Re: [PATCH v2 30/49] KVM: x86: Always operate on kvm_vcpu data in cpuid_entry2_find()

[Maxim Levitsky <mlevitsk@redhat.com>]

On Fri, 2024-05-17 at 10:39 -0700, Sean Christopherson wrote:
> Now that KVM sets vcpu->arch.cpuid_{entries,nent} before processing the
> incoming CPUID entries during KVM_SET_CPUID{,2}, drop the @entries and
> @nent params from cpuid_entry2_find() and unconditionally operate on the
> vCPU state.
> 
> No functional change intended.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>  arch/x86/kvm/cpuid.c | 62 +++++++++++++++-----------------------------
>  1 file changed, 21 insertions(+), 41 deletions(-)
> 
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 7290f91c422c..0526f25a7c80 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -124,8 +124,8 @@ u32 xstate_required_size(u64 xstate_bv, bool compacted)
>   */
>  #define KVM_CPUID_INDEX_NOT_SIGNIFICANT -1ull
>  
> -static inline struct kvm_cpuid_entry2 *cpuid_entry2_find(
> -	struct kvm_cpuid_entry2 *entries, int nent, u32 function, u64 index)
> +static struct kvm_cpuid_entry2 *cpuid_entry2_find(struct kvm_vcpu *vcpu,
> +						  u32 function, u64 index)
>  {
>  	struct kvm_cpuid_entry2 *e;
>  	int i;
> @@ -142,8 +142,8 @@ static inline struct kvm_cpuid_entry2 *cpuid_entry2_find(
>  	 */
>  	lockdep_assert_irqs_enabled();
>  
> -	for (i = 0; i < nent; i++) {
> -		e = &entries[i];
> +	for (i = 0; i < vcpu->arch.cpuid_nent; i++) {
> +		e = &vcpu->arch.cpuid_entries[i];
>  
>  		if (e->function != function)
>  			continue;
> @@ -177,8 +177,6 @@ static inline struct kvm_cpuid_entry2 *cpuid_entry2_find(
>  
>  static int kvm_check_cpuid(struct kvm_vcpu *vcpu)
>  {
> -	struct kvm_cpuid_entry2 *entries = vcpu->arch.cpuid_entries;
> -	int nent = vcpu->arch.cpuid_nent;
>  	struct kvm_cpuid_entry2 *best;
>  	u64 xfeatures;
>  
> @@ -186,7 +184,7 @@ static int kvm_check_cpuid(struct kvm_vcpu *vcpu)
>  	 * The existing code assumes virtual address is 48-bit or 57-bit in the
>  	 * canonical address checks; exit if it is ever changed.
>  	 */
> -	best = cpuid_entry2_find(entries, nent, 0x80000008,
> +	best = cpuid_entry2_find(vcpu, 0x80000008,
>  				 KVM_CPUID_INDEX_NOT_SIGNIFICANT);
>  	if (best) {
>  		int vaddr_bits = (best->eax & 0xff00) >> 8;
> @@ -199,7 +197,7 @@ static int kvm_check_cpuid(struct kvm_vcpu *vcpu)
>  	 * Exposing dynamic xfeatures to the guest requires additional
>  	 * enabling in the FPU, e.g. to expand the guest XSAVE state size.
>  	 */
> -	best = cpuid_entry2_find(entries, nent, 0xd, 0);
> +	best = cpuid_entry2_find(vcpu, 0xd, 0);
>  	if (!best)
>  		return 0;
>  
> @@ -234,15 +232,15 @@ static int kvm_cpuid_check_equal(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2
>  	return 0;
>  }
>  
> -static struct kvm_hypervisor_cpuid __kvm_get_hypervisor_cpuid(struct kvm_cpuid_entry2 *entries,
> -							      int nent, const char *sig)
> +static struct kvm_hypervisor_cpuid kvm_get_hypervisor_cpuid(struct kvm_vcpu *vcpu,
> +							    const char *sig)
>  {
>  	struct kvm_hypervisor_cpuid cpuid = {};
>  	struct kvm_cpuid_entry2 *entry;
>  	u32 base;
>  
>  	for_each_possible_hypervisor_cpuid_base(base) {
> -		entry = cpuid_entry2_find(entries, nent, base, KVM_CPUID_INDEX_NOT_SIGNIFICANT);
> +		entry = cpuid_entry2_find(vcpu, base, KVM_CPUID_INDEX_NOT_SIGNIFICANT);
>  
>  		if (entry) {
>  			u32 signature[3];
> @@ -262,13 +260,6 @@ static struct kvm_hypervisor_cpuid __kvm_get_hypervisor_cpuid(struct kvm_cpuid_e
>  	return cpuid;
>  }
>  
> -static struct kvm_hypervisor_cpuid kvm_get_hypervisor_cpuid(struct kvm_vcpu *vcpu,
> -							    const char *sig)
> -{
> -	return __kvm_get_hypervisor_cpuid(vcpu->arch.cpuid_entries,
> -					  vcpu->arch.cpuid_nent, sig);
> -}
> -
>  static u32 kvm_apply_cpuid_pv_features_quirk(struct kvm_vcpu *vcpu)
>  {
>  	struct kvm_hypervisor_cpuid kvm_cpuid;
> @@ -292,23 +283,22 @@ static u32 kvm_apply_cpuid_pv_features_quirk(struct kvm_vcpu *vcpu)
