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kvm: x86: Disable RDMSR interception of IA32_XFD_ERR

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This saves one unnecessary VM-exit in guest #NM handler, given that the
MSR is already restored with the guest value before the guest is resumed.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jing Liu <jing2.liu@intel.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
Message-Id: <20220105123532.12586-15-yang.zhong@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Jing Liu 2022-01-05 04:35:25 -08:00 committed by Paolo Bonzini
parent 548e83650a
commit 61f208134a
2 changed files with 7 additions and 1 deletions
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6
arch/x86/kvm/vmx/vmx.c
View File

@ -162,6 +162,7 @@ static u32 vmx_possible_passthrough_msrs[MAX_POSSIBLE_PASSTHROUGH_MSRS] = {
MSR_FS_BASE,
MSR_GS_BASE,
MSR_KERNEL_GS_BASE,
MSR_IA32_XFD_ERR,
#endif
MSR_IA32_SYSENTER_CS,
MSR_IA32_SYSENTER_ESP,
@ -7288,6 +7289,11 @@ static void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
}
}
if (kvm_cpu_cap_has(X86_FEATURE_XFD))
vmx_set_intercept_for_msr(vcpu, MSR_IA32_XFD_ERR, MSR_TYPE_R,
!guest_cpuid_has(vcpu, X86_FEATURE_XFD));
set_cr4_guest_host_mask(vmx);
vmx_write_encls_bitmap(vcpu, NULL);

2
arch/x86/kvm/vmx/vmx.h
View File

@ -349,7 +349,7 @@ struct vcpu_vmx {
struct lbr_desc lbr_desc;
/* Save desired MSR intercept (read: pass-through) state */
#define MAX_POSSIBLE_PASSTHROUGH_MSRS 13
#define MAX_POSSIBLE_PASSTHROUGH_MSRS 14
struct {
DECLARE_BITMAP(read, MAX_POSSIBLE_PASSTHROUGH_MSRS);
DECLARE_BITMAP(write, MAX_POSSIBLE_PASSTHROUGH_MSRS);