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SubjectRe: [PATCH net-next 8/8] vhost: event suppression for packed ring
On Wed, Jul 04, 2018 at 01:23:18PM +0800, Jason Wang wrote:
>
>
> On 2018年07月04日 12:13, Wei Xu wrote:
> >On Tue, Jul 03, 2018 at 01:38:04PM +0800, Jason Wang wrote:
> >>This patch introduces support for event suppression. This is done by
> >>have a two areas: device area and driver area. One side could then try
> >>to disable or enable (delayed) notification from other side by using a
> >>boolean hint or event index interface in the areas.
> >>
> >>For more information, please refer Virtio spec.
> >>
> >>Signed-off-by: Jason Wang<jasowang@redhat.com>
> >>---
> >> drivers/vhost/vhost.c | 191 ++++++++++++++++++++++++++++++++++++++++++++++----
> >> drivers/vhost/vhost.h | 10 ++-
> >> 2 files changed, 185 insertions(+), 16 deletions(-)
> >>
> >>diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> >>index 0f3f07c..cccbc82 100644
> >>--- a/drivers/vhost/vhost.c
> >>+++ b/drivers/vhost/vhost.c
> >>@@ -1115,10 +1115,15 @@ static int vq_access_ok_packed(struct vhost_virtqueue *vq, unsigned int num,
> >> struct vring_used __user *used)
> >> {
> >> struct vring_desc_packed *packed = (struct vring_desc_packed *)desc;
> >>+ struct vring_packed_desc_event *driver_event =
> >>+ (struct vring_packed_desc_event *)avail;
> >>+ struct vring_packed_desc_event *device_event =
> >>+ (struct vring_packed_desc_event *)used;
> >>- /* TODO: check device area and driver area */
> >> return access_ok(VERIFY_READ, packed, num * sizeof(*packed)) &&
> >>- access_ok(VERIFY_WRITE, packed, num * sizeof(*packed));
> >>+ access_ok(VERIFY_WRITE, packed, num * sizeof(*packed)) &&
> >R/W parameter doesn't make sense to most architectures and the comment in x86
> >says WRITE is a superset of READ, is it possible to converge them here?
> >
> >/**
> > * access_ok: - Checks if a user space pointer is valid
> > * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that
> > * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
> > * to write to a block, it is always safe to read from it.
> > * @addr: User space pointer to start of block to check
> > * @size: Size of block to check
> > *
> > * Context: User context only. This function may sleep if pagefaults are
> > * enabled.
> > *
> > * Checks if a pointer to a block of memory in user space is valid.
> > *
> > * Returns true (nonzero) if the memory block may be valid, false (zero)
> > * if it is definitely invalid.
> > *
> > * Note that, depending on architecture, this function probably just
> > * checks that the pointer is in the user space range - after calling
> > * this function, memory access functions may still return -EFAULT.
> > */
> >#define access_ok(type, addr, size)
> >......
> >
> >Thanks,
> >Wei
> >
>
> Well, this is a question that beyond the scope of this patch.
>
> My understanding is we should keep it unless type was meaningless on all
> archs.

No problem, go ahead.

Wei

>
> Thanks
>

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