From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH] virtio: Try to untangle DMA coherency Date: Thu, 2 Feb 2017 16:40:49 +0000 Message-ID: <20170202164049.GI13839@arm.com> References: <8a6494f6409c20b4609cd6bdcdd751f68b5c0564.1485951731.git.robin.murphy@arm.com> <20170201195732-mutt-send-email-mst@kernel.org> <20170201182659.GM8177@arm.com> <20170201210648-mutt-send-email-mst@kernel.org> <20170202112614.GB30577@arm.com> <20170202182224-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20170202182224-mutt-send-email-mst@kernel.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: "Michael S. Tsirkin" Cc: mark.rutland@arm.com, devicetree@vger.kernel.org, pawel.moll@arm.com, virtualization@lists.linux-foundation.org, robh+dt@kernel.org, Robin Murphy , linux-arm-kernel@lists.infradead.org List-Id: virtualization@lists.linuxfoundation.org On Thu, Feb 02, 2017 at 06:30:28PM +0200, Michael S. Tsirkin wrote: > I am inclined to say, for 4.10 let's revert > c7070619f3408d9a0dffbed9149e6f00479cf43b since what it fixes is not a > regression in 4.10. No complaints there, as long as we can keep working to fix this for 4.11 and onwards. You'll also need to cc stable on the revert. > So I think we can defer the fix to 4.11. > I think we still want f7f6634d23830ff74335734fbdb28ea109c1f349 > for hosts with virtio 1 support. > > All this will hopefully push hosts to just implement virtio 1. > For mmio the changes are very small: several new registers, > that's all. You want this for proper 64 bit dma mask anyway. As I've said, virtio 1 will have exactly the same issue unless we start requiring firmware to advertise dma-coherent/_CCA for virtio-mmio devices correctly. Will From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Thu, 2 Feb 2017 16:40:49 +0000 Subject: [PATCH] virtio: Try to untangle DMA coherency In-Reply-To: <20170202182224-mutt-send-email-mst@kernel.org> References: <8a6494f6409c20b4609cd6bdcdd751f68b5c0564.1485951731.git.robin.murphy@arm.com> <20170201195732-mutt-send-email-mst@kernel.org> <20170201182659.GM8177@arm.com> <20170201210648-mutt-send-email-mst@kernel.org> <20170202112614.GB30577@arm.com> <20170202182224-mutt-send-email-mst@kernel.org> Message-ID: <20170202164049.GI13839@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Feb 02, 2017 at 06:30:28PM +0200, Michael S. Tsirkin wrote: > I am inclined to say, for 4.10 let's revert > c7070619f3408d9a0dffbed9149e6f00479cf43b since what it fixes is not a > regression in 4.10. No complaints there, as long as we can keep working to fix this for 4.11 and onwards. You'll also need to cc stable on the revert. > So I think we can defer the fix to 4.11. > I think we still want f7f6634d23830ff74335734fbdb28ea109c1f349 > for hosts with virtio 1 support. > > All this will hopefully push hosts to just implement virtio 1. > For mmio the changes are very small: several new registers, > that's all. You want this for proper 64 bit dma mask anyway. As I've said, virtio 1 will have exactly the same issue unless we start requiring firmware to advertise dma-coherent/_CCA for virtio-mmio devices correctly. Will