* [PATCH 2/2] virtio-pci: check name when counting MSI-X vectors
2019-12-17 19:06 [PATCH 1/2] virtio-balloon: initialize all vq callbacks Daniel Verkamp
@ 2019-12-17 19:06 ` Daniel Verkamp
2019-12-17 20:04 ` Michael S. Tsirkin
` (2 more replies)
2019-12-17 20:05 ` [PATCH 1/2] virtio-balloon: initialize all vq callbacks Michael S. Tsirkin
` (2 subsequent siblings)
3 siblings, 3 replies; 11+ messages in thread
From: Daniel Verkamp @ 2019-12-17 19:06 UTC (permalink / raw)
To: virtualization; +Cc: Michael S. Tsirkin
VQs without a name specified are not valid; they are skipped in the
later loop that assigns MSI-X vectors to queues, but the per_vq_vectors
loop above that counts the required number of vectors previously still
counted any queue with a non-NULL callback as needing a vector.
Add a check to the per_vq_vectors loop so that vectors with no name are
not counted to make the two loops consistent. This prevents
over-counting unnecessary vectors (e.g. for features which were not
negotiated with the device).
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
---
drivers/virtio/virtio_pci_common.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index f2862f66c2ac..222d630c41fc 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -294,7 +294,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
/* Best option: one for change interrupt, one per vq. */
nvectors = 1;
for (i = 0; i < nvqs; ++i)
- if (callbacks[i])
+ if (names[i] && callbacks[i])
++nvectors;
} else {
/* Second best: one for change, shared for all vqs. */
--
2.24.1.735.g03f4e72817-goog
^ permalink raw reply related [flat|nested] 11+ messages in thread* Re: [PATCH 2/2] virtio-pci: check name when counting MSI-X vectors
2019-12-17 19:06 ` [PATCH 2/2] virtio-pci: check name when counting MSI-X vectors Daniel Verkamp
@ 2019-12-17 20:04 ` Michael S. Tsirkin
2019-12-18 5:19 ` Michael S. Tsirkin
2019-12-18 9:30 ` Cornelia Huck
2 siblings, 0 replies; 11+ messages in thread
From: Michael S. Tsirkin @ 2019-12-17 20:04 UTC (permalink / raw)
To: Daniel Verkamp; +Cc: virtualization
On Tue, Dec 17, 2019 at 11:06:10AM -0800, Daniel Verkamp wrote:
> VQs without a name specified are not valid; they are skipped in the
> later loop that assigns MSI-X vectors to queues, but the per_vq_vectors
> loop above that counts the required number of vectors previously still
> counted any queue with a non-NULL callback as needing a vector.
>
> Add a check to the per_vq_vectors loop so that vectors with no name are
> not counted to make the two loops consistent. This prevents
> over-counting unnecessary vectors (e.g. for features which were not
> negotiated with the device).
>
> Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
And I'll add:
Fixes: 9564e138b1f6 ("virtio: Add memory statistics reporting to the balloon driver (V4)")
here too.
> ---
> drivers/virtio/virtio_pci_common.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> index f2862f66c2ac..222d630c41fc 100644
> --- a/drivers/virtio/virtio_pci_common.c
> +++ b/drivers/virtio/virtio_pci_common.c
> @@ -294,7 +294,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
> /* Best option: one for change interrupt, one per vq. */
> nvectors = 1;
> for (i = 0; i < nvqs; ++i)
> - if (callbacks[i])
> + if (names[i] && callbacks[i])
> ++nvectors;
> } else {
> /* Second best: one for change, shared for all vqs. */
> --
> 2.24.1.735.g03f4e72817-goog
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH 2/2] virtio-pci: check name when counting MSI-X vectors
2019-12-17 19:06 ` [PATCH 2/2] virtio-pci: check name when counting MSI-X vectors Daniel Verkamp
2019-12-17 20:04 ` Michael S. Tsirkin
@ 2019-12-18 5:19 ` Michael S. Tsirkin
2019-12-18 9:30 ` Cornelia Huck
2 siblings, 0 replies; 11+ messages in thread
From: Michael S. Tsirkin @ 2019-12-18 5:19 UTC (permalink / raw)
To: Daniel Verkamp; +Cc: virtualization
On Tue, Dec 17, 2019 at 11:06:10AM -0800, Daniel Verkamp wrote:
> VQs without a name specified are not valid; they are skipped in the
> later loop that assigns MSI-X vectors to queues, but the per_vq_vectors
> loop above that counts the required number of vectors previously still
> counted any queue with a non-NULL callback as needing a vector.
