[PATCH 7/8] KVM: x86: Allow marking an exception as reinjected

Joerg Roedel
2010-04-22T10:33:43Z

This patch adds logic to kvm/x86 which allows to mark an
injected exception as reinjected. This allows to remove an
ugly hack from svm_complete_interrupts that prevented
exceptions from being reinjected at all in the nested case.
The hack was necessary because an reinjected exception into
the nested guest could cause a nested vmexit emulation. But
reinjected exceptions must not intercept. The downside of
the hack is that a exception that in injected could get
lost.
This patch fixes the problem and puts the code for it into
generic x86 files because. Nested-VMX will likely have the
same problem and could reuse the code.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
---
arch/x86/include/asm/kvm_host.h | 6 +++++-
arch/x86/kvm/svm.c | 12 ++++++------
arch/x86/kvm/vmx.c | 3 ++-
arch/x86/kvm/x86.c | 23 +++++++++++++++++++----
4 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 357573a..3f0007b 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -312,6 +312,7 @@ struct kvm_vcpu_arch {
struct kvm_queued_exception {
bool pending;
bool has_error_code;
+ bool reinject;
u8 nr;
u32 error_code;
} exception;
@@ -514,7 +515,8 @@ struct kvm_x86_ops {
void (*set_irq)(struct kvm_vcpu *vcpu);
void (*set_nmi)(struct kvm_vcpu *vcpu);
void (*queue_exception)(struct kvm_vcpu *vcpu, unsigned nr,
- bool has_error_code, u32 error_code);
+ bool has_error_code, u32 error_code,
+ bool reinject);
int (*interrupt_allowed)(struct kvm_vcpu *vcpu);
int (*nmi_allowed)(struct kvm_vcpu *vcpu);
bool (*get_nmi_mask)(struct kvm_vcpu *vcpu);
@@ -617,6 +619,8 @@ void kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags);

void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr);
void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
+void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr);
+void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
void kvm_inject_page_fault(struct kvm_vcpu *vcpu, unsigned long cr2,
u32 error_code);
bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 65fc114..30e49fe 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -338,7 +338,8 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
}

static void svm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr,
- bool has_error_code, u32 error_code)
+ bool has_error_code, u32 error_code,
+ bool reinject)
{
struct vcpu_svm *svm = to_svm(vcpu);

@@ -346,7 +347,8 @@ static void svm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr,
* If we are within a nested VM we'd better #VMEXIT and let the guest
* handle the exception
*/
- if (nested_svm_check_exception(svm, nr, has_error_code, error_code))
+ if (!reinject &&
+ nested_svm_check_exception(svm, nr, has_error_code, error_code))
return;

if (nr == BP_VECTOR && !svm_has(SVM_FEATURE_NRIP)) {
@@ -2918,8 +2920,6 @@ static void svm_complete_interrupts(struct vcpu_svm *svm)
svm->vcpu.arch.nmi_injected = true;
break;
case SVM_EXITINTINFO_TYPE_EXEPT:
- if (is_nested(svm))
- break;
/*
* In case of software exceptions, do not reinject the vector,
* but re-execute the instruction instead. Rewind RIP first
@@ -2935,10 +2935,10 @@ static void svm_complete_interrupts(struct vcpu_svm *svm)
}
if (exitintinfo & SVM_EXITINTINFO_VALID_ERR) {
u32 err = svm->vmcb->control.exit_int_info_err;
- kvm_queue_exception_e(&svm->vcpu, vector, err);
+ kvm_requeue_exception_e(&svm->vcpu, vector, err);

} else
- kvm_queue_exception(&svm->vcpu, vector);
+ kvm_requeue_exception(&svm->vcpu, vector);
break;
case SVM_EXITINTINFO_TYPE_INTR:
kvm_queue_interrupt(&svm->vcpu, vector, false);
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index dc023bc..285fe1a 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -919,7 +919,8 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
}

static void vmx_queue_exception(struct kvm_vcpu *vcpu, unsigned nr,
- bool has_error_code, u32 error_code)
+ bool has_error_code, u32 error_code,
+ bool reinject)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
u32 intr_info = nr | INTR_INFO_VALID_MASK;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c2c3c29..9c183cd 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -265,7 +265,8 @@ static int exception_class(int vector)
}

static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
- unsigned nr, bool has_error, u32 error_code)
+ unsigned nr, bool has_error, u32 error_code,
+ bool reinject)
{
u32 prev_nr;
int class1, class2;
@@ -276,6 +277,7 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
vcpu->arch.exception.has_error_code = has_error;
vcpu->arch.exception.nr = nr;
vcpu->arch.exception.error_code = error_code;
+ vcpu->arch.exception.reinject = true;
return;
}

@@ -304,10 +306,16 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,

void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr)
{
- kvm_multiple_exception(vcpu, nr, false, 0);
+ kvm_multiple_exception(vcpu, nr, false, 0, false);
}
EXPORT_SYMBOL_GPL(kvm_queue_exception);

+void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr)
+{
+ kvm_multiple_exception(vcpu, nr, false, 0, true);
+}
+EXPORT_SYMBOL_GPL(kvm_requeue_exception);
+
void kvm_inject_page_fault(struct kvm_vcpu *vcpu, unsigned long addr,
u32 error_code)
{
@@ -324,10 +332,16 @@ EXPORT_SYMBOL_GPL(kvm_inject_nmi);

void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code)
{
- kvm_multiple_exception(vcpu, nr, true, error_code);
+ kvm_multiple_exception(vcpu, nr, true, error_code, false);
}
EXPORT_SYMBOL_GPL(kvm_queue_exception_e);

+void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code)
+{
+ kvm_multiple_exception(vcpu, nr, true, error_code, true);
+}
+EXPORT_SYMBOL_GPL(kvm_requeue_exception_e);
+
/*
* Checks if cpl <= required_cpl; if true, return true. Otherwise queue
* a #GP and return false.
@@ -4404,7 +4418,8 @@ static void inject_pending_event(struct kvm_vcpu *vcpu)
vcpu->arch.exception.error_code);
kvm_x86_ops->queue_exception(vcpu, vcpu->arch.exception.nr,
vcpu->arch.exception.has_error_code,
- vcpu->arch.exception.error_code);
+ vcpu->arch.exception.error_code,
+ vcpu->arch.exception.reinject);
return;
}

--
1.7.0.4