From: Christoph Hellwig <hch@infradead.org> To: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Christoph Hellwig <hch@infradead.org>, "Michael S. Tsirkin" <mst@redhat.com>, Will Deacon <will.deacon@arm.com>, Anshuman Khandual <khandual@linux.vnet.ibm.com>, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, aik@ozlabs.ru, robh@kernel.org, joe@perches.com, elfring@users.sourceforge.net, david@gibson.dropbear.id.au, jasowang@redhat.com, mpe@ellerman.id.au, linuxram@us.ibm.com, haren@linux.vnet.ibm.com, paulus@samba.org, srikar@linux.vnet.ibm.com, robin.murphy@arm.com, jean-philippe.brucker@arm.com, marc.zyngier@arm.com Subject: Re: [RFC 0/4] Virtio uses DMA API for all devices Date: Sat, 4 Aug 2018 01:21:20 -0700 [thread overview] Message-ID: <20180804082120.GB4421@infradead.org> (raw) In-Reply-To: <22310f58605169fe9de83abf78b59f593ff7fbb7.camel@kernel.crashing.org> On Fri, Aug 03, 2018 at 01:58:46PM -0500, Benjamin Herrenschmidt wrote: > You are saying something along the lines of "I don't like an > instruction in your ISA, let's not support your entire CPU architecture > in Linux". No. I'm saying if you can't describe your architecture in the virtio spec document it is bogus. > Our setup is not fucked. It makes a LOT of sense and it's a very > sensible design. It's hitting a problem due to a corner case oddity in > virtio bypassing the MMU, we've worked around such corner cases many > times in the past without any problem, I fail to see what the problem > is here. No matter if you like it or not (I don't!) virtio is defined to bypass dma translations, it is very clearly stated in the spec. It has some ill-defined bits to bypass it, so if you want the dma mapping API to be used you'll have to set that bit (in its original form, a refined form, or an entirely newly defined sane form) and make sure your hypersivors always sets it. It's not rocket science, just a little bit for work to make sure your setup is actually going to work reliably and portably. > We aren't going to cancel years of HW and SW development for our Maybe you should have actually read the specs you are claiming to implemented before spending all that effort.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org> To: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: robh@kernel.org, srikar@linux.vnet.ibm.com, "Michael S. Tsirkin" <mst@redhat.com>, mpe@ellerman.id.au, Will Deacon <will.deacon@arm.com>, linux-kernel@vger.kernel.org, linuxram@us.ibm.com, virtualization@lists.linux-foundation.org, Christoph Hellwig <hch@infradead.org>, paulus@samba.org, marc.zyngier@arm.com, joe@perches.com, robin.murphy@arm.com, david@gibson.dropbear.id.au, linuxppc-dev@lists.ozlabs.org, elfring@users.sourceforge.net, haren@linux.vnet.ibm.com, Anshuman Khandual <khandual@linux.vnet.ibm.com> Subject: Re: [RFC 0/4] Virtio uses DMA API for all devices Date: Sat, 4 Aug 2018 01:21:20 -0700 [thread overview] Message-ID: <20180804082120.GB4421@infradead.org> (raw) In-Reply-To: <22310f58605169fe9de83abf78b59f593ff7fbb7.camel@kernel.crashing.org> On Fri, Aug 03, 2018 at 01:58:46PM -0500, Benjamin Herrenschmidt wrote: > You are saying something along the lines of "I don't like an > instruction in your ISA, let's not support your entire CPU architecture > in Linux". No. I'm saying if you can't describe your architecture in the virtio spec document it is bogus. > Our setup is not fucked. It makes a LOT of sense and it's a very > sensible design. It's hitting a problem due to a corner case oddity in > virtio bypassing the MMU, we've worked around such corner cases many > times in the past without any problem, I fail to see what the problem > is here. No matter if you like it or not (I don't!) virtio is defined to bypass dma translations, it is very clearly stated in the spec. It has some ill-defined bits to bypass it, so if you want the dma mapping API to be used you'll have to set that bit (in its original form, a refined form, or an entirely newly defined sane form) and make sure your hypersivors always sets it. It's not rocket science, just a little bit for work to make sure your setup is actually going to work reliably and portably. > We aren't going to cancel years of HW and SW development for our Maybe you should have actually read the specs you are claiming to implemented before spending all that effort.
next prev parent reply other threads:[~2018-08-04 8:21 UTC|newest] Thread overview: 240+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-07-20 3:59 [RFC 0/4] Virtio uses DMA API for all devices Anshuman Khandual 2018-07-20 3:59 ` [RFC 1/4] virtio: Define virtio_direct_dma_ops structure Anshuman Khandual 2018-07-20 3:59 ` Anshuman Khandual 2018-07-30 9:24 ` Christoph Hellwig 2018-07-30 9:24 ` Christoph Hellwig 2018-07-31 4:01 ` Anshuman Khandual 2018-07-31 4:01 ` Anshuman Khandual 2018-07-20 3:59 ` [RFC 2/4] virtio: Override device's DMA OPS with virtio_direct_dma_ops selectively Anshuman Khandual 2018-07-20 3:59 ` Anshuman Khandual 2018-07-28 8:56 ` Anshuman Khandual 2018-07-28 8:56 ` Anshuman Khandual 2018-07-28 21:16 ` Michael S. Tsirkin 2018-07-30 4:15 ` Anshuman Khandual 2018-07-30 4:15 ` Anshuman Khandual 2018-07-30 9:30 ` Christoph Hellwig 2018-07-31 6:39 ` Anshuman Khandual 2018-07-31 6:39 ` Anshuman Khandual 2018-07-30 9:30 ` Christoph Hellwig 2018-07-28 21:16 ` Michael S. Tsirkin 2018-07-30 9:25 ` Christoph Hellwig 2018-07-31 7:00 ` Anshuman Khandual 2018-07-31 7:00 ` Anshuman Khandual 2018-07-30 9:25 ` Christoph Hellwig 2018-07-20 3:59 ` [RFC 3/4] virtio: Force virtio core to use DMA API callbacks for all virtio devices Anshuman Khandual 2018-07-20 3:59 ` Anshuman Khandual 2018-07-20 3:59 ` [RFC 4/4] virtio: Add platform specific DMA API translation for virito devices Anshuman Khandual 2018-07-20 13:15 ` Michael S. Tsirkin 2018-07-20 13:15 ` Michael S. Tsirkin 2018-07-23 2:16 ` Anshuman Khandual 2018-07-23 2:16 ` Anshuman Khandual 2018-07-25 4:30 ` Anshuman Khandual 2018-07-25 4:30 ` Anshuman Khandual 2018-07-25 13:31 ` Michael S. Tsirkin 2018-07-25 13:31 ` Michael S. Tsirkin 2018-07-20 3:59 ` Anshuman Khandual 2018-07-20 13:16 ` [RFC 0/4] Virtio uses DMA API for all devices Michael S. Tsirkin 2018-07-20 13:16 ` Michael S. Tsirkin 2018-07-23 6:28 ` Anshuman Khandual 2018-07-23 9:08 ` Michael S. Tsirkin 2018-07-23 9:08 ` Michael S. Tsirkin 2018-07-25 3:26 ` Anshuman Khandual 2018-07-27 11:31 ` Michael S. Tsirkin 2018-07-27 11:31 ` Michael S. Tsirkin 2018-07-28 8:37 ` Anshuman Khandual 2018-07-28 8:37 ` Anshuman Khandual 2018-07-25 3:26 ` Anshuman Khandual 2018-07-23 6:28 ` Anshuman Khandual 2018-07-27 9:58 ` Will Deacon 2018-07-27 9:58 ` Will Deacon 2018-07-27 9:58 ` Will Deacon 2018-07-27 10:58 ` Anshuman Khandual 2018-07-27 10:58 ` Anshuman Khandual 2018-07-30 9:34 ` Christoph Hellwig 2018-07-30 9:34 ` Christoph Hellwig 2018-07-30 10:28 ` Michael S. Tsirkin 2018-07-30 10:28 ` Michael S. Tsirkin 2018-07-30 11:18 ` Christoph Hellwig 2018-07-30 11:18 ` Christoph Hellwig 2018-07-30 13:26 ` Michael S. Tsirkin 2018-07-30 13:26 ` Michael S. Tsirkin 2018-07-31 17:30 ` Christoph Hellwig 2018-07-31 17:30 ` Christoph Hellwig 2018-07-31 20:36 ` Benjamin Herrenschmidt 2018-07-31 20:36 ` Benjamin Herrenschmidt 2018-08-01 8:16 ` Will Deacon 2018-08-01 8:16 ` Will Deacon 2018-08-01 8:36 ` Christoph Hellwig 2018-08-01 8:36 ` Christoph Hellwig 2018-08-01 8:36 ` Christoph Hellwig 2018-08-01 9:05 ` Will Deacon 2018-08-01 9:05 ` Will Deacon 2018-08-01 22:41 ` Michael S. Tsirkin 2018-08-01 22:41 ` Michael S. Tsirkin 2018-08-01 22:35 ` Michael S. Tsirkin 2018-08-01 22:35 ` Michael S. Tsirkin 2018-08-02 15:24 ` Benjamin Herrenschmidt 2018-08-02 15:24 ` Benjamin Herrenschmidt 2018-08-02 15:41 ` Michael S. Tsirkin 2018-08-02 15:41 ` Michael S. Tsirkin 2018-08-02 16:01 ` Benjamin Herrenschmidt 2018-08-02 16:01 ` Benjamin Herrenschmidt 2018-08-02 17:19 ` Michael S. Tsirkin 2018-08-02 17:19 ` Michael S. Tsirkin 2018-08-02 17:53 ` Benjamin Herrenschmidt 2018-08-02 17:53 ` Benjamin Herrenschmidt 2018-08-02 20:52 ` Michael S. Tsirkin 2018-08-02 20:52 ` Michael S. Tsirkin 2018-08-02 21:13 ` Benjamin Herrenschmidt 2018-08-02 21:13 ` Benjamin Herrenschmidt 2018-08-02 21:51 ` Michael S. Tsirkin 2018-08-02 21:51 ` Michael S. Tsirkin 2018-08-03 7:05 ` Christoph Hellwig 2018-08-03 7:05 ` Christoph Hellwig 2018-08-03 15:58 ` Benjamin Herrenschmidt 2018-08-03 15:58 ` Benjamin Herrenschmidt 2018-08-03 16:02 ` Christoph Hellwig 2018-08-03 16:02 ` Christoph Hellwig 2018-08-03 18:58 ` Benjamin Herrenschmidt 2018-08-03 18:58 ` Benjamin Herrenschmidt 2018-08-04 8:21 ` Christoph Hellwig [this message] 2018-08-04 8:21 ` Christoph Hellwig 2018-08-05 1:10 ` Benjamin Herrenschmidt 2018-08-05 1:10 ` Benjamin Herrenschmidt 2018-08-05 1:10 ` Benjamin Herrenschmidt 2018-08-05 7:29 ` Christoph Hellwig 2018-08-05 7:29 ` Christoph Hellwig 2018-08-05 21:16 ` Benjamin Herrenschmidt 2018-08-05 21:16 ` Benjamin