>
> Add a check to the per_vq_vectors loop so that vectors with no name are
> not counted to make the two loops consistent. This prevents
> over-counting unnecessary vectors (e.g. for features which were not
> negotiated with the device).
>
> Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
OK so I will add
Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
here too?
> ---
> drivers/virtio/virtio_pci_common.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> index f2862f66c2ac..222d630c41fc 100644
> --- a/drivers/virtio/virtio_pci_common.c
> +++ b/drivers/virtio/virtio_pci_common.c
> @@ -294,7 +294,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
> /* Best option: one for change interrupt, one per vq. */
> nvectors = 1;
> for (i = 0; i < nvqs; ++i)
> - if (callbacks[i])
> + if (names[i] && callbacks[i])
> ++nvectors;
> } else {
> /* Second best: one for change, shared for all vqs. */
> --
> 2.24.1.735.g03f4e72817-goog
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH 2/2] virtio-pci: check name when counting MSI-X vectors
2019-12-17 19:06 ` [PATCH 2/2] virtio-pci: check name when counting MSI-X vectors Daniel Verkamp
2019-12-17 20:04 ` Michael S. Tsirkin
2019-12-18 5:19 ` Michael S. Tsirkin
@ 2019-12-18 9:30 ` Cornelia Huck
2 siblings, 0 replies; 11+ messages in thread
From: Cornelia Huck @ 2019-12-18 9:30 UTC (permalink / raw)
To: Daniel Verkamp; +Cc: Michael S. Tsirkin, virtualization
On Tue, 17 Dec 2019 11:06:10 -0800
Daniel Verkamp <dverkamp@chromium.org> wrote:
> VQs without a name specified are not valid; they are skipped in the
> later loop that assigns MSI-X vectors to queues, but the per_vq_vectors
> loop above that counts the required number of vectors previously still
> counted any queue with a non-NULL callback as needing a vector.
>
> Add a check to the per_vq_vectors loop so that vectors with no name are
> not counted to make the two loops consistent. This prevents
> over-counting unnecessary vectors (e.g. for features which were not
> negotiated with the device).
>
> Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
> ---
> drivers/virtio/virtio_pci_common.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> index f2862f66c2ac..222d630c41fc 100644
> --- a/drivers/virtio/virtio_pci_common.c
> +++ b/drivers/virtio/virtio_pci_common.c
> @@ -294,7 +294,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
> /* Best option: one for change interrupt, one per vq. */
> nvectors = 1;
> for (i = 0; i < nvqs; ++i)
> - if (callbacks[i])
> + if (names[i] && callbacks[i])
> ++nvectors;
> } else {
> /* Second best: one for change, shared for all vqs. */
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 1/2] virtio-balloon: initialize all vq callbacks
2019-12-17 19:06 [PATCH 1/2] virtio-balloon: initialize all vq callbacks Daniel Verkamp
2019-12-17 19:06 ` [PATCH 2/2] virtio-pci: check name when counting MSI-X vectors Daniel Verkamp
@ 2019-12-17 20:05 ` Michael S. Tsirkin
2019-12-17 20:10 ` Daniel Verkamp
2019-12-18 3:18 ` Wei Wang
2019-12-18 9:28 ` Cornelia Huck
3 siblings, 1 reply; 11+ messages in thread
From: Michael S. Tsirkin @ 2019-12-17 20:05 UTC (permalink / raw)
To: Daniel Verkamp; +Cc: virtualization
On Tue, Dec 17, 2019 at 11:06:09AM -0800, Daniel Verkamp wrote:
> Ensure that elements of the array that correspond to unavailable
> features are set to NULL; previously, they would be left uninitialized.
>
> Since the corresponding names array elements were explicitly set to
> NULL, the uninitialized callback pointers would not actually be
> dereferenced; however, the uninitialized callbacks elements would still
> be read in vp_find_vqs_msix() and used to calculate the number of MSI-X
> vectors required.
>
> Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
> Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Actually, we already have the issue with the stats VQ, no?
