Creates and supports a GPA->IOVA tree and a partial IOVA->HVA tree by
splitting up guest-backed memory maps and host-only memory maps from the
full IOVA->HVA tree. That is, any guest-backed memory maps are now
stored in the GPA->IOVA tree and host-only memory maps stay in the
IOVA->HVA tree.
Also propagates the GPAs (in_addr/out_addr) of a VirtQueueElement to
vhost_svq_translate_addr() to translate GPAs to IOVAs via the GPA->IOVA
tree (when descriptors are backed by guest memory). For descriptors
backed by host-only memory, the existing partial SVQ IOVA->HVA tree is
used.
GPAs are unique in the guest's address space, ensuring unambiguous IOVA
translations. This avoids the issue where different GPAs map to the same
HVA, causing the original HVA->IOVA translation to potentially return an
IOVA associated with the wrong intended GPA.
Signed-off-by: Jonah Palmer <jonah.palmer@oracle.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20250217144936.3589907-3-jonah.palmer@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
../hw/virtio/vhost-shadow-virtqueue.c:545:13: error: ‘r’ may be used uninitialized [-Werror=maybe-uninitialized]
Set `r` to 0 at every loop, since we don't check vhost_svq_get_buf()
return value.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Next patches in this series will delay the polling
and checking of buffers until either the SVQ is
full or control commands shadow buffers are full,
no longer perform an immediate poll and check of
the device's used buffers for each CVQ state load command.
To achieve this, this patch exposes
vhost_svq_available_slots(), allowing QEMU to know
whether the SVQ is full.
Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <25938079f0bd8185fd664c64e205e629f7a966be.1697165821.git.yin31149@gmail.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Next patches in this series will no longer perform an
immediate poll and check of the device's used buffers
for each CVQ state load command. Instead, they will
send CVQ state load commands in parallel by polling
multiple pending buffers at once.
To achieve this, this patch refactoring vhost_svq_poll()
to accept a new argument `num`, which allows vhost_svq_poll()
to wait for the device to use multiple elements,
rather than polling for a single element.
Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <950b3bfcfc5d446168b9d6a249d554a013a691d4.1693287885.git.yin31149@gmail.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
QEMU uses vhost_svq_translate_addr() to translate addresses
between the QEMU's virtual address and the SVQ IOVA. In order
to validate this translation, QEMU checks whether the translated
range falls within the mapped range.
Yet the problem is that, the value of `needle_last`, which is calculated
by `needle.translated_addr + iovec[i].iov_len`, should represent the
exclusive boundary of the translated range, rather than the last
inclusive addresses of the range. Consequently, QEMU fails the check
when the translated range matches the size of the mapped range.
This patch solves this problem by fixing the `needle_last` value to
the last inclusive address of the translated range.
Note that this bug cannot be triggered at the moment, because QEMU
is unable to translate such a big range due to the truncation of
the CVQ command in vhost_vdpa_net_handle_ctrl_avail().
Fixes: 34e3c94eda ("vdpa: Add custom IOTLB translations to SVQ")
Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
Message-Id: <ee31c5420ffc8e6a29705ddd30badb814ddbae1d.1688743107.git.yin31149@gmail.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The vdpa devices that use va addresses neeeds these maps shared.
Otherwise, vhost_vdpa checks will refuse to accept the maps.
The mmap call will always return a page aligned address, so removing the
qemu_memalign call. Keeping the ROUND_UP for the size as we still need
to DMA-map them in full.
Not applying fixes tag as it never worked with va devices.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20230602143854.1879091-4-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
QEMU invokes vhost_svq_add() when adding a guest's element
into SVQ. In vhost_svq_add(), it uses vhost_svq_available_slots()
to check whether QEMU can add the element into SVQ. If there is
enough space, then QEMU combines some out descriptors and some
in descriptors into one descriptor chain, and adds it into
`svq->vring.desc` by vhost_svq_vring_write_descs().
Yet the problem is that, `svq->shadow_avail_idx - svq->shadow_used_idx`
in vhost_svq_available_slots() returns the number of occupied elements,
or the number of descriptor chains, instead of the number of occupied
descriptors, which may cause wrapping in SVQ descriptor ring.
Here is an example. In vhost_handle_guest_kick(), QEMU forwards
as many available buffers to device by virtqueue_pop() and
vhost_svq_add_element(). virtqueue_pop() returns a guest's element,
and then this element is added into SVQ by vhost_svq_add_element(),
a wrapper to vhost_svq_add(). If QEMU invokes virtqueue_pop() and
vhost_svq_add_element() `svq->vring.num` times,
vhost_svq_available_slots() thinks QEMU just ran out of slots and
everything should work fine. But in fact, virtqueue_pop() returns
`svq->vring.num` elements or descriptor chains, more than
`svq->vring.num` descriptors due to guest memory fragmentation,
and this causes wrapping in SVQ descriptor ring.
This bug is valid even before marking the descriptors used.
If the guest memory is fragmented, SVQ must add chains
so it can try to add more descriptors than possible.
