* [PATCH] virtio: remove virtio_tswap16s() call in vring_packed_event_read()
@ 2024-07-01 7:52 Stefano Garzarella
2024-07-01 8:22 ` Jason Wang
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Stefano Garzarella @ 2024-07-01 7:52 UTC (permalink / raw)
To: qemu-devel
Cc: Eugenio Perez Martin, jasowang, Peter Maydell, Michael S. Tsirkin,
qemu-stable, Stefano Garzarella, Xoykie
Commit d152cdd6f6 ("virtio: use virtio accessor to access packed event")
switched using of address_space_read_cached() to virito_lduw_phys_cached()
to access packed descriptor event.
When we used address_space_read_cached(), we needed to call
virtio_tswap16s() to handle the endianess of the field, but
virito_lduw_phys_cached() already handles it internally, so we no longer
need to call virtio_tswap16s() (as the commit had done for `off_wrap`,
but forgot for `flags`).
Fixes: d152cdd6f6 ("virtio: use virtio accessor to access packed event")
Cc: jasowang@redhat.com
Cc: qemu-stable@nongnu.org
Reported-by: Xoykie <xoykie@gmail.com>
Link: https://lore.kernel.org/qemu-devel/CAFU8RB_pjr77zMLsM0Unf9xPNxfr_--Tjr49F_eX32ZBc5o2zQ@mail.gmail.com
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
hw/virtio/virtio.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 893a072c9d..2e5e67bdb9 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -323,7 +323,6 @@ static void vring_packed_event_read(VirtIODevice *vdev,
/* Make sure flags is seen before off_wrap */
smp_rmb();
e->off_wrap = virtio_lduw_phys_cached(vdev, cache, off_off);
- virtio_tswap16s(vdev, &e->flags);
}
static void vring_packed_off_wrap_write(VirtIODevice *vdev,
--
2.45.2
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] virtio: remove virtio_tswap16s() call in vring_packed_event_read()
2024-07-01 7:52 [PATCH] virtio: remove virtio_tswap16s() call in vring_packed_event_read() Stefano Garzarella
@ 2024-07-01 8:22 ` Jason Wang
2024-07-01 8:58 ` Peter Maydell
2024-07-01 9:53 ` Eugenio Perez Martin
2 siblings, 0 replies; 5+ messages in thread
From: Jason Wang @ 2024-07-01 8:22 UTC (permalink / raw)
To: Stefano Garzarella
Cc: qemu-devel, Eugenio Perez Martin, Peter Maydell,
Michael S. Tsirkin, qemu-stable, Xoykie
On Mon, Jul 1, 2024 at 3:52 PM Stefano Garzarella <sgarzare@redhat.com> wrote:
>
> Commit d152cdd6f6 ("virtio: use virtio accessor to access packed event")
> switched using of address_space_read_cached() to virito_lduw_phys_cached()
> to access packed descriptor event.
>
> When we used address_space_read_cached(), we needed to call
> virtio_tswap16s() to handle the endianess of the field, but
> virito_lduw_phys_cached() already handles it internally, so we no longer
> need to call virtio_tswap16s() (as the commit had done for `off_wrap`,
> but forgot for `flags`).
