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| author | Sean Christopherson <sean.j.christopherson@intel.com> | 2019-01-25 07:41:01 -0800 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2019-02-12 13:12:21 +0100 |
| commit | fbda0fd31a6d683637f848ba17956048dd0c7e48 (patch) | |
| tree | 07a35ae1335cd07a6ac1ce4c4d2edfe5eac3b070 /arch/x86/kvm/vmx/nested.c | |
| parent | 74dfa2784e961fae66143b811f45105b43c63046 (diff) | |
| download | lwn-fbda0fd31a6d683637f848ba17956048dd0c7e48.tar.gz lwn-fbda0fd31a6d683637f848ba17956048dd0c7e48.zip | |
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>
Diffstat (limited to 'arch/x86/kvm/vmx/nested.c')
| -rw-r--r-- | arch/x86/kvm/vmx/nested.c | 6 |
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)), |