linux.git/drivers/vhost/vhost.c, branch v4.4

vhost: replace % with & on data path

2015-12-07T15:28:10+00:00

We know vring num is a power of 2, so use &
to mask the high bits.

Signed-off-by: Michael S. Tsirkin

vhost: relax log address alignment

2015-12-07T15:27:54+00:00

commit 5d9a07b0de512b77bf28d2401e5fe3351f00a240 ("vhost: relax used
address alignment") fixed the alignment for the used virtual address,
but not for the physical address used for logging.

That's a mistake: alignment should clearly be the same for virtual and
physical addresses,

Cc: stable@vger.kernel.org
Signed-off-by: Michael S. Tsirkin

vhost: fix error handling for memory region alloc

2015-07-27T15:05:05+00:00

callers of vhost_kvzalloc() expect the same behaviour on
allocation error as from kmalloc/vmalloc i.e. NULL return
value. So just return vzmalloc() returned value instead of
returning ERR_PTR(-ENOMEM)

Fixes: 4de7255f7d2be5 ("vhost: extend memory regions allocation to vmalloc")

Spotted-by: Dan Carpenter 
Suggested-by: Julia Lawall 
Signed-off-by: Igor Mammedov 
Signed-off-by: Michael S. Tsirkin

vhost: actually track log eventfd file

2015-07-27T15:04:58+00:00

While reviewing vhost log code, I found out that log_file is never
set. Note: I haven't tested the change (QEMU doesn't use LOG_FD yet).

Cc: stable@vger.kernel.org
Signed-off-by: Marc-André Lureau 
Signed-off-by: Michael S. Tsirkin

vhost: add max_mem_regions module parameter

2015-07-13T20:17:19+00:00

it became possible to use a bigger amount of memory
slots, which is used by memory hotplug for
registering hotplugged memory.
However QEMU crashes if it's used with more than ~60
pc-dimm devices and vhost-net enabled since host kernel
in module vhost-net refuses to accept more than 64
memory regions.

Allow to tweak limit via max_mem_regions module paramemter
with default value set to 64 slots.

Signed-off-by: Igor Mammedov 
Signed-off-by: Michael S. Tsirkin

vhost: extend memory regions allocation to vmalloc

2015-07-13T20:17:18+00:00

with large number of memory regions we could end up with
high order allocations and kmalloc could fail if
host is under memory pressure.
Considering that memory regions array is used on hot path
try harder to allocate using kmalloc and if it fails resort
to vmalloc.
It's still better than just failing vhost_set_memory() and
causing guest crash due to it when a new memory hotplugged
to guest.

I'll still look at QEMU side solution to reduce amount of
memory regions it feeds to vhost to make things even better,
but it doesn't hurt for kernel to behave smarter and don't
crash older QEMU's which could use large amount of memory
regions.

Signed-off-by: Igor Mammedov 
Signed-off-by: Michael S. Tsirkin

vhost: use binary search instead of linear in find_region()

2015-07-01T08:12:12+00:00

For default region layouts performance stays the same
as linear search i.e. it takes around 210ns average for
translate_desc() that inlines find_region().

But it scales better with larger amount of regions,
235ns BS vs 300ns LS with 55 memory regions
and it will be about the same values when allowed number
of slots is increased to 509 like it has been done in kvm.

Signed-off-by: Igor Mammedov 

Signed-off-by: Michael S. Tsirkin

vhost: cross-endian support for legacy devices

2015-06-01T13:48:55+00:00

This patch brings cross-endian support to vhost when used to implement
legacy virtio devices. Since it is a relatively rare situation, the
feature availability is controlled by a kernel config option (not set
by default).

The vq->is_le boolean field is added to cache the endianness to be
used for ring accesses. It defaults to native endian, as expected
by legacy virtio devices. When the ring gets active, we force little
endian if the device is modern. When the ring is deactivated, we
revert to the native endian default.

If cross-endian was compiled in, a vq->user_be boolean field is added
so that userspace may request a specific endianness. This field is
used to override the default when activating the ring of a legacy
device. It has no effect on modern devices.

Signed-off-by: Greg Kurz 

Signed-off-by: Michael S. Tsirkin 
Reviewed-by: Cornelia Huck 
Reviewed-by: David Gibson

vhost: switch vhost get_indirect() to iov_iter, kill memcpy_fromiovec()

2015-02-04T06:34:15+00:00

Cc: Michael S. Tsirkin 
Cc: kvm@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: Al Viro

vhost: relax used address alignment

2014-12-29T08:55:06+00:00

virtio 1.0 only requires used address to be 4 byte aligned,
vhost required 8 bytes (size of vring_used_elem).
Fix up vhost to match that.

Additionally, while vhost correctly requires 8 byte
alignment for log, it's unconnected to used ring:
it's a consequence that log has u64 entries.
Tweak code to make that clearer.

Signed-off-by: Michael S. Tsirkin