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This series fixes issues with variable initialization in the virtio balloon driver which manifest as the driver sending invalid memory stats to the host. v1->v2: * Call update_balloon_stats instead of filling the buffer with invalid tags. * Add BUG_ON to update_balloon_stats to formalize the invariant that all slots in the buffer must be initialized. v2->v3: * Remove BUG_ON and

This series fixes issues with variable initialization in the virtio balloon driver which manifest as the driver sending invalid memory stats to the host. v1->v2: * Call update_balloon_stats instead of filling the buffer with invalid tags. * Add BUG_ON to update_balloon_stats to formalize the invariant that all slots in the buffer must be initialized. v2->v3: * Remove BUG_ON and

...ed by the host. The alternative fix would be to push an empty buffer in init_vqs but that's not easily done with the current virtio implementation and would still not eliminate the invariant that update_balloon_stats has to update all VIRTIO_BALLOON_S_NR fields. Signed-off-by: Ladi Prosek <lprosek at redhat.com> --- drivers/virtio/virtio_balloon.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 4e11915..d34f56f 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -423,12 +423,...

...ed by the host. The alternative fix would be to push an empty buffer in init_vqs but that's not easily done with the current virtio implementation and would still not eliminate the invariant that update_balloon_stats has to update all VIRTIO_BALLOON_S_NR fields. Signed-off-by: Ladi Prosek <lprosek at redhat.com> --- drivers/virtio/virtio_balloon.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 4e11915..d34f56f 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -423,12 +423,...

...e to push an empty buffer in init_vqs but >> that's not easily done with the current virtio implementation and >> would still not eliminate the invariant that update_balloon_stats >> has to update all VIRTIO_BALLOON_S_NR fields. >> >> Signed-off-by: Ladi Prosek <lprosek at redhat.com> >> --- >> drivers/virtio/virtio_balloon.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c >> index 4e11915..d34f56f 100644 >> --- a/drivers/virtio/virtio_ba...

...e to push an empty buffer in init_vqs but >> that's not easily done with the current virtio implementation and >> would still not eliminate the invariant that update_balloon_stats >> has to update all VIRTIO_BALLOON_S_NR fields. >> >> Signed-off-by: Ladi Prosek <lprosek at redhat.com> >> --- >> drivers/virtio/virtio_balloon.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c >> index 4e11915..d34f56f 100644 >> --- a/drivers/virtio/virtio_ba...

...ementation and violates the spec "Driver MUST supply the same subset of statistics in all buffers submitted to the statsq". * Push a buffer with invalid tags in init_vqs. Violates the same spec clause, plus "invalid tag" is not really defined. Signed-off-by: Ladi Prosek <lprosek at redhat.com> --- v1->v2: * Call update_balloon_stats instead of filling the buffer with invalid tags. * Add BUG_ON to update_balloon_stats to formalize the invariant that all slots in the buffer must be initialized. Also, I just noticed this paragraph in the spec: "When using...

...ementation and violates the spec "Driver MUST supply the same subset of statistics in all buffers submitted to the statsq". * Push a buffer with invalid tags in init_vqs. Violates the same spec clause, plus "invalid tag" is not really defined. Signed-off-by: Ladi Prosek <lprosek at redhat.com> --- v1->v2: * Call update_balloon_stats instead of filling the buffer with invalid tags. * Add BUG_ON to update_balloon_stats to formalize the invariant that all slots in the buffer must be initialized. Also, I just noticed this paragraph in the spec: "When using...

On Fri, Mar 24, 2017 at 09:40:07PM +0100, Arnd Bergmann wrote: > On Fri, Mar 24, 2017 at 9:11 PM, Ladi Prosek <lprosek at redhat.com> wrote: > > On Fri, Mar 24, 2017 at 7:38 PM, David Hildenbrand <david at redhat.com> wrote: > >> On 23.03.2017 16:17, Arnd Bergmann wrote: > >>> The latest gcc-7.0.1 snapshot reports a new warning: > >>> > >>> virtio/virtio_b...

On Fri, Mar 24, 2017 at 09:40:07PM +0100, Arnd Bergmann wrote: > On Fri, Mar 24, 2017 at 9:11 PM, Ladi Prosek <lprosek at redhat.com> wrote: > > On Fri, Mar 24, 2017 at 7:38 PM, David Hildenbrand <david at redhat.com> wrote: > >> On 23.03.2017 16:17, Arnd Bergmann wrote: > >>> The latest gcc-7.0.1 snapshot reports a new warning: > >>> > >>> virtio/virtio_b...

On Mon, Mar 27, 2017 at 12:02:33PM +0200, Ladi Prosek wrote: > On Fri, Mar 24, 2017 at 9:59 PM, Michael S. Tsirkin <mst at redhat.com> wrote: > > On Fri, Mar 24, 2017 at 09:40:07PM +0100, Arnd Bergmann wrote: > >> On Fri, Mar 24, 2017 at 9:11 PM, Ladi Prosek <lprosek at redhat.com> wrote: > >> > On Fri, Mar 24, 2017 at 7:38 PM, David Hildenbrand <david at redhat.com> wrote: > >> >> On 23.03.2017 16:17, Arnd Bergmann wrote: > >> >>> The latest gcc-7.0.1 snapshot reports a new warning: > >> >>&g...

