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From: Joerg Roedel <joro@8bytes.org>
To: "Michael S . Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>,
	virtualization@lists.linux-foundation.org,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	iommu@lists.linux-foundation.org, jfehlig@suse.com,
	jon.grimm@amd.com, brijesh.singh@amd.com, hch@lst.de,
	Joerg Roedel <joro@8bytes.org>
Subject: [PATCH 0/3] Fix virtio-blk issue with SWIOTLB
Date: Thu, 10 Jan 2019 14:44:30 +0100
Message-ID: <20190110134433.15672-1-joro@8bytes.org> (raw)

Hi,

there is a problem with virtio-blk driven devices when
virtio-ring uses SWIOTLB through the DMA-API. This happens
for example in AMD-SEV enabled guests, where the guest RAM
is mostly encrypted and all emulated DMA has to happen
to/from the SWIOTLB aperture.

The problem is a limitation of the SWIOTLB implementation,
which does not support allocations larger than 256kb. When
the virtio-blk driver tries to read/write a block larger
than that, the allocation of the dma-handle fails and an IO
error is reported.

This patch-set adds a check to the virtio-code whether it
might be using SWIOTLB bounce buffering and limits the
maximum segment size in the virtio-blk driver in this case,
so that it doesn't try to do larger reads/writes.

Please review.

Thanks,

	Joerg

Joerg Roedel (3):
  swiotlb: Export maximum allocation size
  virtio: Introduce virtio_max_dma_size()
  virtio-blk: Consider virtio_max_dma_size() for maximum segment size

 drivers/block/virtio_blk.c   | 10 ++++++----
 drivers/virtio/virtio_ring.c | 11 +++++++++++
 include/linux/swiotlb.h      | 12 ++++++++++++
 include/linux/virtio.h       |  2 ++
 4 files changed, 31 insertions(+), 4 deletions(-)

-- 
2.17.1


             reply index

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-10 13:44 Joerg Roedel [this message]
2019-01-10 13:44 ` [PATCH 1/3] swiotlb: Export maximum allocation size Joerg Roedel
2019-01-10 17:02   ` Konrad Rzeszutek Wilk
2019-01-11  9:12     ` Joerg Roedel
2019-01-14 20:49       ` Konrad Rzeszutek Wilk
2019-01-14 21:59         ` Michael S. Tsirkin
2019-01-15 13:05           ` Christoph Hellwig
2019-01-10 13:44 ` [PATCH 2/3] virtio: Introduce virtio_max_dma_size() Joerg Roedel
2019-01-10 13:44 ` [PATCH 3/3] virtio-blk: Consider virtio_max_dma_size() for maximum segment size Joerg Roedel
2019-01-10 13:59 ` [PATCH 0/3] Fix virtio-blk issue with SWIOTLB Christoph Hellwig
2019-01-10 14:26   ` Joerg Roedel
2019-01-11  3:29 ` Jason Wang
2019-01-11  9:15   ` Joerg Roedel
2019-01-14  9:41     ` Jason Wang
2019-01-14  9:50       ` Christoph Hellwig
2019-01-14 12:41         ` Jason Wang
2019-01-14 18:20           ` Michael S. Tsirkin
2019-01-14 19:09             ` Singh, Brijesh
2019-01-14 19:12             ` Robin Murphy
2019-01-14 20:22               ` Christoph Hellwig
2019-01-14 20:29               ` Michael S. Tsirkin
2019-01-14 20:19             ` Christoph Hellwig
2019-01-14 20:48               ` Michael S. Tsirkin
2019-01-15 13:09                 ` Christoph Hellwig
2019-01-15  8:37             ` Joerg Roedel
2019-01-15 13:20               ` Christoph Hellwig
2019-01-16 14:16                 ` Michael S. Tsirkin

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