linux-kernel - Re: [PATCH] kvm: add proper frame pointer logic for vmx

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Date:   Tue, 15 Jan 2019 08:13:22 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Qian Cai <cai@....pw>, rkrcmar@...hat.com
Cc:     sean.j.christopherson@...el.com, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, hpa@...or.com, x86@...nel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kvm: add proper frame pointer logic for vmx

On 15/01/19 08:04, Qian Cai wrote:
> 
> 
> On 1/15/19 1:44 AM, Qian Cai wrote:
>> compilation warning since v5.0-rc1,
>>
>> arch/x86/kvm/vmx/vmx.o: warning: objtool: vmx_vcpu_run.part.17()+0x3171:
>> call without frame pointer save/setup
>>
>> Fixes: 453eafbe65f (KVM: VMX: Move VM-Enter + VM-Exit handling to
>> non-inline sub-routines)
> 
> Oops, wrong fix. Back to square one.
> 

Hmm, maybe like this:

diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S
index bcef2c7e9bc4..33122fa9d4bd 100644
--- a/arch/x86/kvm/vmx/vmenter.S
+++ b/arch/x86/kvm/vmx/vmenter.S
@@ -26,19 +26,17 @@ ENTRY(vmx_vmenter)
 	ret

 2:	vmlaunch
+3:
 	ret

-3:	cmpb $0, kvm_rebooting
-	jne 4f
-	call kvm_spurious_fault
-4:	ret
-
 	.pushsection .fixup, "ax"
-5:	jmp 3b
+4:	cmpb $0, kvm_rebooting
+	jne 3b
+	jmp kvm_spurious_fault
 	.popsection

-	_ASM_EXTABLE(1b, 5b)
-	_ASM_EXTABLE(2b, 5b)
+	_ASM_EXTABLE(1b, 4b)
+	_ASM_EXTABLE(2b, 4b)

 ENDPROC(vmx_vmenter)


Paolo