linux-kernel - [PATCH 2/4] KVM: SVM: Use KVM's snapshot of the host's XCR0 for SEV-ES host state

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Date: Tue, 23 Apr 2024 15:15:19 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/4] KVM: SVM: Use KVM's snapshot of the host's XCR0 for
 SEV-ES host state

Use KVM's snapshot of the host's XCR0 when stuffing SEV-ES host state
instead of reading XCR0 from hardware.  XCR0 is only written during
boot, i.e. won't change while KVM is running (and KVM at large is hosed
if that doesn't hold true).

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/sev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 71f1518f0ca1..c56070991a58 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3249,7 +3249,7 @@ void sev_es_prepare_switch_to_guest(struct vcpu_svm *svm, struct sev_es_save_are
 	 * isn't saved by VMRUN, that isn't already saved by VMSAVE (performed
 	 * by common SVM code).
 	 */
-	hostsa->xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
+	hostsa->xcr0 = kvm_host.xcr0;
 	hostsa->pkru = read_pkru();
 	hostsa->xss = kvm_host.xss;
 
-- 
2.44.0.769.g3c40516874-goog