>   * Calculate guest's supported XCR0 taking into account guest CPUID data and
>   * KVM's supported XCR0 (comprised of host's XCR0 and KVM_SUPPORTED_XCR0).
>   */
> -static u64 cpuid_get_supported_xcr0(struct kvm_cpuid_entry2 *entries, int nent)
> +static u64 cpuid_get_supported_xcr0(struct kvm_vcpu *vcpu)
>  {
>  	struct kvm_cpuid_entry2 *best;
>  
> -	best = cpuid_entry2_find(entries, nent, 0xd, 0);
> +	best = cpuid_entry2_find(vcpu, 0xd, 0);
>  	if (!best)
>  		return 0;
>  
>  	return (best->eax | ((u64)best->edx << 32)) & kvm_caps.supported_xcr0;
>  }
>  
> -static void __kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *entries,
> -				       int nent)
> +void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
>  {
>  	struct kvm_cpuid_entry2 *best;
>  
> -	best = cpuid_entry2_find(entries, nent, 1, KVM_CPUID_INDEX_NOT_SIGNIFICANT);
> +	best = cpuid_entry2_find(vcpu, 1, KVM_CPUID_INDEX_NOT_SIGNIFICANT);
>  	if (best) {
>  		/* Update OSXSAVE bit */
>  		if (boot_cpu_has(X86_FEATURE_XSAVE))
> @@ -319,43 +309,36 @@ static void __kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu, struct kvm_cpuid_e
>  			   vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE);
>  	}
>  
> -	best = cpuid_entry2_find(entries, nent, 7, 0);
> +	best = cpuid_entry2_find(vcpu, 7, 0);
>  	if (best && boot_cpu_has(X86_FEATURE_PKU) && best->function == 0x7)
>  		cpuid_entry_change(best, X86_FEATURE_OSPKE,
>  				   kvm_is_cr4_bit_set(vcpu, X86_CR4_PKE));
>  
> -	best = cpuid_entry2_find(entries, nent, 0xD, 0);
> +	best = cpuid_entry2_find(vcpu, 0xD, 0);
>  	if (best)
>  		best->ebx = xstate_required_size(vcpu->arch.xcr0, false);
>  
> -	best = cpuid_entry2_find(entries, nent, 0xD, 1);
> +	best = cpuid_entry2_find(vcpu, 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);
>  
>  	if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT)) {
> -		best = cpuid_entry2_find(entries, nent, 0x1, KVM_CPUID_INDEX_NOT_SIGNIFICANT);
> +		best = cpuid_entry2_find(vcpu, 0x1, KVM_CPUID_INDEX_NOT_SIGNIFICANT);
>  		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 bool kvm_cpuid_has_hyperv(struct kvm_vcpu *vcpu)
>  {
>  #ifdef CONFIG_KVM_HYPERV
> -	struct kvm_cpuid_entry2 *entries = vcpu->arch.cpuid_entries;
> -	int nent = vcpu->arch.cpuid_nent;
>  	struct kvm_cpuid_entry2 *entry;
>  
> -	entry = cpuid_entry2_find(entries, nent, HYPERV_CPUID_INTERFACE,
> +	entry = cpuid_entry2_find(vcpu, HYPERV_CPUID_INTERFACE,
>  				  KVM_CPUID_INDEX_NOT_SIGNIFICANT);
>  	return entry && entry->eax == HYPERV_CPUID_SIGNATURE_EAX;
>  #else
> @@ -401,8 +384,7 @@ void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
>  		kvm_apic_set_version(vcpu);
>  	}
>  
> -	vcpu->arch.guest_supported_xcr0 =
> -		cpuid_get_supported_xcr0(vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent);
> +	vcpu->arch.guest_supported_xcr0 = cpuid_get_supported_xcr0(vcpu);
>  
>  	vcpu->arch.pv_cpuid.features = kvm_apply_cpuid_pv_features_quirk(vcpu);
>  
> @@ -1532,16 +1514,14 @@ int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,
>  struct kvm_cpuid_entry2 *kvm_find_cpuid_entry_index(struct kvm_vcpu *vcpu,
>  						    u32 function, u32 index)
>  {
> -	return cpuid_entry2_find(vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent,
> -				 function, index);
> +	return cpuid_entry2_find(vcpu, function, index);
>  }
>  EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry_index);
>  
>  struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
>  					      u32 function)
>  {
> -	return cpuid_entry2_find(vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent,
> -				 function, KVM_CPUID_INDEX_NOT_SIGNIFICANT);
> +	return cpuid_entry2_find(vcpu, function, KVM_CPUID_INDEX_NOT_SIGNIFICANT);
>  }
>  EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry);
>  

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>

Best regards,
	Maxim Levitsky