include/hw/virtio/vhost-vdpa.h | 1 + hw/virtio/vhost-vdpa.c | 35 ++++++++++++++++++++++------------ 2 files changed, 24 insertions(+), 12 deletions(-)
With the introduction of the batch hinting, meaningless batches can be
created with no IOTLB updates if the memory region was skipped by
vhost_vdpa_listener_skipped_section. This is the case of host notifiers
memory regions, device un/realize, and others. This causes the vdpa
device to receive dma mapping settings with no changes, a possibly
expensive operation for nothing.
To avoid that, VHOST_IOTLB_BATCH_BEGIN hint is delayed until we have a
meaningful (not skipped section) mapping or unmapping operation, and
VHOST_IOTLB_BATCH_END is not written unless at least one of _UPDATE /
_INVALIDATE has been issued.
v3:
* Use a bool instead of a counter avoiding potential number wrapping
* Fix bad check on _commit
* Move VHOST_BACKEND_F_IOTLB_BATCH check to
vhost_vdpa_iotlb_batch_begin_once
v2 (from RFC):
* Rename misleading name
* Abstract start batching function for listener_add/del
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
include/hw/virtio/vhost-vdpa.h | 1 +
hw/virtio/vhost-vdpa.c | 35 ++++++++++++++++++++++------------
2 files changed, 24 insertions(+), 12 deletions(-)
diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h
index e98e327f12..6b9288fef8 100644
--- a/include/hw/virtio/vhost-vdpa.h
+++ b/include/hw/virtio/vhost-vdpa.h
@@ -23,6 +23,7 @@ typedef struct vhost_vdpa {
int device_fd;
int index;
uint32_t msg_type;
+ bool iotlb_batch_begin_sent;
MemoryListener listener;
struct vhost_dev *dev;
VhostVDPAHostNotifier notifier[VIRTIO_QUEUE_MAX];
diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index 6ce94a1f4d..93b7db61d1 100644
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c
@@ -89,19 +89,13 @@ static int vhost_vdpa_dma_unmap(struct vhost_vdpa *v, hwaddr iova,
return ret;
}
-static void vhost_vdpa_listener_begin(MemoryListener *listener)
+static void vhost_vdpa_listener_begin_batch(struct vhost_vdpa *v)
{
- struct vhost_vdpa *v = container_of(listener, struct vhost_vdpa, listener);
- struct vhost_dev *dev = v->dev;
- struct vhost_msg_v2 msg = {};
int fd = v->device_fd;
-
- if (!(dev->backend_cap & (0x1ULL << VHOST_BACKEND_F_IOTLB_BATCH))) {
- return;
- }
-
- msg.type = v->msg_type;
- msg.iotlb.type = VHOST_IOTLB_BATCH_BEGIN;
+ struct vhost_msg_v2 msg = {
+ .type = v->msg_type,
+ .iotlb.type = VHOST_IOTLB_BATCH_BEGIN,
+ };
if (write(fd, &msg, sizeof(msg)) != sizeof(msg)) {
error_report("failed to write, fd=%d, errno=%d (%s)",
@@ -109,6 +103,16 @@ static void vhost_vdpa_listener_begin(MemoryListener *listener)
}
}
+static void vhost_vdpa_iotlb_batch_begin_once(struct vhost_vdpa *v)
+{
+ if (v->dev->backend_cap & (0x1ULL << VHOST_BACKEND_F_IOTLB_BATCH) &&
+ !v->iotlb_batch_begin_sent) {
+ vhost_vdpa_listener_begin_batch(v);
+ }
+
+ v->iotlb_batch_begin_sent = true;
+}
+
static void vhost_vdpa_listener_commit(MemoryListener *listener)
{
struct vhost_vdpa *v = container_of(listener, struct vhost_vdpa, listener);
@@ -120,6 +124,10 @@ static void vhost_vdpa_listener_commit(MemoryListener *listener)
return;
}
+ if (!v->iotlb_batch_begin_sent) {
+ return;
+ }
+
msg.type = v->msg_type;
msg.iotlb.type = VHOST_IOTLB_BATCH_END;
@@ -127,6 +135,8 @@ static void vhost_vdpa_listener_commit(MemoryListener *listener)
error_report("failed to write, fd=%d, errno=%d (%s)",
fd, errno, strerror(errno));
}
+
+ v->iotlb_batch_begin_sent = false;
}
static void vhost_vdpa_listener_region_add(MemoryListener *listener,
@@ -170,6 +180,7 @@ static void vhost_vdpa_listener_region_add(MemoryListener *listener,
llsize = int128_sub(llend, int128_make64(iova));
+ vhost_vdpa_iotlb_batch_begin_once(v);
ret = vhost_vdpa_dma_map(v, iova, int128_get64(llsize),
vaddr, section->readonly);
if (ret) {
@@ -221,6 +232,7 @@ static void vhost_vdpa_listener_region_del(MemoryListener *listener,
llsize = int128_sub(llend, int128_make64(iova));
+ vhost_vdpa_iotlb_batch_begin_once(v);
ret = vhost_vdpa_dma_unmap(v, iova, int128_get64(llsize));
if (ret) {
error_report("vhost_vdpa dma unmap error!");
@@ -234,7 +246,6 @@ static void vhost_vdpa_listener_region_del(MemoryListener *listener,
* depends on the addnop().