This patch solves it by adding `num_free` field in
VhostShadowVirtqueue structure and updating this field
in vhost_svq_add() and vhost_svq_get_buf(), to record
the number of free descriptors.
Fixes: 100890f7ca ("vhost: Shadow virtqueue buffers forwarding")
Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20230509084817.3973-1-yin31149@gmail.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
At this moment it is only possible to migrate to a vdpa device running
with x-svq=on. As a protective measure, the rewind of the inflight
descriptors was done at the destination. That way if the source sent a
virtqueue with inuse descriptors they are always discarded.
Since this series allows to migrate also to passthrough devices with no
SVQ, the right thing to do is to rewind at the source so the base of
vrings are correct.
Support for inflight descriptors may be added in the future.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230303172445.1089785-5-eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
In vhost_svq_poll(), if vhost_svq_get_buf() fails due to a device
providing invalid descriptors, len is left uninitialized and returned
to the caller, potentally leaking stack data or causing undefined
behavior.
Fix this by initializing len to 0.
Found with GCC 13 and -fanalyzer (abridged):
../hw/virtio/vhost-shadow-virtqueue.c: In function ‘vhost_svq_poll’:
../hw/virtio/vhost-shadow-virtqueue.c:538:12: warning: use of uninitialized value ‘len’ [CWE-457] [-Wanalyzer-use-of-uninitialized-value]
538 | return len;
| ^~~
‘vhost_svq_poll’: events 1-4
|
| 522 | size_t vhost_svq_poll(VhostShadowVirtqueue *svq)
| | ^~~~~~~~~~~~~~
| | |
| | (1) entry to ‘vhost_svq_poll’
|......
| 525 | uint32_t len;
| | ~~~
| | |
| | (2) region created on stack here
| | (3) capacity: 4 bytes
|......
| 528 | if (vhost_svq_more_used(svq)) {
| | ~
| | |
| | (4) inlined call to ‘vhost_svq_more_used’ from ‘vhost_svq_poll’
(...)
| 528 | if (vhost_svq_more_used(svq)) {
| | ^~~~~~~~~~~~~~~~~~~~~~~~~
| | ||
| | |(8) ...to here
| | (7) following ‘true’ branch...
|......
| 537 | vhost_svq_get_buf(svq, &len);
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | (9) calling ‘vhost_svq_get_buf’ from ‘vhost_svq_poll’
|
+--> ‘vhost_svq_get_buf’: events 10-11
|
| 416 | static VirtQueueElement *vhost_svq_get_buf(VhostShadowVirtqueue *svq,
| | ^~~~~~~~~~~~~~~~~
| | |
| | (10) entry to ‘vhost_svq_get_buf’
|......
| 423 | if (!vhost_svq_more_used(svq)) {
| | ~
| | |
| | (11) inlined call to ‘vhost_svq_more_used’ from ‘vhost_svq_get_buf’
|
(...)
|
‘vhost_svq_get_buf’: event 14
|
| 423 | if (!vhost_svq_more_used(svq)) {
| | ^
| | |
| | (14) following ‘false’ branch...
|
‘vhost_svq_get_buf’: event 15
|
|cc1:
| (15): ...to here
|
<------+
|
‘vhost_svq_poll’: events 16-17
|
| 537 | vhost_svq_get_buf(svq, &len);
| | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | (16) returning to ‘vhost_svq_poll’ from ‘vhost_svq_get_buf’
| 538 | return len;
| | ~~~
| | |
| | (17) use of uninitialized value ‘len’ here
Note by Laurent Vivier <lvivier@redhat.com>:
The return value is only used to detect an error:
vhost_svq_poll
vhost_vdpa_net_cvq_add
vhost_vdpa_net_load_cmd
vhost_vdpa_net_load_mac
-> a negative return is only used to detect error
vhost_vdpa_net_load_mq
-> a negative return is only used to detect error
vhost_vdpa_net_handle_ctrl_avail
-> a negative return is only used to detect error
Fixes: d368c0b052 ("vhost: Do not depend on !NULL VirtQueueElement on vhost_svq_flush")
Signed-off-by: Carlos López <clopez@suse.de>
Message-Id: <20230213085747.19956-1-clopez@suse.de>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Since we don't know if we will use SVQ at qemu initialization, let's
allocate iova_tree only if needed. To do so, accept it at SVQ start, not
at initialization.
This will avoid to create it if the device does not support SVQ.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20221215113144.322011-5-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The next patches will start control SVQ if possible. However, we don't
know if that will be possible at qemu boot anymore.
Delay device file descriptors until we know it at device start. This
will avoid to create them if the device does not support SVQ.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20221215113144.322011-4-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
By the end of this series CVQ is shadowed as long as the features
support it.
Since we don't know at the beginning of qemu running if this is
supported, move the event notifier handler setting to the start of the
SVQ, instead of the start of qemu run. This will avoid to create them if
the device does not support SVQ.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20221215113144.322011-3-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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>
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>
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: 9c2ab2f1ec ("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>
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>
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>
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>
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>
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>
