If the guest requests string I/O from the hypervisor via VMGEXIT,
SW_EXITINFO2 will contain the REP count. However, sev_es_string_io
was incorrectly treating it as the size of the GHCB buffer in
bytes.
This fixes the "outsw" test in the experimental SEV tests of
kvm-unit-tests.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 7ed9abfe8e9f ("KVM: SVM: Support string IO operations for an SEV-ES guest")
Reported-by: Marc Orr <marcorr@xxxxxxxxxx>
Tested-by: Marc Orr <marcorr@xxxxxxxxxx>
Reviewed-by: Marc Orr <marcorr@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/svm/sev.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index e672493b5d8d..efd207fd335e 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2579,11 +2579,20 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in)
{
- if (!setup_vmgexit_scratch(svm, in, svm->vmcb->control.exit_info_2))
+ int count;
+ int bytes;
+
+ if (svm->vmcb->control.exit_info_2 > INT_MAX)
+ return -EINVAL;
+
+ count = svm->vmcb->control.exit_info_2;
+ if (unlikely(check_mul_overflow(count, size, &bytes)))
+ return -EINVAL;
+
+ if (!setup_vmgexit_scratch(svm, in, bytes))
return -EINVAL;
- return kvm_sev_es_string_io(&svm->vcpu, size, port,
- svm->ghcb_sa, svm->ghcb_sa_len / size, in);
+ return kvm_sev_es_string_io(&svm->vcpu, size, port, svm->ghcb_sa, count, in);
}
void sev_es_init_vmcb(struct vcpu_svm *svm)
--
2.27.0