*/
static const MemoryListener vhost_vdpa_memory_listener = {
- .begin = vhost_vdpa_listener_begin,
.commit = vhost_vdpa_listener_commit,
.region_add = vhost_vdpa_listener_region_add,
.region_del = vhost_vdpa_listener_region_del,
--
2.27.0
On Thu, Aug 12, 2021 at 10:09 PM Eugenio Pérez <eperezma@redhat.com> wrote: > > With the introduction of the batch hinting, meaningless batches can be > created with no IOTLB updates if the memory region was skipped by > vhost_vdpa_listener_skipped_section. This is the case of host notifiers > memory regions, device un/realize, and others. This causes the vdpa > device to receive dma mapping settings with no changes, a possibly > expensive operation for nothing. > > To avoid that, VHOST_IOTLB_BATCH_BEGIN hint is delayed until we have a > meaningful (not skipped section) mapping or unmapping operation, and > VHOST_IOTLB_BATCH_END is not written unless at least one of _UPDATE / > _INVALIDATE has been issued. Acked-by: Jason Wang <jasowang@redhat.com> > > v3: > * Use a bool instead of a counter avoiding potential number wrapping > * Fix bad check on _commit > * Move VHOST_BACKEND_F_IOTLB_BATCH check to > vhost_vdpa_iotlb_batch_begin_once > > v2 (from RFC): > * Rename misleading name > * Abstract start batching function for listener_add/del > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com> > --- > include/hw/virtio/vhost-vdpa.h | 1 + > hw/virtio/vhost-vdpa.c | 35 ++++++++++++++++++++++------------ > 2 files changed, 24 insertions(+), 12 deletions(-) > > diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h > index e98e327f12..6b9288fef8 100644 > --- a/include/hw/virtio/vhost-vdpa.h > +++ b/include/hw/virtio/vhost-vdpa.h > @@ -23,6 +23,7 @@ typedef struct vhost_vdpa { > int device_fd; > int index; > uint32_t msg_type; > + bool iotlb_batch_begin_sent; > MemoryListener listener; > struct vhost_dev *dev; > VhostVDPAHostNotifier notifier[VIRTIO_QUEUE_MAX]; > diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c > index 6ce94a1f4d..93b7db61d1 100644 > --- a/hw/virtio/vhost-vdpa.c > +++ b/hw/virtio/vhost-vdpa.c > @@ -89,19 +89,13 @@ static int vhost_vdpa_dma_unmap(struct vhost_vdpa *v, hwaddr iova, > return ret; > } > > -static void vhost_vdpa_listener_begin(MemoryListener *listener) > +static void vhost_vdpa_listener_begin_batch(struct vhost_vdpa *v) > { > - struct vhost_vdpa *v = container_of(listener, struct vhost_vdpa, listener); > - struct vhost_dev *dev = v->dev; > - struct vhost_msg_v2 msg = {}; > int fd = v->device_fd; > - > - if (!(dev->backend_cap & (0x1ULL << VHOST_BACKEND_F_IOTLB_BATCH))) { > - return; > - } > - > - msg.type = v->msg_type; > - msg.iotlb.type = VHOST_IOTLB_BATCH_BEGIN; > + struct vhost_msg_v2 msg = { > + .type = v->msg_type, > + .iotlb.type = VHOST_IOTLB_BATCH_BEGIN, > + }; > > if (write(fd, &msg, sizeof(msg)) != sizeof(msg)) { > error_report("failed to write, fd=%d, errno=%d (%s)", > @@ -109,6 +103,16 @@ static void vhost_vdpa_listener_begin(MemoryListener *listener) > } > } > > +static void vhost_vdpa_iotlb_batch_begin_once(struct vhost_vdpa *v) > +{ > + if (v->dev->backend_cap & (0x1ULL << VHOST_BACKEND_F_IOTLB_BATCH) && > + !v->iotlb_batch_begin_sent) { > + vhost_vdpa_listener_begin_batch(v); > + } > + > + v->iotlb_batch_begin_sent = true; > +} > + > static void vhost_vdpa_listener_commit(MemoryListener *listener) > { > struct vhost_vdpa *v = container_of(listener, struct vhost_vdpa, listener); > @@ -120,6 +124,10 @@ static void vhost_vdpa_listener_commit(MemoryListener *listener) > return; > } > > + if (!v->iotlb_batch_begin_sent) { > + return; > + } > + > msg.type = v->msg_type; > msg.iotlb.type = VHOST_IOTLB_BATCH_END; > > @@ -127,6 +135,8 @@ static void vhost_vdpa_listener_commit(MemoryListener *listener) > error_report("failed to write, fd=%d, errno=%d (%s)", > fd, errno, strerror(errno)); > } > + > + v->iotlb_batch_begin_sent = false; > } > > static void vhost_vdpa_listener_region_add(MemoryListener *listener, > @@ -170,6 +180,7 @@ static void vhost_vdpa_listener_region_add(MemoryListener *listener, > > llsize = int128_sub(llend, int128_make64(iova)); > > + vhost_vdpa_iotlb_batch_begin_once(v); > ret = vhost_vdpa_dma_map(v, iova, int128_get64(llsize), > vaddr, section->readonly); > if (ret) { > @@ -221,6 +232,7 @@ static void vhost_vdpa_listener_region_del(MemoryListener *listener, > > llsize = int128_sub(llend, int128_make64(iova)); > > + vhost_vdpa_iotlb_batch_begin_once(v); > ret = vhost_vdpa_dma_unmap(v, iova, int128_get64(llsize)); > if (ret) { > error_report("vhost_vdpa dma unmap error!"); > @@ -234,7 +246,6 @@ static void vhost_vdpa_listener_region_del(MemoryListener *listener, > * depends on the addnop(). > */ > static const MemoryListener vhost_vdpa_memory_listener = { > - .begin = vhost_vdpa_listener_begin, > .commit = vhost_vdpa_listener_commit, > .region_add = vhost_vdpa_listener_region_add, > .region_del = vhost_vdpa_listener_region_del, > -- > 2.27.0 >
On Mon, Aug 16, 2021 at 10:51:57AM +0800, Jason Wang wrote: > On Thu, Aug 12, 2021 at 10:09 PM Eugenio Pérez <eperezma@redhat.com> wrote: > > > > With the introduction of the batch hinting, meaningless batches can be > > created with no IOTLB updates if the memory region was skipped by > > vhost_vdpa_listener_skipped_section. This is the case of host notifiers > > memory regions, device un/realize, and others. This causes the vdpa > > device to receive dma mapping settings with no changes, a possibly > > expensive operation for nothing. > > > > To avoid that, VHOST_IOTLB_BATCH_BEGIN hint is delayed until we have a > > meaningful (not skipped section) mapping or unmapping operation, and > > VHOST_IOTLB_BATCH_END is not written unless at least one of _UPDATE / > > _INVALIDATE has been issued. > > Acked-by: Jason Wang <jasowang@redhat.com> Oops. You missed by pull request by a hairwidth. > > > > v3: > > * Use a bool instead of a counter avoiding potential number wrapping > > * Fix bad check on _commit > > * Move VHOST_BACKEND_F_IOTLB_BATCH check to > > vhost_vdpa_iotlb_batch_begin_once > > > > v2 (from RFC): > > * Rename misleading name > > * Abstract start batching function for listener_add/del > > > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com> > > --- > > include/hw/virtio/vhost-vdpa.h | 1 + > > hw/virtio/vhost-vdpa.c | 35 ++++++++++++++++++++++------------ > > 2 files changed, 24 insertions(+), 12 deletions(-) > > > > diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h > > index e98e327f12..6b9288fef8 100644 > > --- a/include/hw/virtio/vhost-vdpa.h > > +++ b/include/hw/virtio/vhost-vdpa.h > > @@ -23,6 +23,7 @@ typedef struct vhost_vdpa { > > int device_fd; > > int index; > > uint32_t msg_type; > > + bool iotlb_batch_begin_sent; > > MemoryListener listener; > > struct vhost_dev *dev; > > VhostVDPAHostNotifier notifier[VIRTIO_QUEUE_MAX]; > > diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c > > index 6ce94a1f4d..93b7db61d1 100644 > > --- a/hw/virtio/vhost-vdpa.c > > +++ b/hw/virtio/vhost-vdpa.c > > @@ -89,19 +89,13 @@ static int vhost_vdpa_dma_unmap(struct vhost_vdpa *v, hwaddr iova, > > return ret; > > } > > > > -static void vhost_vdpa_listener_begin(MemoryListener *listener) > > +static void vhost_vdpa_listener_begin_batch(struct vhost_vdpa *v) > > { > > - struct vhost_vdpa *v = container_of(listener, struct vhost_vdpa, listener); > > - struct vhost_dev *dev = v->dev; > > - struct vhost_msg_v2 msg = {}; > > int fd = v->device_fd; > > - > > - if (!