From: Christoph Hellwig <hch@infradead.org>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
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: Sun, 5 Aug 2018 00:25:06 -0700 [thread overview]
Message-ID: <20180805072506.GA23288@infradead.org> (raw)
In-Reply-To: <20180805030326-mutt-send-email-mst@kernel.org>
On Sun, Aug 05, 2018 at 03:09:55AM +0300, Michael S. Tsirkin wrote:
> So in this case however I'm not sure what exactly do we want to add. It
> seems that from point of view of the device, there is nothing special -
> it just gets a PA and writes there. It also seems that guest does not
> need to get any info from the device either. Instead guest itself needs
> device to DMA into specific addresses, for its own reasons.
>
> It seems that the fact that within guest it's implemented using a bounce
> buffer and that it's easiest to do by switching virtio to use the DMA API
> isn't something virtio spec concerns itself with.
And that is exactly what we added bus_dma_mask for - the case where
the device itself has not limitation (or a bigger limitation), but
the platform limits the accessible dma ranges. One typical case is
a PCIe root port that is only connected to the CPU through an
interconnect that is limited to 32 address bits for example.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: robh@kernel.org, srikar@linux.vnet.ibm.com,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
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, mpe@ellerman.id.au,
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: Sun, 5 Aug 2018 00:25:06 -0700 [thread overview]
Message-ID: <20180805072506.GA23288@infradead.org> (raw)
In-Reply-To: <20180805030326-mutt-send-email-mst@kernel.org>
On Sun, Aug 05, 2018 at 03:09:55AM +0300, Michael S. Tsirkin wrote:
> So in this case however I'm not sure what exactly do we want to add. It
> seems that from point of view of the device, there is nothing special -
> it just gets a PA and writes there. It also seems that guest does not
> need to get any info from the device either. Instead guest itself needs
> device to DMA into specific addresses, for its own reasons.
>
> It seems that the fact that within guest it's implemented using a bounce
> buffer and that it's easiest to do by switching virtio to use the DMA API
> isn't something virtio spec concerns itself with.
And that is exactly what we added bus_dma_mask for - the case where
the device itself has not limitation (or a bigger limitation), but
the platform limits the accessible dma ranges. One typical case is
a PCIe root port that is only connected to the CPU through an
interconnect that is limited to 32 address bits for example.
next prev parent reply other threads:[~2018-08-05 7:26 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
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 [this message]
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
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