So I think this one is more appropriate:
Fixes: 9564e138b1f6 ("virtio: Add memory statistics reporting to the balloon driver (V4)")
> ---
> drivers/virtio/virtio_balloon.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 93f995f6cf36..8e400ece9273 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -475,7 +475,9 @@ static int init_vqs(struct virtio_balloon *vb)
> names[VIRTIO_BALLOON_VQ_INFLATE] = "inflate";
> callbacks[VIRTIO_BALLOON_VQ_DEFLATE] = balloon_ack;
> names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate";
> + callbacks[VIRTIO_BALLOON_VQ_STATS] = NULL;
> names[VIRTIO_BALLOON_VQ_STATS] = NULL;
> + callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
> names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
>
> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
> --
> 2.24.1.735.g03f4e72817-goog
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH 1/2] virtio-balloon: initialize all vq callbacks
2019-12-17 20:05 ` [PATCH 1/2] virtio-balloon: initialize all vq callbacks Michael S. Tsirkin
@ 2019-12-17 20:10 ` Daniel Verkamp
0 siblings, 0 replies; 11+ messages in thread
From: Daniel Verkamp @ 2019-12-17 20:10 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: virtualization
On Tue, Dec 17, 2019 at 12:05 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Tue, Dec 17, 2019 at 11:06:09AM -0800, Daniel Verkamp wrote:
> > Ensure that elements of the array that correspond to unavailable
> > features are set to NULL; previously, they would be left uninitialized.
> >
> > Since the corresponding names array elements were explicitly set to
> > NULL, the uninitialized callback pointers would not actually be
> > dereferenced; however, the uninitialized callbacks elements would still
> > be read in vp_find_vqs_msix() and used to calculate the number of MSI-X
> > vectors required.
> >
> > Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
> > Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
>
> Actually, we already have the issue with the stats VQ, no?
>
> So I think this one is more appropriate:
> Fixes: 9564e138b1f6 ("virtio: Add memory statistics reporting to the balloon driver (V4)")
I think things were OK in 9564e138b1f6 because nvqs was calculated
based on the available features, so the later elements of the array
would not have been inspected by find_vqs. 86a559787e6f introduced
the uninitialized array elements as well as the removal of dynamic
nvqs based on features.
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 1/2] virtio-balloon: initialize all vq callbacks
2019-12-17 19:06 [PATCH 1/2] virtio-balloon: initialize all vq callbacks Daniel Verkamp
2019-12-17 19:06 ` [PATCH 2/2] virtio-pci: check name when counting MSI-X vectors Daniel Verkamp
2019-12-17 20:05 ` [PATCH 1/2] virtio-balloon: initialize all vq callbacks Michael S. Tsirkin
@ 2019-12-18 3:18 ` Wei Wang
2019-12-18 5:19 ` Michael S. Tsirkin
2019-12-18 9:28 ` Cornelia Huck
3 siblings, 1 reply; 11+ messages in thread
From: Wei Wang @ 2019-12-18 3:18 UTC (permalink / raw)
To: Daniel Verkamp, virtualization; +Cc: Michael S. Tsirkin
On 12/18/2019 03:06 AM, Daniel Verkamp wrote:
> Ensure that elements of the array that correspond to unavailable
> features are set to NULL; previously, they would be left uninitialized.
>
> Since the corresponding names array elements were explicitly set to
> NULL, the uninitialized callback pointers would not actually be
> dereferenced; however, the uninitialized callbacks elements would still
> be read in vp_find_vqs_msix() and used to calculate the number of MSI-X
> vectors required.
With your 2nd patch:
if (names[i] && callbacks[i])
++nvectors;
It seems this patch isn't necessary as names[i] is already NULL, isn't it?
Best,
Wei
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH 1/2] virtio-balloon: initialize all vq callbacks
2019-12-18 3:18 ` Wei Wang
@ 2019-12-18 5:19 ` Michael S. Tsirkin
2019-12-18 6:06 ` Wei Wang
0 siblings, 1 reply; 11+ messages in thread
From: Michael S. Tsirkin @ 2019-12-18 5:19 UTC (permalink / raw)
To: Wei Wang; +Cc: virtualization
On Wed, Dec 18, 2019 at 11:18:45AM +0800, Wei Wang wrote:
> On 12/18/2019 03:06 AM, Daniel Verkamp wrote:
> > Ensure that elements of the array that correspond to unavailable
> > features are set to NULL; previously, they would be left uninitialized.
