kernel.git/drivers/vhost/vringh.c, branch linux-5.18.y

vringh: Fix loop descriptors check in the indirect cases

2022-06-14T16:45:15Z

[ Upstream commit dbd29e0752286af74243cf891accf472b2f3edd8 ] We should use size of descriptor chain to test loop condition in the indirect case. And another statistical count is also introduced for indirect descriptors to avoid conflict with the statistical count of direct descriptors. Fixes: f87d0fbb5798 ("vringh: host-side implementation of virtio rings.") Signed-off-by: Xie Yongji Signed-off-by: Fam Zheng Message-Id: <20220505100910.137-1-xieyongji@bytedance.com> Signed-off-by: Michael S. Tsirkin Acked-by: Jason Wang Signed-off-by: Sasha Levin

vringh: Use wiov->used to check for read/write desc order

2021-08-11T10:44:24Z

As __vringh_iov() traverses a descriptor chain, it populates each descriptor entry into either read or write vring iov and increments that iov's ->used member. So, as we iterate over a descriptor chain, at any point, (riov/wriov)->used value gives the number of descriptor enteries available, which are to be read or written by the device. As all read iovs must precede the write iovs, wiov->used should be zero when we are traversing a read descriptor. Current code checks for wiov->i, to figure out whether any previous entry in the current descriptor chain was a write descriptor. However, iov->i is only incremented, when these vring iovs are consumed, at a later point, and remain 0 in __vringh_iov(). So, correct the check for read and write descriptor order, to use wiov->used. Acked-by: Jason Wang Reviewed-by: Stefano Garzarella Signed-off-by: Neeraj Upadhyay Link: https://lore.kernel.org/r/1624591502-4827-1-git-send-email-neeraju@codeaurora.org Signed-off-by: Michael S. Tsirkin

vringh: implement vringh_kiov_advance()

2021-05-03T08:55:53Z

In some cases, it may be useful to provide a way to skip a number of bytes in a vringh_kiov. Let's implement vringh_kiov_advance() for this purpose, reusing the code from vringh_iov_xfer(). We replace that code calling the new vringh_kiov_advance(). Acked-by: Jason Wang Signed-off-by: Stefano Garzarella Link: https://lore.kernel.org/r/20210315163450.254396-6-sgarzare@redhat.com Signed-off-by: Michael S. Tsirkin

vringh: explain more about cleaning riov and wiov

2021-05-03T08:55:53Z

riov and wiov can be reused with subsequent calls of vringh_getdesc_*(). Let's add a paragraph in the documentation of these functions to better explain when riov and wiov need to be cleaned up. Acked-by: Jason Wang Signed-off-by: Stefano Garzarella Link: https://lore.kernel.org/r/20210315163450.254396-5-sgarzare@redhat.com Signed-off-by: Michael S. Tsirkin

vringh: reset kiov 'consumed' field in __vringh_iov()

2021-05-03T08:55:53Z

__vringh_iov() overwrites the contents of riov and wiov, in fact it resets the 'i' and 'used' fields, but also the 'consumed' field should be reset to avoid an inconsistent state. Acked-by: Jason Wang Signed-off-by: Stefano Garzarella Link: https://lore.kernel.org/r/20210315163450.254396-4-sgarzare@redhat.com Signed-off-by: Michael S. Tsirkin

vringh: add 'iotlb_lock' to synchronize iotlb accesses

2021-05-03T08:55:52Z

Usually iotlb accesses are synchronized with a spinlock. Let's request it as a new parameter in vringh_set_iotlb() and hold it when we navigate the iotlb in iotlb_translate() to avoid race conditions with any new additions/deletions of ranges from the ioltb. Acked-by: Jason Wang Signed-off-by: Stefano Garzarella Link: https://lore.kernel.org/r/20210315163450.254396-3-sgarzare@redhat.com Signed-off-by: Michael S. Tsirkin

vhost: vringh: use krealloc_array()

2020-12-15T20:13:37Z

Use the helper that checks for overflows internally instead of manually calculating the size of the new array. Link: https://lkml.kernel.org/r/20201109110654.12547-5-brgl@bgdev.pl Signed-off-by: Bartosz Golaszewski Acked-by: Michael S. Tsirkin Cc: Alexander Shishkin Cc: Andy Shevchenko Cc: Borislav Petkov Cc: Borislav Petkov Cc: Christian Knig Cc: Christoph Lameter Cc: Daniel Vetter Cc: Daniel Vetter Cc: David Airlie Cc: David Rientjes Cc: Gustavo Padovan Cc: James Morse Cc: Jaroslav Kysela Cc: Jason Wang Cc: Joonsoo Kim Cc: Linus Walleij Cc: Maarten Lankhorst Cc: Mauro Carvalho Chehab Cc: Maxime Ripard Cc: Pekka Enberg Cc: Robert Richter Cc: Sumit Semwal Cc: Takashi Iwai Cc: Takashi Iwai Cc: Thomas Zimmermann Cc: Tony Luck Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

vringh: fix vringh_iov_push_*() documentation

2020-11-25T09:22:48Z

vringh_iov_push_*() functions don't have 'dst' parameter, but have the 'src' parameter. Replace 'dst' description with 'src' description. Signed-off-by: Stefano Garzarella Link: https://lore.kernel.org/r/20201116161653.102904-1-sgarzare@redhat.com Signed-off-by: Michael S. Tsirkin

vringh: fix __vringh_iov() when riov and wiov are different

2020-10-21T14:38:45Z

If riov and wiov are both defined and they point to different objects, only riov is initialized. If the wiov is not initialized by the caller, the function fails returning -EINVAL and printing "Readable desc 0x... after writable" error message. This issue happens when descriptors have both readable and writable buffers (eg. virtio-blk devices has virtio_blk_outhdr in the readable buffer and status as last byte of writable buffer) and we call __vringh_iov() to get both type of buffers in two different iovecs. Let's replace the 'else if' clause with 'if' to initialize both riov and wiov if they are not NULL. As checkpatch pointed out, we also avoid crashing the kernel when riov and wiov are both NULL, replacing BUG() with WARN_ON() and returning -EINVAL. Fixes: f87d0fbb5798 ("vringh: host-side implementation of virtio rings.") Cc: stable@vger.kernel.org Signed-off-by: Stefano Garzarella Link: https://lore.kernel.org/r/20201008204256.162292-1-sgarzare@redhat.com Signed-off-by: Michael S. Tsirkin

virtio: force spec specified alignment on types

2020-06-02T06:45:13Z

The ring element addresses are passed between components with different alignments assumptions. Thus, if guest/userspace selects a pointer and host then gets and dereferences it, we might need to decrease the compiler-selected alignment to prevent compiler on the host from assuming pointer is aligned. This actually triggers on ARM with -mabi=apcs-gnu - which is a deprecated configuration, but it seems safer to handle this generally. Note that userspace that allocates the memory is actually OK and does not need to be fixed, but userspace that gets it from guest or another process does need to be fixed. The later doesn't generally talk to the kernel so while it might be buggy it's not talking to the kernel in the buggy way - it's just using the header in the buggy way - so fixing header and asking userspace to recompile is the best we can do. I verified that the produced kernel binary on x86 is exactly identical before and after the change. Signed-off-by: Michael S. Tsirkin Acked-by: Jason Wang