Herrenschmidt 2018-08-05 21:30 ` Benjamin Herrenschmidt 2018-08-05 21:30 ` Benjamin Herrenschmidt 2018-08-06 9:42 ` Christoph Hellwig 2018-08-06 9:42 ` Christoph Hellwig 2018-08-06 19:52 ` Benjamin Herrenschmidt 2018-08-06 19:52 ` Benjamin Herrenschmidt 2018-08-07 6:21 ` Christoph Hellwig 2018-08-07 6:42 ` Benjamin Herrenschmidt 2018-08-07 6:42 ` Benjamin Herrenschmidt 2018-08-07 13:55 ` Christoph Hellwig 2018-08-07 20:32 ` Benjamin Herrenschmidt 2018-08-07 20:32 ` Benjamin Herrenschmidt 2018-08-08 6:31 ` Christoph Hellwig 2018-08-08 6:31 ` Christoph Hellwig 2018-08-08 10:07 ` Benjamin Herrenschmidt 2018-08-08 10:07 ` Benjamin Herrenschmidt 2018-08-08 12:30 ` Christoph Hellwig 2018-08-08 13:18 ` Benjamin Herrenschmidt 2018-08-08 13:18 ` Benjamin Herrenschmidt 2018-08-08 20:31 ` Michael S. Tsirkin 2018-08-08 22:13 ` Benjamin Herrenschmidt 2018-08-08 22:13 ` Benjamin Herrenschmidt 2018-08-09 2:00 ` Benjamin Herrenschmidt 2018-08-09 2:00 ` Benjamin Herrenschmidt 2018-08-09 5:40 ` Christoph Hellwig 2018-08-09 5:40 ` Christoph Hellwig 2018-09-07 0:09 ` Jiandi An 2018-09-10 6:19 ` Christoph Hellwig 2018-09-10 6:19 ` Christoph Hellwig 2018-09-10 8:53 ` Gerd Hoffmann 2018-09-10 8:53 ` Gerd Hoffmann 2018-08-08 20:31 ` Michael S. Tsirkin 2018-08-08 12:30 ` Christoph Hellwig 2018-08-07 13:55 ` Christoph Hellwig 2018-08-07 6:21 ` Christoph Hellwig 2018-08-03 19:07 ` Michael S. Tsirkin 2018-08-03 19:07 ` Michael S. Tsirkin 2018-08-04 1:11 ` Benjamin Herrenschmidt 2018-08-04 1:11 ` Benjamin Herrenschmidt 2018-08-04 1:16 ` Benjamin Herrenschmidt 2018-08-04 1:16 ` Benjamin Herrenschmidt 2018-08-05 0:22 ` Michael S. Tsirkin 2018-08-05 4:52 ` Benjamin Herrenschmidt 2018-08-05 4:52 ` Benjamin Herrenschmidt 2018-08-06 13:46 ` Michael S. Tsirkin 2018-08-06 19:56 ` Benjamin Herrenschmidt 2018-08-06 19:56 ` Benjamin Herrenschmidt 2018-08-06 20:35 ` Michael S. Tsirkin 2018-08-06 21:26 ` Benjamin Herrenschmidt 2018-08-06 21:26 ` Benjamin Herrenschmidt 2018-08-06 21:46 ` Michael S. Tsirkin 2018-08-06 21:46 ` Michael S. Tsirkin 2018-08-06 22:13 ` Benjamin Herrenschmidt 2018-08-06 22:13 ` Benjamin Herrenschmidt 2018-08-06 23:16 ` Benjamin Herrenschmidt 2018-08-06 23:16 ` Benjamin Herrenschmidt 2018-08-06 23:45 ` Michael S. Tsirkin 2018-08-07 0:18 ` Benjamin Herrenschmidt 2018-08-07 0:18 ` Benjamin Herrenschmidt 2018-08-07 6:32 ` Christoph Hellwig 2018-08-07 6:32 ` Christoph Hellwig 2018-08-06 23:45 ` Michael S. Tsirkin 2018-08-07 6:27 ` Christoph Hellwig 2018-08-07 6:27 ` Christoph Hellwig 2018-08-07 6:44 ` Benjamin Herrenschmidt 2018-08-07 6:44 ` Benjamin Herrenschmidt 2018-08-07 6:18 ` Christoph Hellwig 2018-08-07 6:18 ` Christoph Hellwig 2018-08-07 6:16 ` Christoph Hellwig 2018-08-07 6:16 ` Christoph Hellwig 2018-08-06 23:18 ` Benjamin Herrenschmidt 2018-08-06 23:18 ` Benjamin Herrenschmidt 2018-08-07 6:12 ` Christoph Hellwig 2018-08-07 6:12 ` Christoph Hellwig 2018-08-06 20:35 ` Michael S. Tsirkin 2018-08-06 13:46 ` Michael S. Tsirkin 