Re: [PATCH v3 4/8] KVM: X86: Split kvm_update_cpuid()

[Paolo Bonzini]

On 08/07/20 14:33, Xiaoyao Li wrote:
> On 7/8/2020 8:06 PM, Paolo Bonzini wrote:
>> On 08/07/20 08:50, Xiaoyao Li wrote:
>>> Split the part of updating vcpu model out of kvm_update_cpuid(), and put
>>> it into a new kvm_update_vcpu_model(). So it's more clear that
>>> kvm_update_cpuid() is to update guest CPUID settings, while
>>> kvm_update_vcpu_model() is to update vcpu model (settings) based on the
>>> updated CPUID settings.
>>>
>>> Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
>>
>> I would prefer to keep the kvm_update_cpuid name for what you called
>> kvm_update_vcpu_model(), and rename the rest to
>> kvm_update_cpuid_runtime().
> 
> But there is no CPUID being updated in kvm_update_cpuid(), after
> kvm_update_cpuid_runtime() is split out. This is confusing, IMO.

Then what about kvm_vcpu_after_set_cpuid()?  It's the "model" that is
not clear.

Thanks,

Paolo

>> Paolo
>>
>>> ---
>>> Â arch/x86/kvm/cpuid.c | 38 ++++++++++++++++++++++++--------------
>>> Â arch/x86/kvm/cpuid.h |Â 1 +
>>> Â arch/x86/kvm/x86.cÂÂ |Â 1 +
>>> Â 3 files changed, 26 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
>>> index a825878b7f84..001f5a94880e 100644
>>> --- a/arch/x86/kvm/cpuid.c
>>> +++ b/arch/x86/kvm/cpuid.c
>>> @@ -76,7 +76,6 @@ static int kvm_check_cpuid(struct kvm_vcpu *vcpu)
>>> Â void kvm_update_cpuid(struct kvm_vcpu *vcpu)
>>> Â {
>>> ÂÂÂÂÂ struct kvm_cpuid_entry2 *best;
>>> -ÂÂÂ struct kvm_lapic *apic = vcpu->arch.apic;
>>> Â ÂÂÂÂÂ best = kvm_find_cpuid_entry(vcpu, 1, 0);
>>> ÂÂÂÂÂ if (best) {
>>> @@ -89,26 +88,14 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu)
>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE);
>>> ÂÂÂÂÂ }
>>> Â -ÂÂÂ if (best && apic) {
>>> -ÂÂÂÂÂÂÂ if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER))
>>> -ÂÂÂÂÂÂÂÂÂÂÂ apic->lapic_timer.timer_mode_mask = 3 << 17;
>>> -ÂÂÂÂÂÂÂ else
>>> -ÂÂÂÂÂÂÂÂÂÂÂ apic->lapic_timer.timer_mode_mask = 1 << 17;
>>> -ÂÂÂ }
>>> -
>>> ÂÂÂÂÂ best = kvm_find_cpuid_entry(vcpu, 7, 0);
>>> ÂÂÂÂÂ if (best && boot_cpu_has(X86_FEATURE_PKU) && best->function ==
>>> 0x7)
>>> ÂÂÂÂÂÂÂÂÂ cpuid_entry_change(best, X86_FEATURE_OSPKE,
>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ kvm_read_cr4_bits(vcpu, X86_CR4_PKE));
>>> Â ÂÂÂÂÂ best = kvm_find_cpuid_entry(vcpu, 0xD, 0);
>>> -ÂÂÂ if (!best) {
>>> -ÂÂÂÂÂÂÂ vcpu->arch.guest_supported_xcr0 = 0;
>>> -ÂÂÂ } else {
>>> -ÂÂÂÂÂÂÂ vcpu->arch.guest_supported_xcr0 =
>>> -ÂÂÂÂÂÂÂÂÂÂÂ (best->eax | ((u64)best->edx << 32)) & supported_xcr0;
>>> +ÂÂÂ if (best)
>>> ÂÂÂÂÂÂÂÂÂ best->ebx = xstate_required_size(vcpu->arch.xcr0, false);
>>> -ÂÂÂ }