>
> Fixes: d152cdd6f6 ("virtio: use virtio accessor to access packed event")
> Cc: jasowang@redhat.com
> Cc: qemu-stable@nongnu.org
> Reported-by: Xoykie <xoykie@gmail.com>
> Link: https://lore.kernel.org/qemu-devel/CAFU8RB_pjr77zMLsM0Unf9xPNxfr_--Tjr49F_eX32ZBc5o2zQ@mail.gmail.com
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Thanks
> ---
> hw/virtio/virtio.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 893a072c9d..2e5e67bdb9 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -323,7 +323,6 @@ static void vring_packed_event_read(VirtIODevice *vdev,
> /* Make sure flags is seen before off_wrap */
> smp_rmb();
> e->off_wrap = virtio_lduw_phys_cached(vdev, cache, off_off);
> - virtio_tswap16s(vdev, &e->flags);
> }
>
> static void vring_packed_off_wrap_write(VirtIODevice *vdev,
> --
> 2.45.2
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] virtio: remove virtio_tswap16s() call in vring_packed_event_read()
2024-07-01 7:52 [PATCH] virtio: remove virtio_tswap16s() call in vring_packed_event_read() Stefano Garzarella
2024-07-01 8:22 ` Jason Wang
@ 2024-07-01 8:58 ` Peter Maydell
2024-07-01 9:53 ` Eugenio Perez Martin
2 siblings, 0 replies; 5+ messages in thread
From: Peter Maydell @ 2024-07-01 8:58 UTC (permalink / raw)
To: Stefano Garzarella
Cc: qemu-devel, Eugenio Perez Martin, jasowang, Michael S. Tsirkin,
qemu-stable, Xoykie
On Mon, 1 Jul 2024 at 08:52, Stefano Garzarella <sgarzare@redhat.com> wrote:
>
> Commit d152cdd6f6 ("virtio: use virtio accessor to access packed event")
> switched using of address_space_read_cached() to virito_lduw_phys_cached()
> to access packed descriptor event.
>
> When we used address_space_read_cached(), we needed to call
> virtio_tswap16s() to handle the endianess of the field, but
> virito_lduw_phys_cached() already handles it internally, so we no longer
> need to call virtio_tswap16s() (as the commit had done for `off_wrap`,
> but forgot for `flags`).
>
> Fixes: d152cdd6f6 ("virtio: use virtio accessor to access packed event")
> Cc: jasowang@redhat.com
> Cc: qemu-stable@nongnu.org
> Reported-by: Xoykie <xoykie@gmail.com>
> Link: https://lore.kernel.org/qemu-devel/CAFU8RB_pjr77zMLsM0Unf9xPNxfr_--Tjr49F_eX32ZBc5o2zQ@mail.gmail.com
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
> hw/virtio/virtio.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 893a072c9d..2e5e67bdb9 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -323,7 +323,6 @@ static void vring_packed_event_read(VirtIODevice *vdev,
> /* Make sure flags is seen before off_wrap */
> smp_rmb();
> e->off_wrap = virtio_lduw_phys_cached(vdev, cache, off_off);
> - virtio_tswap16s(vdev, &e->flags);
> }
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
thanks
-- PMM
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] virtio: remove virtio_tswap16s() call in vring_packed_event_read()
2024-07-01 7:52 [PATCH] virtio: remove virtio_tswap16s() call in vring_packed_event_read() Stefano Garzarella
2024-07-01 8:22 ` Jason Wang
2024-07-01 8:58 ` Peter Maydell
@ 2024-07-01 9:53 ` Eugenio Perez Martin
2024-07-01 10:32 ` Michael S. Tsirkin
2 siblings, 1 reply; 5+ messages in thread
From: Eugenio Perez Martin @ 2024-07-01 9:53 UTC (permalink / raw)
To: Stefano Garzarella
Cc: qemu-devel, jasowang, Peter Maydell, Michael S. Tsirkin,
qemu-stable, Xoykie, Lei Yang
On Mon, Jul 1, 2024 at 9:52 AM Stefano Garzarella <sgarzare@redhat.com> wrote:
>
> Commit d152cdd6f6 ("virtio: use virtio accessor to access packed event")
> switched using of address_space_read_cached() to virito_lduw_phys_cached()
> to access packed descriptor event.
>
> When we used address_space_read_cached(), we needed to call
> virtio_tswap16s() to handle the endianess of the field, but
> virito_lduw_phys_cached() already handles it internally, so we no longer
> need to call virtio_tswap16s() (as the commit had done for `off_wrap`,
> but forgot for `flags`).
