litmus-rt-ext-res.git/drivers/virtio, branch EXT-RES

virtio_balloon: init 1st buffer in stats vq

2017-03-31T08:31:45+00:00

commit fc8653228c8588a120f6b5dad6983b7b61ff669e upstream.

When init_vqs runs, virtio_balloon.stats is either uninitialized or
contains stale values. The host updates its state with garbage data
because it has no way of knowing that this is just a marker buffer
used for signaling.

This patch updates the stats before pushing the initial buffer.

Alternative fixes:
* Push an empty buffer in init_vqs. Not easily done with the current
  virtio implementation and violates the spec "Driver MUST supply the
  same subset of statistics in all buffers submitted to the statsq".
* Push a buffer with invalid tags in init_vqs. Violates the same
  spec clause, plus "invalid tag" is not really defined.

Note: the spec says:
	When using the legacy interface, the device SHOULD ignore all values in
	the first buffer in the statsq supplied by the driver after device
	initialization. Note: Historically, drivers supplied an uninitialized
	buffer in the first buffer.

Unfortunately QEMU does not seem to implement the recommendation
even for the legacy interface.

Signed-off-by: Ladi Prosek 
Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Greg Kroah-Hartman

mm balloon: umount balloon_mnt when removing vb device

2017-03-12T05:41:43+00:00

commit 9c57b5808c625f4fc93da330b932647eaff321f7 upstream.

With CONFIG_BALLOON_COMPACTION=y the kernel will mount balloon_mnt for
balloon page migration when we probe a virtio_balloon device.  However
we do not unmount it when removing the device.  Fix this.

Fixes: b1123ea6d3b3 ("mm: balloon: use general non-lru movable page feature")
Link: http://lkml.kernel.org/r/1486531318-35189-1-git-send-email-xieyisheng1@huawei.com
Signed-off-by: Yisheng Xie 
Acked-by: Minchan Kim 
Cc: Rafael Aquini 
Cc: Konstantin Khlebnikov 
Cc: Gioh Kim 
Cc: Vlastimil Babka 
Cc: Michal Hocko 
Cc: Michael S. Tsirkin 
Cc: Jason Wang 
Cc: Hanjun Guo 
Cc: Xishi Qiu 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

Revert "vring: Force use of DMA API for ARM-based systems with legacy devices"

2017-02-09T07:08:28+00:00

commit 0d5415b489f68b58e1983a53793d25d53098ed4b upstream.

This reverts commit c7070619f3408d9a0dffbed9149e6f00479cf43b.

This has been shown to regress on some ARM systems:

by forcing on DMA API usage for ARM systems, we have inadvertently
kicked open a hornets' nest in terms of cache-coherency. Namely that
unless the virtio device is explicitly described as capable of coherent
DMA by firmware, the DMA APIs on ARM and other DT-based platforms will
assume it is non-coherent. This turns out to cause a big problem for the
likes of QEMU and kvmtool, which generate virtio-mmio devices in their
guest DTs but neglect to add the often-overlooked "dma-coherent"
property; as a result, we end up with the guest making non-cacheable
accesses to the vring, the host doing so cacheably, both talking past
each other and things going horribly wrong.

We are working on a safer work-around.

Fixes: c7070619f340 ("vring: Force use of DMA API for ARM-based systems with legacy devices")
Reported-by: Robin Murphy 
Signed-off-by: Will Deacon 
Signed-off-by: Michael S. Tsirkin 
Acked-by: Marc Zyngier 
Signed-off-by: Greg Kroah-Hartman

virtio_mmio: Set DMA masks appropriately

2017-02-01T07:33:13+00:00

commit f7f6634d23830ff74335734fbdb28ea109c1f349 upstream.

Once DMA API usage is enabled, it becomes apparent that virtio-mmio is
inadvertently relying on the default 32-bit DMA mask, which leads to
problems like rapidly exhausting SWIOTLB bounce buffers.

Ensure that we set the appropriate 64-bit DMA mask whenever possible,
with the coherent mask suitably limited for the legacy vring as per
a0be1db4304f ("virtio_pci: Limit DMA mask to 44 bits for legacy virtio
devices").

Cc: Andy Lutomirski 
Cc: Michael S. Tsirkin 
Reported-by: Jean-Philippe Brucker 
Fixes: b42111382f0e ("virtio_mmio: Use the DMA API if enabled")
Signed-off-by: Robin Murphy 
Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Greg Kroah-Hartman

vring: Force use of DMA API for ARM-based systems with legacy devices

2017-02-01T07:33:05+00:00

commit c7070619f3408d9a0dffbed9149e6f00479cf43b upstream.

