| Message ID | 20200410034143.24738.78852.stgit@localhost.localdomain |
|---|---|
| State | New |
| Headers | show |
| Series | virtio-balloon: add support for free page reporting | expand |
On 10.04.20 05:41, Alexander Duyck wrote: > From: Alexander Duyck <alexander.h.duyck@linux.intel.com> > > Add support for free page reporting. The idea is to function very similar > to how the balloon works in that we basically end up madvising the page as > not being used. However we don't really need to bother with any deflate > type logic since the page will be faulted back into the guest when it is > read or written to. > > This provides a new way of letting the guest proactively report free > pages to the hypervisor, so the hypervisor can reuse them. In contrast to > inflate/deflate that is triggered via the hypervisor explicitly. Much better, thanks! > > Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> > --- > hw/virtio/virtio-balloon.c | 63 +++++++++++++++++++++++++++++++++++- > include/hw/virtio/virtio-balloon.h | 2 + > 2 files changed, 62 insertions(+), 3 deletions(-) > > diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c > index 1c6d36a29a04..86d8b48a8e3a 100644 > --- a/hw/virtio/virtio-balloon.c > +++ b/hw/virtio/virtio-balloon.c > @@ -321,6 +321,57 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v, > balloon_stats_change_timer(s, 0); > } > > +static void virtio_balloon_handle_report(VirtIODevice *vdev, VirtQueue *vq) > +{ > + VirtIOBalloon *dev = VIRTIO_BALLOON(vdev); > + VirtQueueElement *elem; > + > + while ((elem = virtqueue_pop(vq, sizeof(VirtQueueElement)))) { > + unsigned int i; > + > + for (i = 0; i < elem->in_num; i++) { > + void *addr = elem->in_sg[i].iov_base; > + size_t size = elem->in_sg[i].iov_len; > + ram_addr_t ram_offset; > + size_t rb_page_size; > + RAMBlock *rb; > + > + if (qemu_balloon_is_inhibited() || dev->poison_val) { > + continue; actually, you want to do that in the outer loop, no? > + } > + > + /* > + * There is no need to check the memory section to see if > + * it is ram/readonly/romd like there is for handle_output > + * below. If the region is not meant to be written to then > + * address_space_map will have allocated a bounce buffer > + * and it will be freed in address_space_unmap and trigger > + * and unassigned_mem_write before failing to copy over the > + * buffer. If more than one bad descriptor is provided it > + * will return NULL after the first bounce buffer and fail > + * to map any resources. > + */ > + rb = qemu_ram_block_from_host(addr, false, &ram_offset); > + if (!rb) { > + trace_virtio_balloon_bad_addr(elem->in_addr[i]); > + continue; > + } > + > + /* For now we will simply ignore unaligned memory regions */ > + rb_page_size = qemu_ram_pagesize(rb); > + if (!QEMU_IS_ALIGNED(ram_offset | size, rb_page_size)) { /me thinks you can drop rb_page_size I *think* there is still one remaining case to handle: Crossing RAM blocks. Most probably you should check /* For now, ignore crossing RAM blocks. */ if (ram_offset + size >= qemu_ram_get_used_length()) { continue; } otherwise ram_block_discard_range() will report an error.
On 15.04.20 10:17, David Hildenbrand wrote: > On 10.04.20 05:41, Alexander Duyck wrote: >> From: Alexander Duyck <alexander.h.duyck@linux.intel.com> >> >> Add support for free page reporting. The idea is to function very similar >> to how the balloon works in that we basically end up madvising the page as >> not being used. However we don't really need to bother with any deflate >> type logic since the page will be faulted back into the guest when it is >> read or written to. >> >> This provides a new way of letting the guest proactively report free >> pages to the hypervisor, so the hypervisor can reuse them. In contrast to >> inflate/deflate that is triggered via the hypervisor explicitly. > > Much better, thanks! > >> >> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> >> --- >> hw/virtio/virtio-balloon.c | 63 +++++++++++++++++++++++++++++++++++- >> include/hw/virtio/virtio-balloon.h | 2 + >> 2 files changed, 62 insertions(+), 3 deletions(-) >> >> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c >> index 1c6d36a29a04..86d8b48a8e3a 100644 >> --- a/hw/virtio/virtio-balloon.c >> +++ b/hw/virtio/virtio-balloon.c >> @@ -321,6 +321,57 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v, >> balloon_stats_change_timer(s, 0); >> } >> >> +static void virtio_balloon_handle_report(VirtIODevice *vdev, VirtQueue *vq) >> +{ >> + VirtIOBalloon *dev = VIRTIO_BALLOON(vdev); >> + VirtQueueElement *elem; >> + >> + while ((elem = virtqueue_pop(vq, sizeof(VirtQueueElement)))) { >> + unsigned int i; >> + >> + for (i = 0; i < elem->in_num; i++) { >> + void *addr = elem->in_sg[i].iov_base; >> + size_t size = elem->in_sg[i].iov_len; >> + ram_addr_t ram_offset; >> + size_t rb_page_size; >> + RAMBlock *rb; >> + >> + if (qemu_balloon_is_inhibited() || dev->poison_val) { >> + continue; > > actually, you want to do that in the outer loop, no? > >> + } >> + >> + /* >> + * There is no need to check the memory section to see if >> + * it is ram/readonly/romd like there is for handle_output >> + * below. If the region is not meant to be written to then >> + * address_space_map will have allocated a bounce buffer >> + * and it will be freed in address_space_unmap and trigger >> + * and unassigned_mem_write before failing to copy over the >> + * buffer. If more than one bad descriptor is provided it >> + * will return NULL after the first bounce buffer and fail >> + * to map any resources. >> + */ >> + rb = qemu_ram_block_from_host(addr, false, &ram_offset); >> + if (!rb) { >> + trace_virtio_balloon_bad_addr(elem->in_addr[i]); >> + continue; >> + } >> + >> + /* For now we will simply ignore unaligned memory regions */ >> + rb_page_size = qemu_ram_pagesize(rb); >> + if (!QEMU_IS_ALIGNED(ram_offset | size, rb_page_size)) { > > /me thinks you can drop rb_page_size > > I *think* there is still one remaining case to handle: Crossing RAM blocks. > > Most probably you should check > > /* For now, ignore crossing RAM blocks. */ > if (ram_offset + size >= qemu_ram_get_used_length()) { > continue; (should be an > I guess)
On Wed, Apr 15, 2020 at 1:17 AM David Hildenbrand <david@redhat.com> wrote: > > On 10.04.20 05:41, Alexander Duyck wrote: > > From: Alexander Duyck <alexander.h.duyck@linux.intel.com> > > > > Add support for free page reporting. The idea is to function very similar > > to how the balloon works in that we basically end up madvising the page as > > not being used. However we don't really need to bother with any deflate > > type logic since the page will be faulted back into the guest when it is > > read or written to. > > > > This provides a new way of letting the guest proactively report free > > pages to the hypervisor, so the hypervisor can reuse them. In contrast to > > inflate/deflate that is triggered via the hypervisor explicitly. > > Much better, thanks! > > > > > Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> > > --- > > hw/virtio/virtio-balloon.c | 63 +++++++++++++++++++++++++++++++++++- > > include/hw/virtio/virtio-balloon.h | 2 + > > 2 files changed, 62 insertions(+), 3 deletions(-) > > > > diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c > > index 1c6d36a29a04..86d8b48a8e3a 100644 > > --- a/hw/virtio/virtio-balloon.c > > +++ b/hw/virtio/virtio-balloon.c > > @@ -321,6 +321,57 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v, > > balloon_stats_change_timer(s, 0); > > } > > > > +static void virtio_balloon_handle_report(VirtIODevice *vdev, VirtQueue *vq) > > +{ > > + VirtIOBalloon *dev = VIRTIO_BALLOON(vdev); > > + VirtQueueElement *elem; > > + > > + while ((elem = virtqueue_pop(vq, sizeof(VirtQueueElement)))) { > > + unsigned int i; > > + > > + for (i = 0; i < elem->in_num; i++) { > > + void *addr = elem->in_sg[i].iov_base; > > + size_t size = elem->in_sg[i].iov_len; > > + ram_addr_t ram_offset; > > + size_t rb_page_size; > > + RAMBlock *rb; > > + > > + if (qemu_balloon_is_inhibited() || dev->poison_val) { > > + continue; > > actually, you want to do that in the outer loop, no? I'll move that. Odds are compiler was doing that anyway. > > + } > > + > > + /* > > + * There is no need to check the memory section to see if > > + * it is ram/readonly/romd like there is for handle_output > > + * below. If the region is not meant to be written to then > > + * address_space_map will have allocated a bounce buffer > > + * and it will be freed in address_space_unmap and trigger > > + * and unassigned_mem_write before failing to copy over the > > + * buffer. If more than one bad descriptor is provided it > > + * will return NULL after the first bounce buffer and fail > > + * to map any resources. > > + */ > > + rb = qemu_ram_block_from_host(addr, false, &ram_offset); > > + if (!rb) { > > + trace_virtio_balloon_bad_addr(elem->in_addr[i]); > > + continue; > > + } > > + > > + /* For now we will simply ignore unaligned memory regions */ > > + rb_page_size = qemu_ram_pagesize(rb); > > + if (!QEMU_IS_ALIGNED(ram_offset | size, rb_page_size)) { > > /me thinks you can drop rb_page_size You mean just fold it into the statement? I guess I can do that. > I *think* there is still one remaining case to handle: Crossing RAM blocks. > > Most probably you should check > > /* For now, ignore crossing RAM blocks. */ > if (ram_offset + size >= qemu_ram_get_used_length()) { > continue; > } > > otherwise ram_block_discard_range() will report an error. Makes sense. I can add that into the QEMU_IS_ALIGNED check.
