linux-kernel - [PATCH v2 5/5] KVM: x86: Don't check kvm_rebooting in __kvm_handle_fault_on

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Date:   Fri, 19 Jul 2019 13:41:10 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, Josh Poimboeuf <jpoimboe@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     "H. Peter Anvin" <hpa@...or.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 5/5] KVM: x86: Don't check kvm_rebooting in __kvm_handle_fault_on_reboot()

Remove the kvm_rebooting check from VMX/SVM instruction exception fixup
now that kvm_spurious_fault() conditions its BUG() on !kvm_rebooting.
Because the 'cleanup_insn' functionally is also gone, deferring to
kvm_spurious_fault() means __kvm_handle_fault_on_reboot() can eliminate
its .fixup code entirely and have its exception table entry branch
directly to the call to kvm_spurious_fault().

Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/include/asm/kvm_host.h | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 92c59cd923b6..a5ae5562ce0a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1511,13 +1511,7 @@ asmlinkage void kvm_spurious_fault(void);
 	"667: \n\t"							\
 	"call	kvm_spurious_fault \n\t"				\
 	"668: \n\t"							\
-	".pushsection .fixup, \"ax\" \n\t"				\
-	"700: \n\t"							\
-	"cmpb	$0, kvm_rebooting\n\t"					\
-	"je	667b \n\t"						\
-	"jmp	668b \n\t"						\
-	".popsection \n\t"						\
-	_ASM_EXTABLE(666b, 700b)
+	_ASM_EXTABLE(666b, 667b)
 
 #define KVM_ARCH_WANT_MMU_NOTIFIER
 int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end);
-- 
2.22.0