linux-kernel - Re: [PATCH v2 08/11] KVM: x86: Pass reference pvclock as a param to kvm_setup_guest

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Message-ID: <6b2d960c-1340-4e91-ad17-0ccadd378a81@xen.org>
Date: Tue, 4 Feb 2025 09:38:11 +0000
From: Paul Durrant <xadimgnik@...il.com>
To: Sean Christopherson <seanjc@...gle.com>,
 Paolo Bonzini <pbonzini@...hat.com>, David Woodhouse <dwmw2@...radead.org>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
 syzbot+352e553a86e0d75f5120@...kaller.appspotmail.com,
 Paul Durrant <pdurrant@...zon.com>, David Woodhouse <dwmw@...zon.co.uk>,
 Vitaly Kuznetsov <vkuznets@...hat.com>
Subject: Re: [PATCH v2 08/11] KVM: x86: Pass reference pvclock as a param to
 kvm_setup_guest_pvclock()

On 04/02/2025 09:33, Paul Durrant wrote:
> On 01/02/2025 01:38, Sean Christopherson wrote:
>> Pass the reference pvclock structure that's used to setup each individual
>> pvclock as a parameter to kvm_setup_guest_pvclock() as a preparatory step
>> toward removing kvm_vcpu_arch.hv_clock.
>>
>> No functional change intended.
>>
>> Reviewed-by: Paul Durrant <paul@....org>
>> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
>> ---
>>   arch/x86/kvm/x86.c | 14 +++++++-------
>>   1 file changed, 7 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 5f3ad13a8ac7..06d27b3cc207 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -3116,17 +3116,17 @@ u64 get_kvmclock_ns(struct kvm *kvm)
>>       return data.clock;
>>   }
>> -static void kvm_setup_guest_pvclock(struct kvm_vcpu *v,
>> +static void kvm_setup_guest_pvclock(struct pvclock_vcpu_time_info 
>> *ref_hv_clock,
>> +                    struct kvm_vcpu *vcpu,
> 
> So, here 'v' becomes 'vcpu'
> 
>>                       struct gfn_to_pfn_cache *gpc,
>>                       unsigned int offset,
>>                       bool force_tsc_unstable)
>>   {
>> -    struct kvm_vcpu_arch *vcpu = &v->arch;
>>       struct pvclock_vcpu_time_info *guest_hv_clock;
>>       struct pvclock_vcpu_time_info hv_clock;
>>       unsigned long flags;
>> -    memcpy(&hv_clock, &vcpu->hv_clock, sizeof(hv_clock));
>> +    memcpy(&hv_clock, ref_hv_clock, sizeof(hv_clock));
>>       read_lock_irqsave(&gpc->lock, flags);
>>       while (!kvm_gpc_check(gpc, offset + sizeof(*guest_hv_clock))) {
>> @@ -3165,7 +3165,7 @@ static void kvm_setup_guest_pvclock(struct 
>> kvm_vcpu *v,
>>       kvm_gpc_mark_dirty_in_slot(gpc);
>>       read_unlock_irqrestore(&gpc->lock, flags);
>> -    trace_kvm_pvclock_update(v->vcpu_id, &hv_clock);
>> +    trace_kvm_pvclock_update(vcpu->vcpu_id, &hv_clock);
>>   }
>>   static int kvm_guest_time_update(struct kvm_vcpu *v)
>> @@ -3272,18 +3272,18 @@ static int kvm_guest_time_update(struct 
>> kvm_vcpu *v)
>>               vcpu->hv_clock.flags |= PVCLOCK_GUEST_STOPPED;
>>               vcpu->pvclock_set_guest_stopped_request = false;
>>           }
>> -        kvm_setup_guest_pvclock(v, &vcpu->pv_time, 0, false);
>> +        kvm_setup_guest_pvclock(&vcpu->hv_clock, v, &vcpu->pv_time, 
>> 0, false);
> 
> Yet here an below you still use 'v'. Does this actually compile?
> 

Sorry, my misreading of the patch... this is in caller context so no 
problem. The inconsistent naming was misleading me.

Reviewed-by: Paul Durrant <paul@....org>