From: "Michael S. Tsirkin" <mst@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: kevin.tian@intel.com, Lorenzo.Pieralisi@arm.com,
tnowicki@caviumnetworks.com,
Jean-Philippe Brucker <jean-philippe.brucker@arm.com>,
Jason Wang <jasowang@redhat.com>,
Alexey Kardashevskiy <aik@linux.ibm.com>,
Ram Pai <linuxram@us.ibm.com>,
linux-kernel@vger.kernel.org, Will.Deacon@arm.com,
virtualization@lists.linux-foundation.org, eric.auger@redhat.com,
iommu@lists.linux-foundation.org, Marc.Zyngier@arm.com,
Robin.Murphy@arm.com, bharat.bhushan@nxp.com,
linuxppc-dev@lists.ozlabs.org, joro@8bytes.org,
Thiago Jung Bauermann <bauerman@linux.ibm.com>,
David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [RFC PATCH] virtio_ring: Use DMA API if guest memory is encrypted
Date: Tue, 26 Mar 2019 12:53:59 -0400 [thread overview]
Message-ID: <20190325084348-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20190130074427.GA29516@lst.de>
On Wed, Jan 30, 2019 at 08:44:27AM +0100, Christoph Hellwig wrote:
> On Tue, Jan 29, 2019 at 09:36:08PM -0500, Michael S. Tsirkin wrote:
> > This has been discussed ad nauseum. virtio is all about compatibility.
> > Losing a couple of lines of code isn't worth breaking working setups.
> > People that want "just use DMA API no tricks" now have the option.
> > Setting a flag in a feature bit map is literally a single line
> > of code in the hypervisor. So stop pushing for breaking working
> > legacy setups and just fix it in the right place.
>
> I agree with the legacy aspect. What I am missing is an extremely
> strong wording that says you SHOULD always set this flag for new
> hosts, including an explanation why.
So as far as power is concerned, IIUC the issue they are struggling with is
that some platforms do not support pass-through mode in the emulated IOMMU.
Disabling PLATFORM_ACCESS is so far a way around that, unfortunately just for
virtio devices. I would like virtio-iommu to be able to address that need as
well.
--
MST
next prev parent reply other threads:[~2019-03-26 16:55 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <87zhrj8kcp.fsf@morokweng.localdomain>
2019-01-29 17:42 ` [RFC PATCH] virtio_ring: Use DMA API if guest memory is encrypted Thiago Jung Bauermann
2019-01-29 19:02 ` Michael S. Tsirkin
2019-01-30 2:24 ` Jason Wang
2019-01-30 2:36 ` Michael S. Tsirkin
2019-01-30 3:05 ` Jason Wang
2019-01-30 3:26 ` Michael S. Tsirkin
2019-01-30 7:44 ` Christoph Hellwig
2019-02-04 18:15 ` Thiago Jung Bauermann
2019-02-04 21:38 ` Michael S. Tsirkin
2019-02-05 7:24 ` Christoph Hellwig
2019-02-05 16:13 ` Michael S. Tsirkin
2019-03-26 16:53 ` Michael S. Tsirkin [this message]
2019-02-04 18:14 ` Thiago Jung Bauermann
2019-02-04 20:23 ` Michael S. Tsirkin
2019-03-20 16:13 ` Thiago Jung Bauermann
2019-03-20 21:17 ` Michael S. Tsirkin
2019-03-22 0:05 ` Thiago Jung Bauermann
2019-03-23 21:01 ` Michael S. Tsirkin
2019-03-25 0:57 ` David Gibson
2019-04-17 21:42 ` Thiago Jung Bauermann
2019-04-17 21:42 ` Thiago Jung Bauermann
2019-04-19 23:09 ` Michael S. Tsirkin
2019-04-25 1:01 ` Thiago Jung Bauermann
2019-04-25 1:18 ` Michael S. Tsirkin
2019-04-26 23:56 ` Thiago Jung Bauermann
2019-05-20 13:08 ` Michael S. Tsirkin
2019-05-20 13:16 ` Michael S. Tsirkin
2019-06-04 1:13 ` Thiago Jung Bauermann
2019-06-04 1:42 ` Michael S. Tsirkin
2019-06-28 1:58 ` Thiago Jung Bauermann
2019-07-01 14:17 ` Michael S. Tsirkin
2019-07-14 5:51 ` Thiago Jung Bauermann
2019-07-15 14:35 ` Michael S. Tsirkin
2019-07-15 20:29 ` Thiago Jung Bauermann
2019-07-15 20:36 ` Michael S. Tsirkin
2019-07-15 22:03 ` Thiago Jung Bauermann
2019-07-15 22:16 ` Michael S. Tsirkin
2019-07-15 23:05 ` Thiago Jung Bauermann
2019-07-15 23:24 ` Benjamin Herrenschmidt
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