From: David Gibson <david@gibson.dropbear.id.au>
To: Ram Pai <linuxram@us.ibm.com>
Cc: andmike@us.ibm.com, sukadev@linux.vnet.ibm.com,
mdroth@linux.vnet.ibm.com, b.zolnierkie@samsung.com,
mpe@ellerman.id.au, jasowang@redhat.com, aik@linux.ibm.com,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org, paulus@ozlabs.org,
iommu@lists.linux-foundation.org, paul.burton@mips.com,
benh@kernel.crashing.org, linuxppc-dev@lists.ozlabs.org,
hch@lst.de, robin.murphy@arm.com
Subject: Re: [PATCH 2/2] virtio_ring: Use DMA API if memory is encrypted
Date: Mon, 14 Oct 2019 15:52:35 +1100 [thread overview]
Message-ID: <20191014045235.GO4080@umbus.fritz.box> (raw)
In-Reply-To: <1570843519-8696-3-git-send-email-linuxram@us.ibm.com>
[-- Attachment #1.1: Type: text/plain, Size: 1752 bytes --]
On Fri, Oct 11, 2019 at 06:25:19PM -0700, Ram Pai wrote:
> From: Thiago Jung Bauermann <bauerman@linux.ibm.com>
>
> Normally, virtio enables DMA API with VIRTIO_F_IOMMU_PLATFORM, which must
> be set by both device and guest driver. However, as a hack, when DMA API
> returns physical addresses, guest driver can use the DMA API; even though
> device does not set VIRTIO_F_IOMMU_PLATFORM and just uses physical
> addresses.
>
> Doing this works-around POWER secure guests for which only the bounce
> buffer is accessible to the device, but which don't set
> VIRTIO_F_IOMMU_PLATFORM due to a set of hypervisor and architectural bugs.
> To guard against platform changes, breaking any of these assumptions down
> the road, we check at probe time and fail if that's not the case.
>
> cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> cc: David Gibson <david@gibson.dropbear.id.au>
> cc: Michael Ellerman <mpe@ellerman.id.au>
> cc: Paul Mackerras <paulus@ozlabs.org>
> cc: Michael Roth <mdroth@linux.vnet.ibm.com>
> cc: Alexey Kardashevskiy <aik@linux.ibm.com>
> cc: Jason Wang <jasowang@redhat.com>
> cc: Christoph Hellwig <hch@lst.de>
> Suggested-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Ram Pai <linuxram@us.ibm.com>
> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
I don't know that this is the most elegant solution possible. But
it's simple, gets the job done and pretty unlikely to cause mysterious
breakage down the road.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
[-- Attachment #2: Type: text/plain, Size: 156 bytes --]
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2019-10-14 5:08 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-12 1:25 [PATCH 0/2] virtio: Support encrypted memory on powerpc secure guests Ram Pai
2019-10-12 1:25 ` [PATCH 1/2] dma-mapping: Add dma_addr_is_phys_addr() Ram Pai
2019-10-12 1:25 ` [PATCH 2/2] virtio_ring: Use DMA API if memory is encrypted Ram Pai
2019-10-14 4:52 ` David Gibson [this message]
2019-10-15 7:35 ` Christoph Hellwig
2019-10-16 7:55 ` Ram Pai
2019-10-17 2:33 ` Jason Wang
2019-10-21 8:36 ` David Gibson
2019-10-14 4:51 ` [PATCH 1/2] dma-mapping: Add dma_addr_is_phys_addr() David Gibson
2019-10-14 10:29 ` Robin Murphy
2019-10-15 7:30 ` Ram Pai
2019-10-15 7:31 ` Christoph Hellwig
2019-10-12 1:36 ` [PATCH 0/2] virtio: Support encrypted memory on powerpc secure guests Ram Pai
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191014045235.GO4080@umbus.fritz.box \
--to=david@gibson.dropbear.id.au \
--cc=aik@linux.ibm.com \
--cc=andmike@us.ibm.com \
--cc=b.zolnierkie@samsung.com \
--cc=benh@kernel.crashing.org \
--cc=hch@lst.de \
--cc=iommu@lists.linux-foundation.org \
--cc=jasowang@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=linuxram@us.ibm.com \
--cc=mdroth@linux.vnet.ibm.com \
--cc=mpe@ellerman.id.au \
--cc=paul.burton@mips.com \
--cc=paulus@ozlabs.org \
--cc=robin.murphy@arm.com \
--cc=sukadev@linux.vnet.ibm.com \
--cc=virtualization@lists.linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).