[PATCH v2 4/6] KVM: SVM: Handle MMIO during vectroing error

Ivan Orlov
2024-11-11T10:28:14Z

Handle MMIO during vectoring error in check_emulate_instruction to
prevent infinite loop on SVM and eliminate the difference in how the
situation when the guest accesses MMIO during vectoring is handled on
SVM and VMX.

Signed-off-by: Ivan Orlov <iorlov@amazon.com>
---
V1 -> V2:
- Detect the unhandleable vectoring error in svm_check_emulate_instruction
instead of handling it in the common MMU code (which is specific for
cached MMIO)

arch/x86/kvm/svm/svm.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index c1e29307826b..b69f0f98c576 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4797,9 +4797,16 @@ 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)
{
- bool smep, smap, is_user;
+ bool smep, smap, is_user, is_vect;
u64 error_code;

+ is_vect = to_svm(vcpu)->vmcb->control.exit_int_info &
+ SVM_EXITINTINFO_TYPE_MASK;
+
+ /* Emulation is not possible when MMIO happens during event vectoring. */
+ if (kvm_is_emul_type_mmio(emul_type) && is_vect)
+ return X86EMUL_UNHANDLEABLE_VECTORING_IO;
+
/* Emulation is always possible when KVM has access to all guest state. */
if (!sev_guest(vcpu->kvm))
return X86EMUL_CONTINUE;
--
2.43.0