Re: [PATCH] KVM: avoid warning on s390 in mark_page_dirty

[Christian Borntraeger <borntraeger@linux.ibm.com>]

Am 18.01.22 um 09:44 schrieb Paolo Bonzini:
> On 1/18/22 09:37, Christian Borntraeger wrote:
>> Am 13.01.22 um 13:29 schrieb Christian Borntraeger:
>>> Avoid warnings on s390 like
>>> [ 1801.980931] CPU: 12 PID: 117600 Comm: kworker/12:0 Tainted: G            E 5.17.0-20220113.rc0.git0.32ce2abb03cf.300.fc35.s390x+next #1
>>> [ 1801.980938] Workqueue: events irqfd_inject [kvm]
>>> [...]
>>> [ 1801.981057] Call Trace:
>>> [ 1801.981060]  [<000003ff805f0f5c>] mark_page_dirty_in_slot+0xa4/0xb0 [kvm]
>>> [ 1801.981083]  [<000003ff8060e9fe>] adapter_indicators_set+0xde/0x268 [kvm]
>>> [ 1801.981104]  [<000003ff80613c24>] set_adapter_int+0x64/0xd8 [kvm]
>>> [ 1801.981124]  [<000003ff805fb9aa>] kvm_set_irq+0xc2/0x130 [kvm]
>>> [ 1801.981144]  [<000003ff805f8d86>] irqfd_inject+0x76/0xa0 [kvm]
>>> [ 1801.981164]  [<0000000175e56906>] process_one_work+0x1fe/0x470
>>> [ 1801.981173]  [<0000000175e570a4>] worker_thread+0x64/0x498
>>> [ 1801.981176]  [<0000000175e5ef2c>] kthread+0x10c/0x110
>>> [ 1801.981180]  [<0000000175de73c8>] __ret_from_fork+0x40/0x58
>>> [ 1801.981185]  [<000000017698440a>] ret_from_fork+0xa/0x40
>>>
>>> when writing to a guest from an irqfd worker as long as we do not have
>>> the dirty ring.
>>>
>>> Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
>>> ---
>>>   virt/kvm/kvm_main.c | 2 ++
>>>   1 file changed, 2 insertions(+)
>>>
>>> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
>>> index 504158f0e131..1a682d3e106d 100644
>>> --- a/virt/kvm/kvm_main.c
>>> +++ b/virt/kvm/kvm_main.c
>>> @@ -3163,8 +3163,10 @@ void mark_page_dirty_in_slot(struct kvm *kvm,
>>>   {
>>>       struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
>>> +#ifdef CONFIG_HAVE_KVM_DIRTY_RING
>>>       if (WARN_ON_ONCE(!vcpu) || WARN_ON_ONCE(vcpu->kvm != kvm))
>>>           return;
>>> +#endif
>>>       if (memslot && kvm_slot_dirty_track_enabled(memslot)) {
>>>           unsigned long rel_gfn = gfn - memslot->base_gfn;
>>
>> Paolo, are you going to pick this for next for the time being?
>>
> 
> Yep, done now.
> 
> Paolo

Thanks. I just realized that Davids patch meanwhile landed in Linus tree. So better
take this via master and not next.
Maybe also add
Fixes: 2efd61a608b0 ("KVM: Warn if mark_page_dirty() is called without an active vCPU")
in case the patch is picked for stable