Commit cfc48181 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

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



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: default avatarXiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 2ef7619d

arch/x86/kvm/cpuid.c

+9 −23
Original line number Diff line number Diff line
@@ -52,16 +52,6 @@ bool kvm_mpx_supported(void) 
}

EXPORT_SYMBOL_GPL(kvm_mpx_supported);



u64 kvm_supported_xcr0(void)

{

	u64 xcr0 = KVM_SUPPORTED_XCR0 & host_xcr0;



	if (!kvm_mpx_supported())

		xcr0 &= ~(XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR);



	return xcr0;

}



#define F feature_bit



int kvm_update_cpuid(struct kvm_vcpu *vcpu)
@@ -107,8 +97,7 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu) 
		vcpu->arch.guest_xstate_size = XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET;

	} else {

		vcpu->arch.guest_supported_xcr0 =

			(best->eax | ((u64)best->edx << 32)) &

			kvm_supported_xcr0();

			(best->eax | ((u64)best->edx << 32)) & supported_xcr0;

		vcpu->arch.guest_xstate_size = best->ebx =

			xstate_required_size(vcpu->arch.xcr0, false);

	}
@@ -633,14 +622,12 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) 
				goto out;

		}

		break;

	case 0xd: {

		u64 supported = kvm_supported_xcr0();



		entry->eax &= supported;

		entry->ebx = xstate_required_size(supported, false);

	case 0xd:

		entry->eax &= supported_xcr0;

		entry->ebx = xstate_required_size(supported_xcr0, false);

		entry->ecx = entry->ebx;

		entry->edx &= supported >> 32;

		if (!supported)

		entry->edx &= supported_xcr0 >> 32;

		if (!supported_xcr0)

			break;



		entry = do_host_cpuid(array, function, 1);
@@ -650,7 +637,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) 
		entry->eax &= kvm_cpuid_D_1_eax_x86_features;

		cpuid_mask(&entry->eax, CPUID_D_1_EAX);

		if (entry->eax & (F(XSAVES)|F(XSAVEC)))

			entry->ebx = xstate_required_size(supported, true);

			entry->ebx = xstate_required_size(supported_xcr0, true);

		else

			entry->ebx = 0;

		/* Saving XSS controlled state via XSAVES isn't supported. */
@@ -658,7 +645,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) 
		entry->edx = 0;



		for (i = 2; i < 64; ++i) {

			if (!(supported & BIT_ULL(i)))

			if (!(supported_xcr0 & BIT_ULL(i)))

				continue;



			entry = do_host_cpuid(array, function, i);
@@ -666,7 +653,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) 
				goto out;



			/*

			 * The @supported check above should have filtered out

			 * The supported check above should have filtered out

			 * invalid sub-leafs as well as sub-leafs managed by

			 * IA32_XSS MSR.  Only XCR0-managed sub-leafs should

			 * reach this point, and they should have a non-zero
@@ -681,7 +668,6 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) 
			entry->edx = 0;

		}

		break;

	}

	/* Intel PT */

	case 0x14:

		if (!f_intel_pt)

arch/x86/kvm/svm.c

+2 −0
Original line number Diff line number Diff line
@@ -1385,6 +1385,8 @@ static __init int svm_hardware_setup(void) 


	init_msrpm_offsets();



	supported_xcr0 &= ~(XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR);



	if (boot_cpu_has(X86_FEATURE_NX))

		kvm_enable_efer_bits(EFER_NX);

arch/x86/kvm/vmx/vmx.c

+4 −0
Original line number Diff line number Diff line
@@ -7660,6 +7660,10 @@ static __init int hardware_setup(void) 
		WARN_ONCE(host_bndcfgs, "KVM: BNDCFGS in host will be lost");

	}



	if (!kvm_mpx_supported())

		supported_xcr0 &= ~(XFEATURE_MASK_BNDREGS |

				    XFEATURE_MASK_BNDCSR);



	if (!cpu_has_vmx_vpid() || !cpu_has_vmx_invvpid() ||

	    !(cpu_has_vmx_invvpid_single() || cpu_has_vmx_invvpid_global()))

		enable_vpid = 0;

arch/x86/kvm/x86.c

+11 −3
Original line number Diff line number Diff line
@@ -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)

arch/x86/kvm/x86.h

+1 −6
Original line number Diff line number Diff line
@@ -270,13 +270,8 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, 
			    int emulation_type, void *insn, int insn_len);

enum exit_fastpath_completion handle_fastpath_set_msr_irqoff(struct kvm_vcpu *vcpu);



#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)

extern u64 host_xcr0;



extern u64 kvm_supported_xcr0(void);

extern u64 supported_xcr0;



extern unsigned int min_timer_period_us;

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