[PATCH 6.12 229/567] KVM: nSVM: Clear exit_code_hi in VMCB when synthesizing nested VM-Exits

Greg Kroah-Hartman
2026-01-06T17:26:53Z

From: Sean Christopherson <seanjc@google.com>

commit da01f64e7470988f8607776aa7afa924208863fb upstream.

Explicitly clear exit_code_hi in the VMCB when synthesizing "normal"
nested VM-Exits, as the full exit code is a 64-bit value (spoiler alert),
and all exit codes for non-failing VMRUN use only bits 31:0.

Cc: Jim Mattson <jmattson@google.com>
Cc: Yosry Ahmed <yosry.ahmed@linux.dev>
Cc: stable@vger.kernel.org
Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Link: https://patch.msgid.link/20251113225621.1688428-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kvm/svm/svm.c | 2 ++
arch/x86/kvm/svm/svm.h | 7 ++++---
2 files changed, 6 insertions(+), 3 deletions(-)

--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2702,6 +2702,7 @@ static bool check_selective_cr0_intercep

if (cr0 ^ val) {
svm->vmcb->control.exit_code = SVM_EXIT_CR0_SEL_WRITE;
+ svm->vmcb->control.exit_code_hi = 0;
ret = (nested_svm_exit_handled(svm) == NESTED_EXIT_DONE);
}

@@ -4749,6 +4750,7 @@ static int svm_check_intercept(struct kv
if (static_cpu_has(X86_FEATURE_NRIPS))
vmcb->control.next_rip = info->next_rip;
vmcb->control.exit_code = icpt_info.exit_code;
+ vmcb->control.exit_code_hi = 0;
vmexit = nested_svm_exit_handled(svm);

ret = (vmexit == NESTED_EXIT_DONE) ? X86EMUL_INTERCEPTED
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -662,9 +662,10 @@ int nested_svm_vmexit(struct vcpu_svm *s

static inline int nested_svm_simple_vmexit(struct vcpu_svm *svm, u32 exit_code)
{
- svm->vmcb->control.exit_code = exit_code;
- svm->vmcb->control.exit_info_1 = 0;
- svm->vmcb->control.exit_info_2 = 0;
+ svm->vmcb->control.exit_code = exit_code;
+ svm->vmcb->control.exit_code_hi = 0;
+ svm->vmcb->control.exit_info_1 = 0;
+ svm->vmcb->control.exit_info_2 = 0;
return nested_svm_vmexit(svm);
}