(dev->backend_cap & (0x1ULL << VHOST_BACKEND_F_IOTLB_BATCH))) { > > - return; > > - } > > - > > - msg.type = v->msg_type; > > - msg.iotlb.type = VHOST_IOTLB_BATCH_BEGIN; > > + struct vhost_msg_v2 msg = { > > + .type = v->msg_type, > > + .iotlb.type = VHOST_IOTLB_BATCH_BEGIN, > > + }; > > > > if (write(fd, &msg, sizeof(msg)) != sizeof(msg)) { > > error_report("failed to write, fd=%d, errno=%d (%s)", > > @@ -109,6 +103,16 @@ static void vhost_vdpa_listener_begin(MemoryListener *listener) > > } > > } > > > > +static void vhost_vdpa_iotlb_batch_begin_once(struct vhost_vdpa *v) > > +{ > > + if (v->dev->backend_cap & (0x1ULL << VHOST_BACKEND_F_IOTLB_BATCH) && > > + !v->iotlb_batch_begin_sent) { > > + vhost_vdpa_listener_begin_batch(v); > > + } > > + > > + v->iotlb_batch_begin_sent = true; > > +} > > + > > static void vhost_vdpa_listener_commit(MemoryListener *listener) > > { > > struct vhost_vdpa *v = container_of(listener, struct vhost_vdpa, listener); > > @@ -120,6 +124,10 @@ static void vhost_vdpa_listener_commit(MemoryListener *listener) > > return; > > } > > > > + if (!v->iotlb_batch_begin_sent) { > > + return; > > + } > > + > > msg.type = v->msg_type; > > msg.iotlb.type = VHOST_IOTLB_BATCH_END; > > > > @@ -127,6 +135,8 @@ static void vhost_vdpa_listener_commit(MemoryListener *listener) > > error_report("failed to write, fd=%d, errno=%d (%s)", > > fd, errno, strerror(errno)); > > } > > + > > + v->iotlb_batch_begin_sent = false; > > } > > > > static void vhost_vdpa_listener_region_add(MemoryListener *listener, > > @@ -170,6 +180,7 @@ static void vhost_vdpa_listener_region_add(MemoryListener *listener, > > > > llsize = int128_sub(llend, int128_make64(iova)); > > > > + vhost_vdpa_iotlb_batch_begin_once(v); > > ret = vhost_vdpa_dma_map(v, iova, int128_get64(llsize), > > vaddr, section->readonly); > > if (ret) { > > @@ -221,6 +232,7 @@ static void vhost_vdpa_listener_region_del(MemoryListener *listener, > > > > llsize = int128_sub(llend, int128_make64(iova)); > > > > + vhost_vdpa_iotlb_batch_begin_once(v); > > ret = vhost_vdpa_dma_unmap(v, iova, int128_get64(llsize)); > > if (ret) { > > error_report("vhost_vdpa dma unmap error!"); > > @@ -234,7 +246,6 @@ static void vhost_vdpa_listener_region_del(MemoryListener *listener, > > * depends on the addnop(). > > */ > > static const MemoryListener vhost_vdpa_memory_listener = { > > - .begin = vhost_vdpa_listener_begin, > > .commit = vhost_vdpa_listener_commit, > > .region_add = vhost_vdpa_listener_region_add, > > .region_del = vhost_vdpa_listener_region_del, > > -- > > 2.27.0 > >
在 2021/8/16 下午1:36, Michael S. Tsirkin 写道: > On Mon, Aug 16, 2021 at 10:51:57AM +0800, Jason Wang wrote: >> On Thu, Aug 12, 2021 at 10:09 PM Eugenio Pérez<eperezma@redhat.com> wrote: >>> With the introduction of the batch hinting, meaningless batches can be >>> created with no IOTLB updates if the memory region was skipped by >>> vhost_vdpa_listener_skipped_section. This is the case of host notifiers >>> memory regions, device un/realize, and others. This causes the vdpa >>> device to receive dma mapping settings with no changes, a possibly >>> expensive operation for nothing. >>> >>> To avoid that, VHOST_IOTLB_BATCH_BEGIN hint is delayed until we have a >>> meaningful (not skipped section) mapping or unmapping operation, and >>> VHOST_IOTLB_BATCH_END is not written unless at least one of _UPDATE / >>> _INVALIDATE has been issued. >> Acked-by: Jason Wang<jasowang@redhat.com> > Oops. You missed by pull request by a hairwidth. It's fine. Thanks
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