Commit ee3a5f9e authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Paolo Bonzini
Browse files

KVM: x86: Do runtime CPUID update before updating vcpu->arch.cpuid_entries 



kvm_update_cpuid_runtime() mangles CPUID data coming from userspace
VMM after updating 'vcpu->arch.cpuid_entries', this makes it
impossible to compare an update with what was previously
supplied. Introduce __kvm_update_cpuid_runtime() version which can be
used to tweak the input before it goes to 'vcpu->arch.cpuid_entries'
so the upcoming update check can compare tweaked data.

No functional change intended.

Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220117150542.2176196-2-vkuznets@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent a2186448

arch/x86/kvm/cpuid.c

+24 −10
Original line number Diff line number Diff line
@@ -145,14 +145,21 @@ static void kvm_update_kvm_cpuid_base(struct kvm_vcpu *vcpu) 
	}

}



static struct kvm_cpuid_entry2 *kvm_find_kvm_cpuid_features(struct kvm_vcpu *vcpu)

static struct kvm_cpuid_entry2 *__kvm_find_kvm_cpuid_features(struct kvm_vcpu *vcpu,

					      struct kvm_cpuid_entry2 *entries, int nent)

{

	u32 base = vcpu->arch.kvm_cpuid_base;



	if (!base)

		return NULL;



	return kvm_find_cpuid_entry(vcpu, base | KVM_CPUID_FEATURES, 0);

	return cpuid_entry2_find(entries, nent, base | KVM_CPUID_FEATURES, 0);

}



static struct kvm_cpuid_entry2 *kvm_find_kvm_cpuid_features(struct kvm_vcpu *vcpu)

{

	return __kvm_find_kvm_cpuid_features(vcpu, vcpu->arch.cpuid_entries,

					     vcpu->arch.cpuid_nent);

}



void kvm_update_pv_runtime(struct kvm_vcpu *vcpu)
@@ -167,11 +174,12 @@ void kvm_update_pv_runtime(struct kvm_vcpu *vcpu) 
		vcpu->arch.pv_cpuid.features = best->eax;

}



void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)

static void __kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *entries,

				       int nent)

{

	struct kvm_cpuid_entry2 *best;



	best = kvm_find_cpuid_entry(vcpu, 1, 0);

	best = cpuid_entry2_find(entries, nent, 1, 0);

	if (best) {

		/* Update OSXSAVE bit */

		if (boot_cpu_has(X86_FEATURE_XSAVE))
@@ -182,33 +190,38 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu) 
			   vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE);

	}



	best = kvm_find_cpuid_entry(vcpu, 7, 0);

	best = cpuid_entry2_find(entries, nent, 7, 0);

	if (best && boot_cpu_has(X86_FEATURE_PKU) && best->function == 0x7)

		cpuid_entry_change(best, X86_FEATURE_OSPKE,

				   kvm_read_cr4_bits(vcpu, X86_CR4_PKE));



	best = kvm_find_cpuid_entry(vcpu, 0xD, 0);

	best = cpuid_entry2_find(entries, nent, 0xD, 0);

	if (best)

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



	best = kvm_find_cpuid_entry(vcpu, 0xD, 1);

	best = cpuid_entry2_find(entries, nent, 0xD, 1);

	if (best && (cpuid_entry_has(best, X86_FEATURE_XSAVES) ||

		     cpuid_entry_has(best, X86_FEATURE_XSAVEC)))

		best->ebx = xstate_required_size(vcpu->arch.xcr0, true);



	best = kvm_find_kvm_cpuid_features(vcpu);

	best = __kvm_find_kvm_cpuid_features(vcpu, entries, nent);

	if (kvm_hlt_in_guest(vcpu->kvm) && best &&

		(best->eax & (1 << KVM_FEATURE_PV_UNHALT)))

		best->eax &= ~(1 << KVM_FEATURE_PV_UNHALT);



	if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT)) {

		best = kvm_find_cpuid_entry(vcpu, 0x1, 0);

		best = cpuid_entry2_find(entries, nent, 0x1, 0);

		if (best)

			cpuid_entry_change(best, X86_FEATURE_MWAIT,

					   vcpu->arch.ia32_misc_enable_msr &

					   MSR_IA32_MISC_ENABLE_MWAIT);

	}

}



void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)

{

	__kvm_update_cpuid_runtime(vcpu, vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent);

}

EXPORT_SYMBOL_GPL(kvm_update_cpuid_runtime);



static void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
@@ -298,6 +311,8 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2, 
{

	int r;



	__kvm_update_cpuid_runtime(vcpu, e2, nent);



	r = kvm_check_cpuid(vcpu, e2, nent);

	if (r)

		return r;
@@ -307,7 +322,6 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2, 
	vcpu->arch.cpuid_nent = nent;



	kvm_update_kvm_cpuid_base(vcpu);

	kvm_update_cpuid_runtime(vcpu);

	kvm_vcpu_after_set_cpuid(vcpu);



	return 0;