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path: root/hw/virtio/vhost-shadow-virtqueue.c
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2022-10-28vhost: Accept event idx flagEugenio Pérez1-0/+1
Enabling all the code path created before. Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-10-28vhost: use avail event idx on vhost_svq_kickEugenio Pérez1-1/+11
So SVQ code knows if an event is needed. The code is not reachable at the moment. Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-10-28vhost: toggle device callbacks using used event idxEugenio Pérez1-3/+15
Actually use the new field of the used ring and tell the device if SVQ wants to be notified. The code is not reachable at the moment. Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-10-28vhost: allocate event_idx fields on vringEugenio Pérez1-4/+4
There was not enough room to accomodate them. Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-09-29hw/virtio/vhost-shadow-virtqueue: Silence GCC error "maybe-uninitialized"Bernhard Beschow1-1/+1
GCC issues a false positive warning, resulting in build failure with -Werror: In file included from /usr/include/glib-2.0/glib.h:114, from src/include/glib-compat.h:32, from src/include/qemu/osdep.h:144, from ../src/hw/virtio/vhost-shadow-virtqueue.c:10: In function ‘g_autoptr_cleanup_generic_gfree’, inlined from ‘vhost_handle_guest_kick’ at ../src/hw/virtio/vhost-shadow-virtqueue.c:292:42: /usr/include/glib-2.0/glib/glib-autocleanups.h:28:3: error: ‘elem’ may be used uninitialized [-Werror=maybe-uninitialized] 28 | g_free (*pp); | ^~~~~~~~~~~~ ../src/hw/virtio/vhost-shadow-virtqueue.c: In function ‘vhost_handle_guest_kick’: ../src/hw/virtio/vhost-shadow-virtqueue.c:292:42: note: ‘elem’ was declared here 292 | g_autofree VirtQueueElement *elem; | ^~~~ cc1: all warnings being treated as errors There is actually no problem since "elem" is initialized in both branches. Silence the warning by initializig it with "NULL". $ gcc --version gcc (GCC) 12.2.0 Fixes: 9c2ab2f1ec333be8614cc12272d4b91960704dbe ("vhost: stop transfer elem ownership in vhost_handle_guest_kick") Signed-off-by: Bernhard Beschow <shentey@gmail.com> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Message-Id: <20220910151117.6665-1-shentey@gmail.com> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
2022-09-02vhost: Do not depend on !NULL VirtQueueElement on vhost_svq_flushEugenio Pérez1-4/+7
Since QEMU will be able to inject new elements on CVQ to restore the state, we need not to depend on a VirtQueueElement to know if a new element has been used by the device or not. Instead of check that, check if there are new elements only using used idx on vhost_svq_flush. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Acked-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-09-02vhost: Delete useless read memory barrierEugenio Pérez1-3/+0
As discussed in previous series [1], this memory barrier is useless with the atomic read of used idx at vhost_svq_more_used. Deleting it. [1] https://lists.nongnu.org/archive/html/qemu-devel/2022-07/msg02616.html Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Acked-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-09-02vhost: use SVQ element ndescs instead of opaque data for desc validationEugenio Pérez1-1/+2
Since we're going to allow SVQ to add elements without the guest's knowledge and without its own VirtQueueElement, it's easier to check if an element is a valid head checking a different thing than the VirtQueueElement. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Acked-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-09-02vhost: stop transfer elem ownership in vhost_handle_guest_kickEugenio Pérez1-6/+4
It was easier to allow vhost_svq_add to handle the memory. Now that we will allow qemu to add elements to a SVQ without the guest's knowledge, it's better to handle it in the caller. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Acked-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-09-02vhost: Always store new kick fd on vhost_svq_set_svq_kick_fdEugenio Pérez1-2/+2
We can unbind twice a file descriptor if we call twice vhost_svq_set_svq_kick_fd because of this. Since it comes from vhost and not from SVQ, that file descriptor could be a different thing that guest's vhost notifier. Likewise, it can happens the same if a guest start and stop the device multiple times. Reported-by: Lei Yang <leiyang@redhat.com> Fixes: dff4426fa6 ("vhost: Add Shadow VirtQueue kick forwarding capabilities") Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Acked-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-07-20vhost: Add svq avail_handler callbackEugenio Pérez1-2/+12
This allows external handlers to be aware of new buffers that the guest places in the virtqueue. When this callback is defined the ownership of the guest's virtqueue element is transferred to the callback. This means that if the user wants to forward the descriptor it needs to manually inject it. The callback is also free to process the command by itself and use the element with svq_push. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-07-20vhost: add vhost_svq_pollEugenio Pérez1-0/+27
It allows the Shadow Control VirtQueue to wait for the device to use the available buffers. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-07-20vhost: Expose vhost_svq_addEugenio Pérez1-3/+3
This allows external parts of SVQ to forward custom buffers to the device. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-07-20vhost: add vhost_svq_push_elemEugenio Pérez1-0/+16
This function allows external SVQ users to return guest's available buffers. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-07-20vhost: Track number of descs in SVQDescStateEugenio Pérez1-2/+2
A guest's buffer continuos on GPA may need multiple descriptors on qemu's VA, so SVQ should track its length sepparatedly. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-07-20vhost: Add SVQDescStateEugenio Pérez1-8/+8
This will allow SVQ to add context to the different queue elements. This patch only store the actual element, no functional change intended. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-07-20vhost: Decouple vhost_svq_add from VirtQueueElementEugenio Pérez1-11/+22
VirtQueueElement comes from the guest, but we're heading SVQ to be able to modify the element presented to the device without the guest's knowledge. To do so, make SVQ accept sg buffers directly, instead of using VirtQueueElement. Add vhost_svq_add_element to maintain element convenience. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Acked-by: Jason Wang <jasowang@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-07-20vhost: Check for queue full at vhost_svq_addEugenio Pérez1-26/+33
