_access(struct kvm_vcpu *vcpu) static int handle_apic_access(struct kvm_vcpu *vcpu)
{ {
unsigned long exit_qualification; return emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DONE;
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;
} }
static int handle_task_switch(struct kvm_vcpu *vcpu) static int handle_task_switch(struct kvm_vcpu *vcpu)
...@@ -3554,13 +3539,8 @@ static int handle_invalid_guest_state(struct kvm_vcpu *vcpu) ...@@ -3554,13 +3539,8 @@ static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
goto out; goto out;
} }
if (err != EMULATE_DONE) { if (err != EMULATE_DONE)
vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; return 0;
vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
vcpu->run->internal.ndata = 0;
ret = 0;
goto out;
}
if (signal_pending(current)) if (signal_pending(current))
goto out; goto out;
......
...@@ -3639,24 +3639,6 @@ int emulator_set_dr(int dr, unsigned long value, struct kvm_vcpu *vcpu) ...@@ -3639,24 +3639,6 @@ int emulator_set_dr(int dr, unsigned long value, struct kvm_vcpu *vcpu)
return __kvm_set_dr(vcpu, dr, value); 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) static u64 mk_cr_64(u64 curr_cr, u32 new_val)
{ {
return (curr_cr & ~((1ULL << 32) - 1)) | new_val; return (curr_cr & ~((1ULL << 32) - 1)) | new_val;
...@@ -3863,6 +3845,19 @@ static void inject_emulated_exception(struct kvm_vcpu *vcpu) ...@@ -3863,6 +3845,19 @@ static void inject_emulated_exception(struct kvm_vcpu *vcpu)
kvm_queue_exception(vcpu, ctxt->exception); 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, int emulate_instruction(struct kvm_vcpu *vcpu,
unsigned long cr2, unsigned long cr2,
u16 error_code, u16 error_code,
...@@ -3931,11 +3926,11 @@ int emulate_instruction(struct kvm_vcpu *vcpu, ...@@ -3931,11 +3926,11 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
++vcpu->stat.insn_emulation; ++vcpu->stat.insn_emulation;
if (r) { if (r) {
++vcpu->stat.insn_emulation_fail;
trace_kvm_emulate_insn_failed(vcpu);
if (kvm_mmu_unprotect_page_virt(vcpu, cr2)) if (kvm_mmu_unprotect_page_virt(vcpu, cr2))
return EMULATE_DONE; return EMULATE_DONE;
if (emulation_type & EMULTYPE_SKIP)
return EMULATE_FAIL; return EMULATE_FAIL;
return handle_emulation_failure(vcpu);
} }
} }
...@@ -3960,9 +3955,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu, ...@@ -3960,9 +3955,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
if (kvm_mmu_unprotect_page_virt(vcpu, cr2)) if (kvm_mmu_unprotect_page_virt(vcpu, cr2))
return EMULATE_DONE; return EMULATE_DONE;
trace_kvm_emulate_insn_failed(vcpu); return handle_emulation_failure(vcpu);
kvm_report_emulation_failure(vcpu, "mmio");
return EMULATE_FAIL;
} }
toggle_interruptibility(vcpu, vcpu->arch.emulate_ctxt.interruptibility); 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) ...@@ -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); vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
r = emulate_instruction(vcpu, 0, 0, EMULTYPE_NO_DECODE); r = emulate_instruction(vcpu, 0, 0, EMULTYPE_NO_DECODE);
srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
if (r == EMULATE_DO_MMIO) { if (r != EMULATE_DONE) {
r = 0; r = 0;
goto out; goto out;
} }
......
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