On Mon, Mar 27, 2017 at 12:02:33PM +0200, Ladi Prosek wrote: > On Fri, Mar 24, 2017 at 9:59 PM, Michael S. Tsirkin <mst at redhat.com> wrote: > > On Fri, Mar 24, 2017 at 09:40:07PM +0100, Arnd Bergmann wrote: > >> On Fri, Mar 24, 2017 at 9:11 PM, Ladi Prosek <lprosek at redhat.com> wrote: > >> > On Fri, Mar 24, 2017 at 7:38 PM, David Hildenbrand <david at redhat.com> wrote: > >> >> On 23.03.2017 16:17, Arnd Bergmann wrote: > >> >>> The latest gcc-7.0.1 snapshot reports a new warning: > >> >>&g...

On Fri, Mar 24, 2017 at 7:38 PM, David Hildenbrand <david at redhat.com> wrote: > On 23.03.2017 16:17, Arnd Bergmann wrote: >> The latest gcc-7.0.1 snapshot reports a new warning: >> >> virtio/virtio_balloon.c: In function 'update_balloon_stats': >> virtio/virtio_balloon.c:258:26: error: 'events[2]' is used uninitialized in this function

On Fri, Mar 24, 2017 at 7:38 PM, David Hildenbrand <david at redhat.com> wrote: > On 23.03.2017 16:17, Arnd Bergmann wrote: >> The latest gcc-7.0.1 snapshot reports a new warning: >> >> virtio/virtio_balloon.c: In function 'update_balloon_stats': >> virtio/virtio_balloon.c:258:26: error: 'events[2]' is used uninitialized in this function

...rnative fix would be to push an empty buffer in init_vqs but > that's not easily done with the current virtio implementation and > would still not eliminate the invariant that update_balloon_stats > has to update all VIRTIO_BALLOON_S_NR fields. > > Signed-off-by: Ladi Prosek <lprosek at redhat.com> > --- > drivers/virtio/virtio_balloon.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index 4e11915..d34f56f 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/...

...tistics. >From all I can tell, this has been broken since the statistics code was originally added in 2.6.34. Fixes: 9564e138b1f6 ("virtio: Add memory statistics reporting to the balloon driver (V4)") Signed-off-by: Arnd Bergmann <arnd at arndb.de> Signed-off-by: Ladi Prosek <lprosek at redhat.com> Signed-off-by: Michael S. Tsirkin <mst at redhat.com> [arnd: backported to 4.4] Signed-off-by: Arnd Bergmann <arnd at arndb.de> --- drivers/virtio/virtio_balloon.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/...

...in init_vqs but > >> that's not easily done with the current virtio implementation and > >> would still not eliminate the invariant that update_balloon_stats > >> has to update all VIRTIO_BALLOON_S_NR fields. > >> > >> Signed-off-by: Ladi Prosek <lprosek at redhat.com> > >> --- > >> drivers/virtio/virtio_balloon.c | 4 ++++ > >> 1 file changed, 4 insertions(+) > >> > >> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > >> index 4e11915..d34f56f 100644 > >...

...buffers to the stats virtqueue. Note that it is still out of spec to change the number of counters at run-time. "Driver MUST supply the same subset of statistics in all buffers submitted to the statsq." Suggested-by: Arnd Bergmann <arnd at arndb.de> Signed-off-by: Ladi Prosek <lprosek at redhat.com> --- drivers/virtio/virtio_balloon.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index fcd06e1..d9544db 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/vi...

...d by ~0.5% in vring_bench. Writes to the used event field (vring_used_event) are still unconditional. Cc: Michael S. Tsirkin <mst at redhat.com> Cc: <stable at vger.kernel.org> # f277ec4 virtio_ring: shadow available Cc: <stable at vger.kernel.org> Signed-off-by: Ladi Prosek <lprosek at redhat.com> --- v1->v2: * fixed coding style * perf measurement results added to commit message * patch sent to virtualization at lists.linux-foundation.org (was kvm at vger.kernel.org) drivers/virtio/virtio_ring.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) d...

...d by ~0.5% in vring_bench. Writes to the used event field (vring_used_event) are still unconditional. Cc: Michael S. Tsirkin <mst at redhat.com> Cc: <stable at vger.kernel.org> # f277ec4 virtio_ring: shadow available Cc: <stable at vger.kernel.org> Signed-off-by: Ladi Prosek <lprosek at redhat.com> --- v1->v2: * fixed coding style * perf measurement results added to commit message * patch sent to virtualization at lists.linux-foundation.org (was kvm at vger.kernel.org) drivers/virtio/virtio_ring.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) d...