Re: [RFC PATCH 23/27] vhost: unmap qemu's shadow virtqueues on sw live migration

From: Stefano Garzarella <sgarzare@redhat.com>
To: "Eugenio Pérez" <eperezma@redhat.com>
Cc: kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
	qemu-devel@nongnu.org, Daniel Daly <dandaly0@gmail.com>,
	virtualization@lists.linux-foundation.org,
	Liran Alon <liralon@gmail.com>, Eli Cohen <eli@mellanox.com>,
	Nitin Shrivastav <nitin.shrivastav@broadcom.com>,
	Alex Barba <alex.barba@broadcom.com>,
	Christophe Fontaine <cfontain@redhat.com>,
	Lee Ballard <ballle98@gmail.com>,
	Lars Ganrot <lars.ganrot@gmail.com>,
	Rob Miller <rob.miller@broadcom.com>,
	Howard Cai <howard.cai@gmail.com>,
	Parav Pandit <parav@mellanox.com>, vm <vmireyno@marvell.com>,
	Salil Mehta <mehta.salil.lnk@gmail.com>,
	Stephen Finucane <stephenfin@redhat.com>,
	Xiao W Wang <xiao.w.wang@intel.com>,
	Sean Mooney <smooney@redhat.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Jim Harford <jim.harford@broadcom.com>,
	Dmytro Kazantsev <dmytro.kazantsev@gmail.com>,
	Siwei Liu <loseweigh@gmail.com>,
	Harpreet Singh Anand <hanand@xilinx.com>,
	Michael Lilja <ml@napatech.com>, Max Gurtovoy <maxgu14@gmail.com>
Subject: Re: [RFC PATCH 23/27] vhost: unmap qemu's shadow virtqueues on sw live migration
Date: Fri, 27 Nov 2020 16:29:01 +0100	[thread overview]
Message-ID: <20201127152901.cbfu7rmewbxventr@steredhat> (raw)
In-Reply-To: <20201120185105.279030-24-eperezma@redhat.com>

On Fri, Nov 20, 2020 at 07:51:01PM +0100, Eugenio PÃ©rez wrote:
>Since vhost does not need to access it, it has no sense to keep it
>mapped.
>
>Signed-off-by: Eugenio PÃ©rez <eperezma@redhat.com>
>---
> hw/virtio/vhost.c | 1 +
> 1 file changed, 1 insertion(+)
>
>diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
>index f640d4edf0..eebfac4455 100644
>--- a/hw/virtio/vhost.c
>+++ b/hw/virtio/vhost.c
>@@ -1124,6 +1124,7 @@ static int vhost_sw_live_migration_start(struct vhost_dev *dev)
>
>         dev->sw_lm_shadow_vq[idx] = vhost_sw_lm_shadow_vq(dev, idx);
>         event_notifier_set_handler(&vq->masked_notifier, vhost_handle_call);
>+        vhost_virtqueue_memory_unmap(dev, &dev->vqs[idx], true);

IIUC vhost_virtqueue_memory_unmap() is already called at the end of 
vhost_virtqueue_stop(), so we can skip this call, right?

>
>         vhost_vring_write_addr(dev->sw_lm_shadow_vq[idx], &addr);
>         r = dev->vhost_ops->vhost_set_vring_addr(dev, &addr);
>-- 2.18.4
>

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