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Message-ID: <0c0084cb-92c0-23fe-dc5a-441e4b04742c@intel.com>
Date: Wed, 8 Jul 2020 21:27:32 +0800
From: Xiaoyao Li <xiaoyao.li@...el.com>
To: Paolo Bonzini <pbonzini@...hat.com>,
Sean Christopherson <sean.j.christopherson@...el.com>,
Jim Mattson <jmattson@...gle.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-doc@...r.kernel.org, Jonathan Corbet <corbet@....net>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH v3 4/8] KVM: X86: Split kvm_update_cpuid()
On 7/8/2020 8:41 PM, Paolo Bonzini wrote:
> 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@...el.com>
>>>
>>> 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.
I'm ok with kvm_vcpu_after_set_cpuid().
BTW there is an unknown for me regarding enter_smm(). Currently, it
calls kvm_update_cpuid(). I'm not sure which part it really needs,
update CPUID or update vcpu state based on CPUID? maybe both?
So in this Patch, after splitting kvm_update_cpuid(), I keep both
functions there to ensure no functional change in enter_smm().
So using the name "kvm_vcpu_after_set_cpuid" seems weird in that function.
> Thanks,
>
> Paolo
>
>>> Paolo
>>>
>>>> ---
>>>> arch/x86/kvm/cpuid.c | 38 ++++++++++++++++++++++++--------------
>>>> arch/x86/kvm/cpuid.h | 1 +
>>>> arch/x86/kvm/x86.c | 1 +
>>>> 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)
>>>> void kvm_update_cpuid(struct kvm_vcpu *vcpu)
>>>> {
>>>> struct kvm_cpuid_entry2 *best;
>>>> - struct kvm_lapic *apic = vcpu->arch.apic;
>>>> best = kvm_find_cpuid_entry(vcpu, 1, 0);
>>>> if (best) {
>>>> @@ -89,26 +88,14 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu)
>>>> vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE);
>>>> }
>>>> - if (best && apic) {
>>>> - if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER))
>>>> - apic->lapic_timer.timer_mode_mask = 3 << 17;
>>>> - else
>>>> - apic->lapic_timer.timer_mode_mask = 1 << 17;
>>>> - }
>>>> -
>>>> best = kvm_find_cpuid_entry(vcpu, 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);
>>>> - if (!best) {
>>>> - vcpu->arch.guest_supported_xcr0 = 0;
>>>> - } else {
>>>> - vcpu->arch.guest_supported_xcr0 =
>>>> - (best->eax | ((u64)best->edx << 32)) & supported_xcr0;
>>>> + if (best)
>>>> best->ebx = xstate_required_size(vcpu->arch.xcr0, false);
>>>> - }
>>>> best = kvm_find_cpuid_entry(vcpu, 0xD, 1);
>>>> if (best && (cpuid_entry_has(best, X86_FEATURE_XSAVES) ||
>>>> @@ -127,6 +114,27 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu)
>>>> vcpu->arch.ia32_misc_enable_msr &
>>>> MSR_IA32_MISC_ENABLE_MWAIT);
>>>> }
>>>> +}
>>>> +
>>>> +void kvm_update_vcpu_model(struct kvm_vcpu *vcpu)
>>>> +{
>>>> + struct kvm_lapic *apic = vcpu->arch.apic;
>>>> + struct kvm_cpuid_entry2 *best;
>>>> +
>>>> + best = kvm_find_cpuid_entry(vcpu, 1, 0);
>>>> + if (best && apic) {
>>>> + if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER))
>>>> + apic->lapic_timer.timer_mode_mask = 3 << 17;
>>>> + else
>>>> + apic->lapic_timer.timer_mode_mask = 1 << 17;
>>>> + }
>>>> +
>>>> + best = kvm_find_cpuid_entry(vcpu, 0xD, 0);
>>>> + if (!best)
>>>> + vcpu->arch.guest_supported_xcr0 = 0;
>>>> + else
>>>> + vcpu->arch.guest_supported_xcr0 =
>>>> + (best->eax | ((u64)best->edx << 32)) & supported_xcr0;
>>>> /* Note, maxphyaddr must be updated before tdp_level. */
>>>> vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu);
>>>> @@ -218,6 +226,7 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
>>>> kvm_apic_set_version(vcpu);
>>>> kvm_x86_ops.cpuid_update(vcpu);
>>>> kvm_update_cpuid(vcpu);
>>>> + kvm_update_vcpu_model(vcpu);
>>>> kvfree(cpuid_entries);
>>>> out:
>>>> @@ -247,6 +256,7 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
>>>> kvm_apic_set_version(vcpu);
>>>> kvm_x86_ops.cpuid_update(vcpu);
>>>> kvm_update_cpuid(vcpu);
>>>> + kvm_update_vcpu_model(vcpu);
>>>> out:
>>>> return r;
>>>> }
>>>> 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;
>>>> void kvm_set_cpu_caps(void);
>>>> void kvm_update_cpuid(struct kvm_vcpu *vcpu);
>>>> +void kvm_update_vcpu_model(struct kvm_vcpu *vcpu);
>>>> struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
>>>> u32 function, u32 index);
>>>> 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)
>>>> #endif
>>>> kvm_update_cpuid(vcpu);
>>>> + kvm_update_vcpu_model(vcpu);
>>>> kvm_mmu_reset_context(vcpu);
>>>> }
>>>>
>>>
>>
>
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