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Date:   Tue, 18 Jan 2022 09:37:45 +0100
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Subject: Re: [PATCH] KVM: avoid warning on s390 in mark_page_dirty
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To:     dwmw2@infradead.org, pbonzini@redhat.com
Cc:     butterflyhuangxx@gmail.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, seanjc@google.com,
        Cornelia Huck <cohuck@redhat.com>,
        Janosch Frank <frankja@linux.ibm.com>,
        David Hildenbrand <david@redhat.com>,
        linux-s390 <linux-s390@vger.kernel.org>,
        Thomas Huth <thuth@redhat.com>,
        Claudio Imbrenda <imbrenda@linux.ibm.com>
References: <e9e5521d-21e5-8f6f-902c-17b0516b9839@redhat.com>
 <20220113122924.740496-1-borntraeger@linux.ibm.com>
From:   Christian Borntraeger <borntraeger@linux.ibm.com>
In-Reply-To: <20220113122924.740496-1-borntraeger@linux.ibm.com>
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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?