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Re: [Qemu-arm] [PATCH V2] virtio: Fix no interrupt when not creating msi
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-arm] [PATCH V2] virtio: Fix no interrupt when not creating msi controller |
Date: |
Tue, 24 Jan 2017 10:25:00 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 |
On 23/01/2017 18:04, Michael S. Tsirkin wrote:
>> For virtio-blk, my patch moved the setting of ISR from
>> virtio_queue_guest_notifier_read to virtio_notify_irqfd. This is
>> because the irqfd emulation only needs to trigger the interrupt.
>> Setting the ISR should have been done elsewhere.
>>
>> Can vhost set ISR (I thought it couldn't)? If so, it seems like ARM was
>> relying on QEMU's irqfd emulation, as a work around for vhost not
>> setting ISR. But this only works if irqfd is directed to QEMU and not
>> to KVM. So if vhost cannot set ISR, I think vhost should be disabled
>> unless MSI is active.
>>
>> Am I missing something?
>
> vhost doesn't set ISR ATM. Without MSI we are always bouncing
> interrupts through QEMU in particular in order to set ISR.
Where is the code that disables KVM irqfd?
Paolo
> Disabling vhost when user requested it was what we did
> at some point but this just confused people.
>
>
- [Qemu-arm] [PATCH V2] virtio: Fix no interrupt when not creating msi controller, Shannon Zhao, 2017/01/22
- Re: [Qemu-arm] [PATCH V2] virtio: Fix no interrupt when not creating msi controller, Michael S. Tsirkin, 2017/01/23
- Re: [Qemu-arm] [PATCH V2] virtio: Fix no interrupt when not creating msi controller, Paolo Bonzini, 2017/01/23
- Re: [Qemu-arm] [PATCH V2] virtio: Fix no interrupt when not creating msi controller, Michael S. Tsirkin, 2017/01/23
- Re: [Qemu-arm] [PATCH V2] virtio: Fix no interrupt when not creating msi controller,
Paolo Bonzini <=
- Re: [Qemu-arm] [PATCH V2] virtio: Fix no interrupt when not creating msi controller, Michael S. Tsirkin, 2017/01/24
- Re: [Qemu-arm] [PATCH V2] virtio: Fix no interrupt when not creating msi controller, Paolo Bonzini, 2017/01/24
- Re: [Qemu-arm] [PATCH V2] virtio: Fix no interrupt when not creating msi controller, Michael S. Tsirkin, 2017/01/24
- Re: [Qemu-arm] [PATCH V2] virtio: Fix no interrupt when not creating msi controller, Paolo Bonzini, 2017/01/24
- Re: [Qemu-arm] [PATCH V2] virtio: Fix no interrupt when not creating msi controller, Michael S. Tsirkin, 2017/01/24