similar to: [PATCH] virtio: harsher barriers for virtio-mmio.

Currently a host kick error is silently ignored and not reflected in the virtqueue of a particular virtio device. Changing the notify API for guest->host notification seems to be one prerequisite in order to be able to handle such errors in the context where the kick is triggered. This patch changes the notify API. The notify function must return a negative int return value in case the host

virtio ring uses smp_wmb on SMP and wmb on !SMP, the reason for the later being that it might be talking to another kernel on the same SMP machine. This is exactly what __smp_XXX barriers do, so switch to these instead of homegrown ifdef hacks. Cc: Peter Zijlstra <peterz at infradead.org> Cc: Alexander Duyck <alexander.duyck at gmail.com> Signed-off-by: Michael S. Tsirkin <mst at

On Tue, Apr 07, 2015 at 05:47:42PM -0700, Alexander Duyck wrote: > This change makes it so that instead of using smp_wmb/rmb which varies > depending on the kernel configuration we can can use dma_wmb/rmb which for > most architectures should be equal to or slightly more strict than > smp_wmb/rmb. > > The advantage to this is that these barriers are available to uniprocessor

This change makes it so that instead of using smp_wmb/rmb which varies depending on the kernel configuration we can can use dma_wmb/rmb which for most architectures should be equal to or slightly more strict than smp_wmb/rmb. The advantage to this is that these barriers are available to uniprocessor builds as well so the performance should improve under such a configuration. Signed-off-by:

This change makes it so that instead of using smp_wmb/rmb which varies depending on the kernel configuration we can can use dma_wmb/rmb which for most architectures should be equal to or slightly more strict than smp_wmb/rmb. The advantage to this is that these barriers are available to uniprocessor builds as well so the performance should improve under such a configuration. Signed-off-by:

Virtio is using memory barriers to control the ordering of references to the vrings on SMP systems. When the guest is compiled with SMP support, virtio is only using SMP barriers in order to avoid incurring the overhead involved with mandatory barriers. Lately, though, virtio is being increasingly used with inter-processor communication scenarios too, which involve running two (separate)

Virtio is using memory barriers to control the ordering of references to the vrings on SMP systems. When the guest is compiled with SMP support, virtio is only using SMP barriers in order to avoid incurring the overhead involved with mandatory barriers. Lately, though, virtio is being increasingly used with inter-processor communication scenarios too, which involve running two (separate)

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git