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From: Jim Mattson <jmattson@google.com>
To: kvm@vger.kernel.org, pbonzini@redhat.com
Cc: Jim Mattson <jmattson@google.com>
Subject: [PATCH] KVM: VMX: Move VM-exit RSB stuffing out of line
Date: Wed, 22 Jun 2022 15:24:08 -0700	[thread overview]
Message-ID: <20220622222408.518889-1-jmattson@google.com> (raw)

RSB-stuffing after VM-exit is only needed for legacy CPUs without
eIBRS. Move the RSB-stuffing code out of line.

Preserve the non-sensical correlation of RSB-stuffing with retpoline.

Signed-off-by: Jim Mattson <jmattson@google.com>
---
 arch/x86/kvm/vmx/vmenter.S | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S
index 435c187927c4..39009a4c86bd 100644
--- a/arch/x86/kvm/vmx/vmenter.S
+++ b/arch/x86/kvm/vmx/vmenter.S
@@ -76,7 +76,12 @@ SYM_FUNC_END(vmx_vmenter)
  */
 SYM_FUNC_START(vmx_vmexit)
 #ifdef CONFIG_RETPOLINE
-	ALTERNATIVE "jmp .Lvmexit_skip_rsb", "", X86_FEATURE_RETPOLINE
+	ALTERNATIVE "", "jmp .Lvmexit_stuff_rsb", X86_FEATURE_RETPOLINE
+#endif
+.Lvmexit_return:
+	RET
+#ifdef CONFIG_RETPOLINE
+.Lvmexit_stuff_rsb:
 	/* Preserve guest's RAX, it's used to stuff the RSB. */
 	push %_ASM_AX
 
@@ -87,9 +92,8 @@ SYM_FUNC_START(vmx_vmexit)
 	or $1, %_ASM_AX
 
 	pop %_ASM_AX
-.Lvmexit_skip_rsb:
+	jmp .Lvmexit_return
 #endif
-	RET
 SYM_FUNC_END(vmx_vmexit)
 
 /**
-- 
2.37.0.rc0.104.g0611611a94-goog


             reply	other threads:[~2022-06-22 22:24 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-22 22:24 Jim Mattson [this message]
2022-06-27 15:08 ` [PATCH] KVM: VMX: Move VM-exit RSB stuffing out of line Sean Christopherson
2022-06-27 17:59   ` Jim Mattson

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