linux.git/drivers/vhost/vringh.c, branch v6.7

vringh: don't use vringh_kiov_advance() in vringh_iov_xfer()

2023-10-04T07:26:48+00:00

In the while loop of vringh_iov_xfer(), `partlen` could be 0 if one of
the `iov` has 0 lenght.
In this case, we should skip the iov and go to the next one.
But calling vringh_kiov_advance() with 0 lenght does not cause the
advancement, since it returns immediately if asked to advance by 0 bytes.

Let's restore the code that was there before commit b8c06ad4d67d
("vringh: implement vringh_kiov_advance()"), avoiding using
vringh_kiov_advance().

Fixes: b8c06ad4d67d ("vringh: implement vringh_kiov_advance()")
Cc: stable@vger.kernel.org
Reported-by: Jason Wang 
Signed-off-by: Stefano Garzarella 
Acked-by: Jason Wang 
Signed-off-by: David S. Miller

vringh: support VA with iotlb

2023-04-21T07:02:33+00:00

vDPA supports the possibility to use user VA in the iotlb messages.
So, let's add support for user VA in vringh to use it in the vDPA
simulators.

Acked-by: Eugenio Pérez 
Signed-off-by: Stefano Garzarella 
Message-Id: <20230404131716.45855-1-sgarzare@redhat.com>
Signed-off-by: Michael S. Tsirkin

vringh: define the stride used for translation

2023-04-21T07:02:33+00:00

Define a macro to be reused in the different parts of the code.

Useful for the next patches where we add more arrays to manage also
translations with user VA.

Suggested-by: Eugenio Perez Martin 
Signed-off-by: Stefano Garzarella 
Message-Id: <20230404131326.44403-5-sgarzare@redhat.com>
Signed-off-by: Michael S. Tsirkin

vringh: replace kmap_atomic() with kmap_local_page()

2023-04-21T07:02:33+00:00

kmap_atomic() is deprecated in favor of kmap_local_page() since commit
f3ba3c710ac5 ("mm/highmem: Provide kmap_local*").

With kmap_local_page() the mappings are per thread, CPU local, can take
page-faults, and can be called from any context (including interrupts).
Furthermore, the tasks can be preempted and, when they are scheduled to
run again, the kernel virtual addresses are restored and still valid.

kmap_atomic() is implemented like a kmap_local_page() which also disables
page-faults and preemption (the latter only for !PREEMPT_RT kernels,
otherwise it only disables migration).

The code within the mappings/un-mappings in getu16_iotlb() and
putu16_iotlb() don't depend on the above-mentioned side effects of
kmap_atomic(), so that mere replacements of the old API with the new one
is all that is required (i.e., there is no need to explicitly add calls
to pagefault_disable() and/or preempt_disable()).

This commit reuses a "boiler plate" commit message from Fabio, who has
already did this change in several places.

Cc: "Fabio M. De Francesco" 
Reviewed-by: Fabio M. De Francesco 
Acked-by: Jason Wang 
Signed-off-by: Stefano Garzarella 
Message-Id: <20230404131326.44403-4-sgarzare@redhat.com>
Signed-off-by: Michael S. Tsirkin

vringh: fix typos in the vringh_init_* documentation

2023-04-21T07:02:32+00:00

Replace `userpace` with `userspace`.

Cc: Simon Horman 
Signed-off-by: Stefano Garzarella 
Message-Id: <20230331080208.17002-1-sgarzare@redhat.com>
Signed-off-by: Michael S. Tsirkin 
Reviewed-by: Xuan Zhuo 
Acked-by: Jason Wang

vringh: use bvec_set_page to initialize a bvec

2023-02-03T17:17:42+00:00

Use the bvec_set_page helper to initialize a bvec.

Signed-off-by: Christoph Hellwig 
Acked-by: Jason Wang 
Link: https://lore.kernel.org/r/20230203150634.3199647-23-hch@lst.de
Signed-off-by: Jens Axboe

vringh: fix range used in iotlb_translate()

2022-12-28T10:28:10+00:00

vhost_iotlb_itree_first() requires `start` and `last` parameters
to search for a mapping that overlaps the range.

In iotlb_translate() we cyclically call vhost_iotlb_itree_first(),
incrementing `addr` by the amount already translated, so rightly
we move the `start` parameter passed to vhost_iotlb_itree_first(),
but we should hold the `last` parameter constant.

Let's fix it by saving the `last` parameter value before incrementing
`addr` in the loop.

Fixes: 9ad9c49cfe97 ("vringh: IOTLB support")
Acked-by: Jason Wang 
Signed-off-by: Stefano Garzarella 
Message-Id: <20221109102503.18816-2-sgarzare@redhat.com>
Signed-off-by: Michael S. Tsirkin

use less confusing names for iov_iter direction initializers

2022-11-25T18:01:55+00:00

READ/WRITE proved to be actively confusing - the meanings are
"data destination, as used with read(2)" and "data source, as
used with write(2)", but people keep interpreting those as
"we read data from it" and "we write data to it", i.e. exactly
the wrong way.

Call them ITER_DEST and ITER_SOURCE - at least that is harder
to misinterpret...

Signed-off-by: Al Viro

[vhost] fix 'direction' argument of iov_iter_{init,bvec}()

2022-11-25T18:01:21+00:00

READ means "data destination", WRITE - "data source".

Signed-off-by: Al Viro

vringh: iterate on iotlb_translate to handle large translations

2022-08-11T08:06:37+00:00

iotlb_translate() can return -ENOBUFS if the bio_vec is not big enough
to contain all the ranges for translation.
This can happen for example if the VMM maps a large bounce buffer,
without using hugepages, that requires more than 16 ranges to translate
the addresses.

To handle this case, let's extend iotlb_translate() to also return the
number of bytes successfully translated.
In copy_from_iotlb()/copy_to_iotlb() loops by calling iotlb_translate()
several times until we complete the translation.

Signed-off-by: Stefano Garzarella 
Message-Id: <20220624075656.13997-1-sgarzare@redhat.com>
Signed-off-by: Michael S. Tsirkin