>>> Â ÂÂÂÂÂ best = kvm_find_cpuid_entry(vcpu, 0xD, 1);
>>> ÂÂÂÂÂ if (best && (cpuid_entry_has(best, X86_FEATURE_XSAVES) ||
>>> @@ -127,6 +114,27 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu)
>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ vcpu->arch.ia32_misc_enable_msr &
>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ MSR_IA32_MISC_ENABLE_MWAIT);
>>> ÂÂÂÂÂ }
>>> +}
>>> +
>>> +void kvm_update_vcpu_model(struct kvm_vcpu *vcpu)
>>> +{
>>> +ÂÂÂ struct kvm_lapic *apic = vcpu->arch.apic;
>>> +ÂÂÂ struct kvm_cpuid_entry2 *best;
>>> +
>>> +ÂÂÂ best = kvm_find_cpuid_entry(vcpu, 1, 0);
>>> +ÂÂÂ if (best && apic) {
>>> +ÂÂÂÂÂÂÂ if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER))
>>> +ÂÂÂÂÂÂÂÂÂÂÂ apic->lapic_timer.timer_mode_mask = 3 << 17;
>>> +ÂÂÂÂÂÂÂ else
>>> +ÂÂÂÂÂÂÂÂÂÂÂ apic->lapic_timer.timer_mode_mask = 1 << 17;
>>> +ÂÂÂ }
>>> +
>>> +ÂÂÂ best = kvm_find_cpuid_entry(vcpu, 0xD, 0);
>>> +ÂÂÂ if (!best)
>>> +ÂÂÂÂÂÂÂ vcpu->arch.guest_supported_xcr0 = 0;
>>> +ÂÂÂ else
>>> +ÂÂÂÂÂÂÂ vcpu->arch.guest_supported_xcr0 =
>>> +ÂÂÂÂÂÂÂÂÂÂÂ (best->eax | ((u64)best->edx << 32)) & supported_xcr0;
>>> Â ÂÂÂÂÂ /* Note, maxphyaddr must be updated before tdp_level. */
>>> ÂÂÂÂÂ vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu);
>>> @@ -218,6 +226,7 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
>>> ÂÂÂÂÂ kvm_apic_set_version(vcpu);
>>> ÂÂÂÂÂ kvm_x86_ops.cpuid_update(vcpu);
>>> ÂÂÂÂÂ kvm_update_cpuid(vcpu);
>>> +ÂÂÂ kvm_update_vcpu_model(vcpu);
>>> Â ÂÂÂÂÂ kvfree(cpuid_entries);
>>> Â out:
>>> @@ -247,6 +256,7 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
>>> ÂÂÂÂÂ kvm_apic_set_version(vcpu);
>>> ÂÂÂÂÂ kvm_x86_ops.cpuid_update(vcpu);
>>> ÂÂÂÂÂ kvm_update_cpuid(vcpu);
>>> +ÂÂÂ kvm_update_vcpu_model(vcpu);
>>> Â out:
>>> ÂÂÂÂÂ return r;
>>> Â }
>>> diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
>>> index f136de1debad..45e3643e2fba 100644
>>> --- a/arch/x86/kvm/cpuid.h
>>> +++ b/arch/x86/kvm/cpuid.h
>>> @@ -10,6 +10,7 @@ extern u32 kvm_cpu_caps[NCAPINTS] __read_mostly;
>>> Â void kvm_set_cpu_caps(void);
>>> Â Â void kvm_update_cpuid(struct kvm_vcpu *vcpu);
>>> +void kvm_update_vcpu_model(struct kvm_vcpu *vcpu);
>>> Â struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ u32 function, u32 index);
>>> Â int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,
>>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>>> index 09ee54f5e385..6f376392e6e6 100644
>>> --- a/arch/x86/kvm/x86.c
>>> +++ b/arch/x86/kvm/x86.c
>>> @@ -8184,6 +8184,7 @@ static void enter_smm(struct kvm_vcpu *vcpu)
>>> Â #endif
>>> Â ÂÂÂÂÂ kvm_update_cpuid(vcpu);
>>> +ÂÂÂ kvm_update_vcpu_model(vcpu);
>>> ÂÂÂÂÂ kvm_mmu_reset_context(vcpu);
>>> Â }
>>> Â
>>
>