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KVM: SVM: Handle event vectoring error in check_emulate_instruction()

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Detect unhandleable vectoring in check_emulate_instruction() to prevent
infinite retry loops on SVM, and to eliminate the main differences in how
VM-Exits during event vectoring are handled on SVM versus VMX.  E.g. if
the vCPU puts its IDT in emulated MMIO memory and generates an event,
without the check_emulate_instruction() change, SVM will re-inject the
event and resume the guest, and effectively put the vCPU into an infinite
loop.

Signed-off-by: Ivan Orlov <iorlov@amazon.com>
Link: https://lore.kernel.org/r/20241217181458.68690-6-iorlov@amazon.com
[sean: grab "svm" locally, massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Ivan Orlov
2024-12-17 18:14:56 +00:00
committed by Sean Christopherson
parent 47ef3ef843
commit 7bd7ff9911
1 changed files with 7 additions and 1 deletions
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8
arch/x86/kvm/svm/svm.c
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@@ -4789,9 +4789,15 @@ static void svm_enable_smi_window(struct kvm_vcpu *vcpu)
static int svm_check_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
void *insn, int insn_len)
{
struct vcpu_svm *svm = to_svm(vcpu);
bool smep, smap, is_user;
u64 error_code;
/* Check that emulation is possible during event vectoring */
if ((svm->vmcb->control.exit_int_info & SVM_EXITINTINFO_TYPE_MASK) &&
!kvm_can_emulate_event_vectoring(emul_type))
return X86EMUL_UNHANDLEABLE_VECTORING;
/* Emulation is always possible when KVM has access to all guest state. */
if (!sev_guest(vcpu->kvm))
return X86EMUL_CONTINUE;
@@ -4888,7 +4894,7 @@ static int svm_check_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
* In addition, don't apply the erratum workaround if the #NPF occurred
* while translating guest page tables (see below).
*/
error_code = to_svm(vcpu)->vmcb->control.exit_info_1;
error_code = svm->vmcb->control.exit_info_1;
if (error_code & (PFERR_GUEST_PAGE_MASK | PFERR_FETCH_MASK))
goto resume_guest;