From: Sean Christopherson Date: Fri, 25 Jan 2019 15:41:01 +0000 (-0800) Subject: KVM: nVMX: Let the compiler select the reg for holding HOST_RSP X-Git-Tag: v5.4-rc1~1380^2~80 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=fbda0fd31a6d683637f848ba17956048dd0c7e48;p=platform%2Fkernel%2Flinux-rpi.git KVM: nVMX: Let the compiler select the reg for holding HOST_RSP ...and provide an explicit name for the constraint. Naming the input constraint makes the code self-documenting and also avoids the fragility of numerically referring to constraints, e.g. %4 breaks badly whenever the constraints are modified. Explicitly using RDX was inherited from vCPU-run, i.e. completely arbitrary. Even vCPU-run doesn't truly need to explicitly use RDX, but doing so is more robust as vCPU-run needs tight control over its register usage. Note that while the naming "conflict" between host_rsp and HOST_RSP is slightly confusing, the former will be renamed slightly in a future patch, at which point HOST_RSP is absolutely what is desired. Signed-off-by: Sean Christopherson Reviewed-by: Jim Mattson Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 47299e1..23a2c1b 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -2753,9 +2753,8 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu) } asm( - /* Set HOST_RSP */ "sub $%c[wordsize], %%" _ASM_SP "\n\t" /* temporarily adjust RSP for CALL */ - __ex("vmwrite %%" _ASM_SP ", %%" _ASM_DX) "\n\t" + __ex("vmwrite %%" _ASM_SP ", %[HOST_RSP]") "\n\t" "mov %%" _ASM_SP ", %c[host_rsp](%% " _ASM_CX ")\n\t" "add $%c[wordsize], %%" _ASM_SP "\n\t" /* un-adjust RSP */ @@ -2772,7 +2771,8 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu) CC_SET(be) : ASM_CALL_CONSTRAINT, CC_OUT(be) (vm_fail) - : "c"(vmx), "d"((unsigned long)HOST_RSP), + : "c"(vmx), + [HOST_RSP]"r"((unsigned long)HOST_RSP), [loaded_vmcs]"r"(vmx->loaded_vmcs), [launched]"i"(offsetof(struct loaded_vmcs, launched)), [host_rsp]"i"(offsetof(struct vcpu_vmx, host_rsp)),