>
> Fixes: d152cdd6f6 ("virtio: use virtio accessor to access packed event")
> Cc: jasowang@redhat.com
> Cc: qemu-stable@nongnu.org
> Reported-by: Xoykie <xoykie@gmail.com>
> Link: https://lore.kernel.org/qemu-devel/CAFU8RB_pjr77zMLsM0Unf9xPNxfr_--Tjr49F_eX32ZBc5o2zQ@mail.gmail.com
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Eugenio Pérez <eperezma@redhat.com>
I think it would be great to test the patches using a big endian host
just in case.
Thanks!
> ---
> hw/virtio/virtio.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 893a072c9d..2e5e67bdb9 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -323,7 +323,6 @@ static void vring_packed_event_read(VirtIODevice *vdev,
> /* Make sure flags is seen before off_wrap */
> smp_rmb();
> e->off_wrap = virtio_lduw_phys_cached(vdev, cache, off_off);
> - virtio_tswap16s(vdev, &e->flags);
> }
>
> static void vring_packed_off_wrap_write(VirtIODevice *vdev,
> --
> 2.45.2
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] virtio: remove virtio_tswap16s() call in vring_packed_event_read()
2024-07-01 9:53 ` Eugenio Perez Martin
@ 2024-07-01 10:32 ` Michael S. Tsirkin
0 siblings, 0 replies; 5+ messages in thread
From: Michael S. Tsirkin @ 2024-07-01 10:32 UTC (permalink / raw)
To: Eugenio Perez Martin
Cc: Stefano Garzarella, qemu-devel, jasowang, Peter Maydell,
qemu-stable, Xoykie, Lei Yang
On Mon, Jul 01, 2024 at 11:53:34AM +0200, Eugenio Perez Martin wrote:
> On Mon, Jul 1, 2024 at 9:52 AM Stefano Garzarella <sgarzare@redhat.com> wrote:
> >
> > Commit d152cdd6f6 ("virtio: use virtio accessor to access packed event")
> > switched using of address_space_read_cached() to virito_lduw_phys_cached()
> > to access packed descriptor event.
> >
> > When we used address_space_read_cached(), we needed to call
> > virtio_tswap16s() to handle the endianess of the field, but
> > virito_lduw_phys_cached() already handles it internally, so we no longer
> > need to call virtio_tswap16s() (as the commit had done for `off_wrap`,
> > but forgot for `flags`).
> >
> > Fixes: d152cdd6f6 ("virtio: use virtio accessor to access packed event")
> > Cc: jasowang@redhat.com
> > Cc: qemu-stable@nongnu.org
> > Reported-by: Xoykie <xoykie@gmail.com>
> > Link: https://lore.kernel.org/qemu-devel/CAFU8RB_pjr77zMLsM0Unf9xPNxfr_--Tjr49F_eX32ZBc5o2zQ@mail.gmail.com
> > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
>
> Reviewed-by: Eugenio Pérez <eperezma@redhat.com>
>
> I think it would be great to test the patches using a big endian host
> just in case.
>
> Thanks!
I think we really should move to using sparse tags for endian-ness,
like Linux does, and away from swap calls.
> > ---
> > hw/virtio/virtio.c | 1 -
> > 1 file changed, 1 deletion(-)
> >
> > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> > index 893a072c9d..2e5e67bdb9 100644
> > --- a/hw/virtio/virtio.c
> > +++ b/hw/virtio/virtio.c
> > @@ -323,7 +323,6 @@ static void vring_packed_event_read(VirtIODevice *vdev,
> > /* Make sure flags is seen before off_wrap */
> > smp_rmb();
> > e->off_wrap = virtio_lduw_phys_cached(vdev, cache, off_off);
> > - virtio_tswap16s(vdev, &e->flags);
> > }
> >
> > static void vring_packed_off_wrap_write(VirtIODevice *vdev,
> > --
> > 2.45.2
> >
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2024-07-01 10:33 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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2024-07-01 7:52 [PATCH] virtio: remove virtio_tswap16s() call in vring_packed_event_read() Stefano Garzarella
2024-07-01 8:22 ` Jason Wang
2024-07-01 8:58 ` Peter Maydell
2024-07-01 9:53 ` Eugenio Perez Martin
2024-07-01 10:32 ` Michael S. Tsirkin
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