Commit 61f20813 authored by Jing Liu's avatar Jing Liu Committed by Paolo Bonzini
Browse files

kvm: x86: Disable RDMSR interception of IA32_XFD_ERR 



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: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarJing Liu <jing2.liu@intel.com>
Signed-off-by: default avatarYang Zhong <yang.zhong@intel.com>
Message-Id: <20220105123532.12586-15-yang.zhong@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 548e8365

arch/x86/kvm/vmx/vmx.c

+6 −0
Original line number Diff line number Diff line
@@ -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);

arch/x86/kvm/vmx/vmx.h

+1 −1
Original line number Diff line number Diff line
@@ -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);