linux-kernel - [PATCH 1/8] KVM: SVM: Create a stack frame in __svm_vcpu

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Date: Fri, 23 Feb 2024 12:42:26 -0800
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, 
	Tom Lendacky <thomas.lendacky@....com>, Michael Roth <michael.roth@....com>, 
	Alexey Kardashevskiy <aik@....com>
Subject: [PATCH 1/8] KVM: SVM: Create a stack frame in __svm_vcpu_run() for unwinding

Unconditionally create a stack frame in __svm_vcpu_run() to play nice with
unwinding via frame pointers, at least until the point where RBP is loaded
with the guest's value.  Don't bother conditioning the code on
CONFIG_FRAME_POINTER=y, as RBP needs to be saved and restored anyways (due
to it being clobbered with the guest's value); omitting the "MOV RSP, RBP"
is not worth the extra #ifdef.

Creating a stack frame will allow removing the OBJECT_FILES_NON_STANDARD
tag from vmenter.S once __svm_sev_es_vcpu_run() is fixed to not stomp all
over RBP for no reason.

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

diff --git a/arch/x86/kvm/svm/vmenter.S b/arch/x86/kvm/svm/vmenter.S
index 9499f9c6b077..ee5d5a30da88 100644
--- a/arch/x86/kvm/svm/vmenter.S
+++ b/arch/x86/kvm/svm/vmenter.S
@@ -99,6 +99,7 @@
  */
 SYM_FUNC_START(__svm_vcpu_run)
 	push %_ASM_BP
+	mov  %_ASM_SP, %_ASM_BP
 #ifdef CONFIG_X86_64
 	push %r15
 	push %r14
-- 
2.44.0.rc0.258.g7320e95886-goog