The series need to expose vhost_svq_add with full functionality, including checking for full queue. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-07-20vhost: Move vhost_svq_kick call to vhost_svq_addEugenio Pérez1-1/+1
The series needs to expose vhost_svq_add with full functionality, including kick Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-07-20vhost: Reorder vhost_svq_kickEugenio Pérez1-14/+14
Future code needs to call it from vhost_svq_add. No functional change intended. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-07-20vdpa: Avoid compiler to squash reads to used idxEugenio Pérez1-1/+2
In the next patch we will allow busypolling of this value. The compiler have a running path where shadow_used_idx, last_used_idx, and vring used idx are not modified within the same thread busypolling. This was not an issue before since we always cleared device event notifier before checking it, and that could act as memory barrier. However, the busypoll needs something similar to kernel READ_ONCE. Let's add it here, sepparated from the polling. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-07-20vhost: move descriptor translation to vhost_svq_vring_write_descsEugenio Pérez1-11/+27
It's done for both in and out descriptors so it's better placed here. Acked-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-05-13vhost: Fix element in vhost_svq_add failureEugenio Pérez1-0/+8
Coverity rightly reports that is not free in that case. Fixes: Coverity CID 1487559 Fixes: 100890f7ca ("vhost: Shadow virtqueue buffers forwarding") Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Message-Id: <20220512175747.142058-7-eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2022-05-13vhost: Fix device's used descriptor dequeueEugenio Pérez1-2/+15
Only the first one of them were properly enqueued back. Fixes: 100890f7ca ("vhost: Shadow virtqueue buffers forwarding") Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Message-Id: <20220512175747.142058-3-eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2022-05-13vhost: Track descriptor chain in private at SVQEugenio Pérez1-5/+7
The device could have access to modify them, and it definitely have access when we implement packed vq. Harden SVQ maintaining a private copy of the descriptor chain. Other fields like buffer addresses are already maintained sepparatedly. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Message-Id: <20220512175747.142058-2-eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2022-04-06Replace qemu_real_host_page variables with inlined functionsMarc-André Lureau1-4/+4
Replace the global variables with inlined helper functions. getpagesize() is very likely annotated with a "const" function attribute (at least with glibc), and thus optimization should apply even better. This avoids the need for a constructor initialization too. Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Message-Id: <20220323155743.1585078-12-marcandre.lureau@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-03-15vdpa: Add custom IOTLB translations to SVQEugenio Pérez1-9/+77
Use translations added in VhostIOVATree in SVQ. Only introduce usage here, not allocation and deallocation. As with previous patches, we use the dead code paths of shadow_vqs_enabled to avoid commiting too many changes at once. These are impossible to take at the moment. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-03-15vhost: Shadow virtqueue buffers forwardingEugenio Pérez1-6/+346
Initial version of shadow virtqueue that actually forward buffers. There is no iommu support at the moment, and that will be addressed in future patches of this series. Since all vhost-vdpa devices use forced IOMMU, this means that SVQ is not usable at this point of the series on any device. For simplicity it only supports modern devices, that expects vring in little endian, with split ring and no event idx or indirect descriptors. Support for them will not be added in this series. It reuses the VirtQueue code for the device part. The driver part is based on Linux's virtio_ring driver, but with stripped functionality and optimizations so it's easier to review. However, forwarding buffers have some particular pieces: One of the most unexpected ones is that a guest's buffer can expand through more than one descriptor in SVQ. While this is handled gracefully by qemu's emulated virtio devices, it may cause unexpected SVQ queue full. This patch also solves it by checking for this condition at both guest's kicks and device's calls. The code may be more elegant in the future if SVQ code runs in its own iocontext. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-03-15virtio: Add vhost_svq_get_vring_addrEugenio Pérez1-0/+29
It reports the shadow virtqueue address from qemu virtual address space. Since this will be different from the guest's vaddr, but the device can access it, SVQ takes special care about its alignment & lack of garbage data. It assumes that IOMMU will work in host_page_size ranges for that. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-03-15vhost: Add vhost_svq_valid_features to shadow vqEugenio Pérez1-0/+44
This allows SVQ to negotiate features with the guest and the device. For the device, SVQ is a driver. While this function bypasses all non-transport features, it needs to disable the features that SVQ does not support when forwarding buffers. This includes packed vq layout, indirect descriptors or event idx. Future changes can add support to offer more features to the guest, since the use of VirtQueue gives this for free. This is left out at the moment for simplicity. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-03-15vhost: Add Shadow VirtQueue call forwarding capabilitiesEugenio Pérez1-0/+38
This will make qemu aware of the device used buffers, allowing it to write the guest memory with its contents if needed. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-03-15vhost: Add Shadow VirtQueue kick forwarding capabilitiesEugenio Pérez1-0/+55
At this mode no buffer forwarding will be performed in SVQ mode: Qemu will just forward the guest's kicks to the device. Host memory notifiers regions are left out for simplicity, and they will not be addressed in this series. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2022-03-15vhost: Add VhostShadowVirtqueueEugenio Pérez1-0/+62
Vhost shadow virtqueue (SVQ) is an intermediate jump for virtqueue notifications and buffers, allowing qemu to track them. While qemu is forwarding the buffers and virtqueue changes, it is able to commit the memory it's being dirtied, the same way regular qemu's VirtIO devices do. This commit only exposes basic SVQ allocation and free. Next patches of the series add functionality like notifications and buffers forwarding. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
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