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authorSean Christopherson <sean.j.christopherson@intel.com>2019-01-25 07:41:01 -0800
committerPaolo Bonzini <pbonzini@redhat.com>2019-02-12 13:12:21 +0100
commitfbda0fd31a6d683637f848ba17956048dd0c7e48 (patch)
tree07a35ae1335cd07a6ac1ce4c4d2edfe5eac3b070
parent74dfa2784e961fae66143b811f45105b43c63046 (diff)
downloadlinux-stericsson-fbda0fd31a6d683637f848ba17956048dd0c7e48.tar.gz
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 <sean.j.christopherson@intel.com> Reviewed-by: Jim Mattson <jmattson@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r--arch/x86/kvm/vmx/nested.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 47299e10522f..23a2c1b91389 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)),