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Subject[PATCH 4/8] KVM: SVM: Clobber RAX instead of RBX when discarding spec_ctrl_intercepted
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POP @spec_ctrl_intercepted into RAX instead of RBX when discarding it from
the stack so that __svm_sev_es_vcpu_run() doesn't modify any non-volatile
registers. __svm_sev_es_vcpu_run() doesn't return a value, and RAX is
already are clobbered multiple times in the #VMEXIT path.

This will allowing using the host save area to save/restore non-volatile
registers in __svm_sev_es_vcpu_run().

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/svm/vmenter.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm/vmenter.S b/arch/x86/kvm/svm/vmenter.S
index 0026b4a56d25..edbaadaacba7 100644
--- a/arch/x86/kvm/svm/vmenter.S
+++ b/arch/x86/kvm/svm/vmenter.S
@@ -350,8 +350,8 @@ SYM_FUNC_START(__svm_sev_es_vcpu_run)
*/
UNTRAIN_RET_VM

- /* "Pop" @spec_ctrl_intercepted. */
- pop %rbx
+ /* "Pop" and discard @spec_ctrl_intercepted. */
+ pop %rax

pop %rbx

--
2.44.0.rc0.258.g7320e95886-goog

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