> >
> > Since the corresponding names array elements were explicitly set to
> > NULL, the uninitialized callback pointers would not actually be
> > dereferenced; however, the uninitialized callbacks elements would still
> > be read in vp_find_vqs_msix() and used to calculate the number of MSI-X
> > vectors required.
>
> With your 2nd patch:
> if (names[i] && callbacks[i])
> ++nvectors;
>
> It seems this patch isn't necessary as names[i] is already NULL, isn't it?
>
> Best,
> Wei
Right but passing uninitialized values isn't nice even if
the function called happens to ignore them.
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 1/2] virtio-balloon: initialize all vq callbacks
2019-12-18 5:19 ` Michael S. Tsirkin
@ 2019-12-18 6:06 ` Wei Wang
0 siblings, 0 replies; 11+ messages in thread
From: Wei Wang @ 2019-12-18 6:06 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: virtualization
On 12/18/2019 01:19 PM, Michael S. Tsirkin wrote:
> On Wed, Dec 18, 2019 at 11:18:45AM +0800, Wei Wang wrote:
>> On 12/18/2019 03:06 AM, Daniel Verkamp wrote:
>>> Ensure that elements of the array that correspond to unavailable
>>> features are set to NULL; previously, they would be left uninitialized.
>>>
>>> Since the corresponding names array elements were explicitly set to
>>> NULL, the uninitialized callback pointers would not actually be
>>> dereferenced; however, the uninitialized callbacks elements would still
>>> be read in vp_find_vqs_msix() and used to calculate the number of MSI-X
>>> vectors required.
>> With your 2nd patch:
>> if (names[i] && callbacks[i])
>> ++nvectors;
>>
>> It seems this patch isn't necessary as names[i] is already NULL, isn't it?
>>
>> Best,
>> Wei
> Right but passing uninitialized values isn't nice even if
> the function called happens to ignore them.
Hmm.. then please make one more change:
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
names[VIRTIO_BALLOON_VQ_FREE_PAGE] = "free_page_vq";
- callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
}
And I think all the commit description isn't accurate then, it seems to
be a coding style improvement,
instead of affecting "calculate the number of MSI-X vectors required".
Best,
Wei
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 1/2] virtio-balloon: initialize all vq callbacks
2019-12-17 19:06 [PATCH 1/2] virtio-balloon: initialize all vq callbacks Daniel Verkamp
` (2 preceding siblings ...)
2019-12-18 3:18 ` Wei Wang
@ 2019-12-18 9:28 ` Cornelia Huck
3 siblings, 0 replies; 11+ messages in thread
From: Cornelia Huck @ 2019-12-18 9:28 UTC (permalink / raw)
To: Daniel Verkamp; +Cc: Michael S. Tsirkin, virtualization
On Tue, 17 Dec 2019 11:06:09 -0800
Daniel Verkamp <dverkamp@chromium.org> wrote:
> Ensure that elements of the array that correspond to unavailable
s/array/callbacks array/ ?
> features are set to NULL; previously, they would be left uninitialized.
>
> Since the corresponding names array elements were explicitly set to
> NULL, the uninitialized callback pointers would not actually be
> dereferenced; however, the uninitialized callbacks elements would still
> be read in vp_find_vqs_msix() and used to calculate the number of MSI-X
> vectors required.
>
> Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
> Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
> ---
> drivers/virtio/virtio_balloon.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 93f995f6cf36..8e400ece9273 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -475,7 +475,9 @@ static int init_vqs(struct virtio_balloon *vb)
> names[VIRTIO_BALLOON_VQ_INFLATE] = "inflate";
> callbacks[VIRTIO_BALLOON_VQ_DEFLATE] = balloon_ack;
> names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate";
> + callbacks[VIRTIO_BALLOON_VQ_STATS] = NULL;
> names[VIRTIO_BALLOON_VQ_STATS] = NULL;
> + callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
> names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
>
> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
Alternatively, it might make sense to zero the whole array and drop the
explicit NULL assignments, which would also be a bit more future
proof... but this one fixes things as well, of course.
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
^ permalink raw reply [flat|nested] 11+ messages in thread