2018-08-05 0:22 ` Michael S. Tsirkin 2018-08-04 1:18 ` Benjamin Herrenschmidt 2018-08-04 1:18 ` Benjamin Herrenschmidt 2018-08-04 1:22 ` Benjamin Herrenschmidt 2018-08-04 1:22 ` Benjamin Herrenschmidt 2018-08-05 0:23 ` Michael S. Tsirkin 2018-08-05 0:23 ` Michael S. Tsirkin 2018-08-03 19:17 ` Michael S. Tsirkin 2018-08-03 19:17 ` Michael S. Tsirkin 2018-08-04 8:15 ` Christoph Hellwig 2018-08-04 8:15 ` Christoph Hellwig 2018-08-05 0:09 ` Michael S. Tsirkin 2018-08-05 0:09 ` Michael S. Tsirkin 2018-08-05 1:11 ` Benjamin Herrenschmidt 2018-08-05 1:11 ` Benjamin Herrenschmidt 2018-08-05 7:25 ` Christoph Hellwig 2018-08-05 7:25 ` Christoph Hellwig 2018-08-05 0:53 ` Benjamin Herrenschmidt 2018-08-05 0:53 ` Benjamin Herrenschmidt 2018-08-05 0:27 ` Michael S. Tsirkin 2018-08-05 0:27 ` Michael S. Tsirkin 2018-08-06 14:05 ` Will Deacon 2018-08-06 14:05 ` Will Deacon 2018-08-01 21:56 ` Michael S. Tsirkin 2018-08-01 21:56 ` Michael S. Tsirkin 2018-08-02 15:33 ` Benjamin Herrenschmidt 2018-08-02 15:33 ` Benjamin Herrenschmidt 2018-08-02 20:53 ` Michael S. Tsirkin 2018-08-03 7:06 ` Christoph Hellwig 2018-08-03 7:06 ` Christoph Hellwig 2018-08-02 20:53 ` Michael S. Tsirkin 2018-08-02 20:55 ` Michael S. Tsirkin 2018-08-02 20:55 ` Michael S. Tsirkin 2018-08-03 2:41 ` Jason Wang 2018-08-03 2:41 ` Jason Wang 2018-08-03 19:08 ` Michael S. Tsirkin 2018-08-04 1:21 ` Benjamin Herrenschmidt 2018-08-04 1:21 ` Benjamin Herrenschmidt 2018-08-05 0:24 ` Michael S. Tsirkin 2018-08-05 0:24 ` Michael S. Tsirkin 2018-08-06 9:02 ` Anshuman Khandual 2018-08-06 9:02 ` Anshuman Khandual 2018-08-06 13:36 ` Michael S. Tsirkin 2018-08-06 13:36 ` Michael S. Tsirkin 2018-08-06 15:24 ` Christoph Hellwig 2018-08-06 16:06 ` Michael S. Tsirkin 2018-08-06 16:06 ` Michael S. Tsirkin 2018-08-06 16:10 ` Christoph Hellwig 2018-08-06 16:10 ` Christoph Hellwig 2018-08-06 16:13 ` Michael S. Tsirkin 2018-08-06 16:13 ` Michael S. Tsirkin 2018-08-06 16:34 ` Christoph Hellwig 2018-08-06 16:34 ` Christoph Hellwig 2018-08-06 15:24 ` Christoph Hellwig 2018-08-03 19:08 ` Michael S. Tsirkin 2018-07-20 3:59 Anshuman Khandual
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=20180804082120.GB4421@infradead.org \ --to=hch@infradead.org \ --cc=aik@ozlabs.ru \ --cc=benh@kernel.crashing.org \ --cc=david@gibson.dropbear.id.au \ --cc=elfring@users.sourceforge.net \ --cc=haren@linux.vnet.ibm.com \ --cc=jasowang@redhat.com \ --cc=jean-philippe.brucker@arm.com \ --cc=joe@perches.com \ --cc=khandual@linux.vnet.ibm.com \ --cc=linux-kernel@vger.kernel.org \ --cc=linuxppc-dev@lists.ozlabs.org \ --cc=linuxram@us.ibm.com \ --cc=marc.zyngier@arm.com \ --cc=mpe@ellerman.id.au \ --cc=mst@redhat.com \ --cc=paulus@samba.org \ --cc=robh@kernel.org \ --cc=robin.murphy@arm.com \ --cc=srikar@linux.vnet.ibm.com \ --cc=virtualization@lists.linux-foundation.org \ --cc=will.deacon@arm.com \ /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: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.