linux-kernel - Re: [PATCH 0/3] Fix virtio-blk issue with SWIOTLB

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 11 Jan 2019 11:29:31 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Joerg Roedel <joro@...tes.org>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:     Jens Axboe <axboe@...nel.dk>,
        virtualization@...ts.linux-foundation.org,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        iommu@...ts.linux-foundation.org, jfehlig@...e.com,
        jon.grimm@....com, brijesh.singh@....com, hch@....de
Subject: Re: [PATCH 0/3] Fix virtio-blk issue with SWIOTLB


On 2019/1/10 下午9:44, Joerg Roedel wrote:
> 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.


Just wonder if my understanding is correct IOMMU_PLATFORM must be set 
for all virtio devices under AMD-SEV guests?

Thanks


>
> 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(-)
>