linux-kernel - [PATCH 16/16] KVM: SVM: Use "standard" stgi() helper when disabling SVM

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Message-ID: <20221201232655.290720-17-seanjc@google.com>
Date:   Thu,  1 Dec 2022 23:26:55 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, Andrew Cooper <Andrew.Cooper3@...rix.com>
Subject: [PATCH 16/16] KVM: SVM: Use "standard" stgi() helper when disabling SVM

Now that kvm_rebooting is guaranteed to be true prior to disabling SVM
in an emergency, use the existing stgi() helper instead of open coding
STGI.  In effect, eat faults on STGI if and only if kvm_rebooting==true.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/svm.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 08ed4679903a..72899a61f708 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -579,13 +579,9 @@ static inline void kvm_cpu_svm_disable(void)
 	if (efer & EFER_SVME) {
 		/*
 		 * Force GIF=1 prior to disabling SVM, e.g. to ensure INIT and
-		 * NMI aren't blocked.  Eat faults on STGI, as it #UDs if SVM
-		 * isn't enabled and SVM can be disabled by an NMI callback.
+		 * NMI aren't blocked.
 		 */
-		asm_volatile_goto("1: stgi\n\t"
-				  _ASM_EXTABLE(1b, %l[fault])
-				  ::: "memory" : fault);
-fault:
+		stgi();
 		wrmsrl(MSR_EFER, efer & ~EFER_SVME);
 	}
 }
-- 
2.39.0.rc0.267.gcb52ba06e7-goog