KVM: VMX: Let the compiler save/load RDX during vCPU-run (6f7c6d23) · Commits · 戴 / test

Per commit ("KVM: VMX: Let gcc to choose which registers to save (x86_64)"), the only reason RDX is saved/loaded to/from the stack is because it was specified as an input, i.e. couldn't be marked as clobbered (ignoring the fact that "saving" it to a dummy output would indirectly mark it as clobbered). Now that RDX is no longer an input, clobber it. Reviewed-by:

Jim Mattson <jmattson@google.com> Signed-off-by:

Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/vmx.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -6377,7 +6377,7 @@ static void __vmx_vcpu_run(struct kvm_vcpu vcpu, struct vcpu_vmx vmx)

		asm(
		/* Store host registers */
		"push %%" _ASM_DX "; push %%" _ASM_BP ";"
		"push %%" _ASM_BP " \n\t"
		"sub $%c[wordsize], %%" _ASM_SP "\n\t" /* placeholder for guest RCX */
		"push %%" _ASM_CX " \n\t"
		"sub $%c[wordsize], %%" _ASM_SP "\n\t" /* temporarily adjust RSP for CALL */
		@@ -6481,7 +6481,7 @@ static void __vmx_vcpu_run(struct kvm_vcpu vcpu, struct vcpu_vmx vmx)
		"xor %%esi, %%esi \n\t"
		"xor %%edi, %%edi \n\t"
		"xor %%ebp, %%ebp \n\t"
		"pop %%" _ASM_BP "; pop %%" _ASM_DX " \n\t"
		"pop %%" _ASM_BP " \n\t"
		: ASM_CALL_CONSTRAINT, "=S"((int){0})
		: "c"(vmx), "S"(evmcs_rsp),
		[launched]"i"(offsetof(struct vcpu_vmx, __launched)),
		@@ -6509,10 +6509,10 @@ static void __vmx_vcpu_run(struct kvm_vcpu vcpu, struct vcpu_vmx vmx)
		[wordsize]"i"(sizeof(ulong))
		: "cc", "memory"
		#ifdef CONFIG_X86_64
		, "rax", "rbx", "rdi"
		, "rax", "rbx", "rdx", "rdi"
		, "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15"
		#else
		, "eax", "ebx", "edi"
		, "eax", "ebx", "edx", "edi"
		#endif
		);
		}

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