Commit 10d7bf1e authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Paolo Bonzini
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KVM: x86: hyper-v: Cache guest CPUID leaves determining features availability 



Limiting exposed Hyper-V features requires a fast way to check if the
particular feature is exposed in guest visible CPUIDs or not. To aboid
looping through all CPUID entries on every hypercall/MSR access cache
the required leaves on CPUID update.

Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-4-vkuznets@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 644f7067

arch/x86/include/asm/kvm_host.h

+8 −0
Original line number Diff line number Diff line
@@ -544,6 +544,14 @@ struct kvm_vcpu_hv { 
	DECLARE_BITMAP(stimer_pending_bitmap, HV_SYNIC_STIMER_COUNT);

	cpumask_t tlb_flush;

	bool enforce_cpuid;

	struct {

		u32 features_eax; /* HYPERV_CPUID_FEATURES.EAX */

		u32 features_ebx; /* HYPERV_CPUID_FEATURES.EBX */

		u32 features_edx; /* HYPERV_CPUID_FEATURES.EDX */

		u32 enlightenments_eax; /* HYPERV_CPUID_ENLIGHTMENT_INFO.EAX */

		u32 enlightenments_ebx; /* HYPERV_CPUID_ENLIGHTMENT_INFO.EBX */

		u32 syndbg_cap_eax; /* HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES.EAX */

	} cpuid_cache;

};



/* Xen HVM per vcpu emulation context */

arch/x86/kvm/hyperv.c

+39 −10
Original line number Diff line number Diff line
@@ -274,15 +274,10 @@ static int synic_set_msr(struct kvm_vcpu_hv_synic *synic, 


static bool kvm_hv_is_syndbg_enabled(struct kvm_vcpu *vcpu)

{

	struct kvm_cpuid_entry2 *entry;



	entry = kvm_find_cpuid_entry(vcpu,

				     HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES,

				     0);

	if (!entry)

		return false;

	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);



	return entry->eax & HV_X64_SYNDBG_CAP_ALLOW_KERNEL_DEBUGGING;

	return hv_vcpu->cpuid_cache.syndbg_cap_eax &

		HV_X64_SYNDBG_CAP_ALLOW_KERNEL_DEBUGGING;

}



static int kvm_hv_syndbg_complete_userspace(struct kvm_vcpu *vcpu)
@@ -1845,12 +1840,46 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool 
void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu)

{

	struct kvm_cpuid_entry2 *entry;

	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);



	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_INTERFACE, 0);

	if (entry && entry->eax == HYPERV_CPUID_SIGNATURE_EAX)

	if (entry && entry->eax == HYPERV_CPUID_SIGNATURE_EAX) {

		vcpu->arch.hyperv_enabled = true;

	else

	} else {

		vcpu->arch.hyperv_enabled = false;

		return;

	}



	if (!to_hv_vcpu(vcpu) && kvm_hv_vcpu_init(vcpu))

		return;



	hv_vcpu = to_hv_vcpu(vcpu);



	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_FEATURES, 0);

	if (entry) {

		hv_vcpu->cpuid_cache.features_eax = entry->eax;

		hv_vcpu->cpuid_cache.features_ebx = entry->ebx;

		hv_vcpu->cpuid_cache.features_edx = entry->edx;

	} else {

		hv_vcpu->cpuid_cache.features_eax = 0;

		hv_vcpu->cpuid_cache.features_ebx = 0;

		hv_vcpu->cpuid_cache.features_edx = 0;

	}



	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_ENLIGHTMENT_INFO, 0);

	if (entry) {

		hv_vcpu->cpuid_cache.enlightenments_eax = entry->eax;

		hv_vcpu->cpuid_cache.enlightenments_ebx = entry->ebx;

	} else {

		hv_vcpu->cpuid_cache.enlightenments_eax = 0;

		hv_vcpu->cpuid_cache.enlightenments_ebx = 0;

	}



	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES, 0);

	if (entry)

		hv_vcpu->cpuid_cache.syndbg_cap_eax = entry->eax;

	else

		hv_vcpu->cpuid_cache.syndbg_cap_eax = 0;

}



int kvm_hv_set_enforce_cpuid(struct kvm_vcpu *vcpu, bool enforce)