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KVM: x86: Calculate the supported xcr0 mask at load time

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Add a new global variable, supported_xcr0, to track which xcr0 bits can
be exposed to the guest instead of calculating the mask on every call.
The supported bits are constant for a given instance of KVM.

This paves the way toward eliminating the ->mpx_supported() call in
kvm_mpx_supported(), e.g. eliminates multiple retpolines in VMX's nested
VM-Enter path, and eventually toward eliminating ->mpx_supported()
altogether.

No functional change intended.

Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson
2020-03-02 15:56:23 -08:00
committed by Paolo Bonzini
parent 2ef7619d43
commit cfc481810c
5 changed files with 27 additions and 32 deletions
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14
arch/x86/kvm/x86.c
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@@ -181,6 +181,11 @@ struct kvm_shared_msrs {
static struct kvm_shared_msrs_global __read_mostly shared_msrs_global;
static struct kvm_shared_msrs __percpu *shared_msrs;
#define KVM_SUPPORTED_XCR0 (XFEATURE_MASK_FP | XFEATURE_MASK_SSE \
| XFEATURE_MASK_YMM | XFEATURE_MASK_BNDREGS \
| XFEATURE_MASK_BNDCSR | XFEATURE_MASK_AVX512 \
| XFEATURE_MASK_PKRU)
static u64 __read_mostly host_xss;
struct kvm_stats_debugfs_item debugfs_entries[] = {
@@ -227,6 +232,8 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
};
u64 __read_mostly host_xcr0;
u64 __read_mostly supported_xcr0;
EXPORT_SYMBOL_GPL(supported_xcr0);
struct kmem_cache *x86_fpu_cache;
EXPORT_SYMBOL_GPL(x86_fpu_cache);
@@ -4114,8 +4121,7 @@ static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu,
* CPUID leaf 0xD, index 0, EDX:EAX. This is for compatibility
* with old userspace.
*/
if (xstate_bv & ~kvm_supported_xcr0() ||
mxcsr & ~mxcsr_feature_mask)
if (xstate_bv & ~supported_xcr0 || mxcsr & ~mxcsr_feature_mask)
return -EINVAL;
load_xsave(vcpu, (u8 *)guest_xsave->region);
} else {
@@ -7352,8 +7358,10 @@ int kvm_arch_init(void *opaque)
perf_register_guest_info_callbacks(&kvm_guest_cbs);
if (boot_cpu_has(X86_FEATURE_XSAVE))
if (boot_cpu_has(X86_FEATURE_XSAVE)) {
host_xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
supported_xcr0 = host_xcr0 & KVM_SUPPORTED_XCR0;
}
kvm_lapic_init();
if (pi_inject_timer == -1)