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index 1c6d36a29a04..86d8b48a8e3a 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -321,6 +321,57 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v, balloon_stats_change_timer(s, 0); } +static void virtio_balloon_handle_report(VirtIODevice *vdev, VirtQueue *vq) +{ + VirtIOBalloon *dev = VIRTIO_BALLOON(vdev); + VirtQueueElement *elem; + + while ((elem = virtqueue_pop(vq, sizeof(VirtQueueElement)))) { + unsigned int i; + + for (i = 0; i < elem->in_num; i++) { + void *addr = elem->in_sg[i].iov_base; + size_t size = elem->in_sg[i].iov_len; + ram_addr_t ram_offset; + size_t rb_page_size; + RAMBlock *rb; + + if (qemu_balloon_is_inhibited() || dev->poison_val) { + continue; + } + + /* + * There is no need to check the memory section to see if + * it is ram/readonly/romd like there is for handle_output + * below. If the region is not meant to be written to then + * address_space_map will have allocated a bounce buffer + * and it will be freed in address_space_unmap and trigger + * and unassigned_mem_write before failing to copy over the + * buffer. If more than one bad descriptor is provided it + * will return NULL after the first bounce buffer and fail + * to map any resources. + */ + rb = qemu_ram_block_from_host(addr, false, &ram_offset); + if (!rb) { + trace_virtio_balloon_bad_addr(elem->in_addr[i]); + continue; + } + + /* For now we will simply ignore unaligned memory regions */ + rb_page_size = qemu_ram_pagesize(rb); + if (!QEMU_IS_ALIGNED(ram_offset | size, rb_page_size)) { + continue; + } + + ram_block_discard_range(rb, ram_offset, size); + } + + virtqueue_push(vq, elem, 0); + virtio_notify(vdev, vq); + g_free(elem); + } +} + static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq) { VirtIOBalloon *s = VIRTIO_BALLOON(vdev); @@ -628,7 +679,8 @@ static size_t virtio_balloon_config_size(VirtIOBalloon *s) return sizeof(struct virtio_balloon_config); } if (virtio_has_feature(features, VIRTIO_BALLOON_F_PAGE_POISON) || - virtio_has_feature(features, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { + virtio_has_feature(features, VIRTIO_BALLOON_F_FREE_PAGE_HINT) || + virtio_has_feature(features, VIRTIO_BALLOON_F_REPORTING)) { return sizeof(struct virtio_balloon_config); } return offsetof(struct virtio_balloon_config, free_page_report_cmd_id); @@ -717,7 +769,8 @@ static uint64_t virtio_balloon_get_features(VirtIODevice *vdev, uint64_t f, VirtIOBalloon *dev = VIRTIO_BALLOON(vdev); f |= dev->host_features; virtio_add_feature(&f, VIRTIO_BALLOON_F_STATS_VQ); - if (virtio_has_feature(f, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { + if (virtio_has_feature(f, VIRTIO_BALLOON_F_FREE_PAGE_HINT) || + virtio_has_feature(f, VIRTIO_BALLOON_F_REPORTING)) { virtio_add_feature(&f, VIRTIO_BALLOON_F_PAGE_POISON); } @@ -807,6 +860,10 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp) s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output); s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats); + if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_REPORTING)) { + s->rvq = virtio_add_queue(vdev, 32, virtio_balloon_handle_report); + } + if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { s->free_page_vq = virtio_add_queue(vdev, VIRTQUEUE_MAX_SIZE, @@ -940,6 +997,8 @@ static Property virtio_balloon_properties[] = { */ DEFINE_PROP_BOOL("qemu-4-0-config-size", VirtIOBalloon, qemu_4_0_config_size, false), + DEFINE_PROP_BIT("free-page-reporting", VirtIOBalloon, host_features, + VIRTIO_BALLOON_F_REPORTING, true), DEFINE_PROP_LINK("iothread", VirtIOBalloon, iothread, TYPE_IOTHREAD, IOThread *), DEFINE_PROP_END_OF_LIST(), diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h index 7fe78e5c14d7..db5bf7127112 100644 --- a/include/hw/virtio/virtio-balloon.h +++ b/include/hw/virtio/virtio-balloon.h @@ -42,7 +42,7 @@ enum virtio_balloon_free_page_report_status { typedef struct VirtIOBalloon { VirtIODevice parent_obj; - VirtQueue *ivq, *dvq, *svq, *free_page_vq; + VirtQueue *ivq, *dvq, *svq, *free_page_vq, *rvq; uint32_t free_page_report_status; uint32_t num_pages; uint32_t actual;