Booting Linux on an ARM fastmodel containing an SMMU emulation results
in an unexpected I/O page fault from the legacy virtio-blk PCI device:

[    1.211721] arm-smmu-v3 2b400000.smmu: event 0x10 received:
[    1.211800] arm-smmu-v3 2b400000.smmu:	0x00000000fffff010
[    1.211880] arm-smmu-v3 2b400000.smmu:	0x0000020800000000
[    1.211959] arm-smmu-v3 2b400000.smmu:	0x00000008fa081002
[    1.212075] arm-smmu-v3 2b400000.smmu:	0x0000000000000000
[    1.212155] arm-smmu-v3 2b400000.smmu: event 0x10 received:
[    1.212234] arm-smmu-v3 2b400000.smmu:	0x00000000fffff010
[    1.212314] arm-smmu-v3 2b400000.smmu:	0x0000020800000000
[    1.212394] arm-smmu-v3 2b400000.smmu:	0x00000008fa081000
[    1.212471] arm-smmu-v3 2b400000.smmu:	0x0000000000000000



This is because the legacy virtio-blk device is behind an SMMU, so we
have consequently swizzled its DMA ops and configured the SMMU to
translate accesses. This then requires the vring code to use the DMA API
to establish translations, otherwise all transactions will result in
fatal faults and termination.

Given that ARM-based systems only see an SMMU if one is really present
(the topology is all described by firmware tables such as device-tree or
IORT), then we can safely use the DMA API for all legacy virtio devices.
Modern devices can advertise the prescense of an IOMMU using the
VIRTIO_F_IOMMU_PLATFORM feature flag.

Cc: Andy Lutomirski 
Cc: Michael S. Tsirkin 
Fixes: 876945dbf649 ("arm64: Hook up IOMMU dma_ops")
Signed-off-by: Will Deacon 
Signed-off-by: Michael S. Tsirkin 
Acked-by: Marc Zyngier 
Signed-off-by: Greg Kroah-Hartman

virtio_ring: mark vring_dma_dev inline

2016-10-30T22:40:08+00:00

This inline function is unused on configurations
where dma_map/unmap are empty macros.

Make the function inline to avoid gcc errors because
of an unused static function.

Signed-off-by: Michael S. Tsirkin

virtio: remove config.c

2016-10-30T22:21:45+00:00

Remove unused file config.c

Signed-off-by: Juergen Gross 
Signed-off-by: Michael S. Tsirkin

virtio: update balloon size in balloon "probe"

2016-10-30T22:21:41+00:00

The following commit 'fad7b7b27b6a (virtio_balloon: Use a workqueue
instead of "vballoon" kthread)' has added a regression. Original code with
kthread starts the thread inside probe and checks the necessity to update
balloon inside the thread immediately.

Nowadays the code behaves differently. Work is queued only on the first
command from the host after the negotiation. Thus there is a window
especially at the guest startup or the module reloading when the balloon
size is not updated until the notification from the host.

This patch adds balloon size check at the end of the probe to match
original behaviour.

Signed-off-by: Konstantin Neumoin 
Signed-off-by: Denis V. Lunev 
Signed-off-by: Michael S. Tsirkin

virtio_ring: Make interrupt suppression spec compliant

2016-10-30T22:21:40+00:00

According to the spec, if the VIRTIO_RING_F_EVENT_IDX feature bit is
negotiated the driver MUST set flags to 0. Not dirtying the available
ring in virtqueue_disable_cb also has a minor positive performance
impact, improving L1 dcache load missed by ~0.5% in vring_bench.

Writes to the used event field (vring_used_event) are still unconditional.

Cc: Michael S. Tsirkin 
Cc:  # f277ec4 virtio_ring: shadow available
Cc: 
Signed-off-by: Ladi Prosek 
Signed-off-by: Michael S. Tsirkin

virtio_pci: Limit DMA mask to 44 bits for legacy virtio devices

2016-10-30T22:21:39+00:00

Legacy virtio defines the virtqueue base using a 32-bit PFN field, with
a read-only register indicating a fixed page size of 4k.

This can cause problems for DMA allocators that allocate top down from
the DMA mask, which is set to 64 bits. In this case, the addresses are
silently truncated to 44-bit, leading to IOMMU faults, failure to read
from the queue or data corruption.

This patch restricts the coherent DMA mask for legacy PCI virtio devices
to 44 bits, which matches the specification.

Cc: stable@vger.kernel.org
Cc: Andy Lutomirski 
Cc: Michael S. Tsirkin 
Cc: Benjamin Serebrin 
Signed-off-by: Will Deacon 
Signed-off-by: Michael S. Tsirkin