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Tsirkin" To: Peng Fan Cc: sstabellini@kernel.org, boris.ostrovsky@oracle.com, jgross@suse.com, konrad.wilk@oracle.com, jasowang@redhat.com, x86@kernel.org, xen-devel@lists.xenproject.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, virtualization@lists.linux-foundation.org, linux-imx@nxp.com Subject: Re: [PATCH] xen: introduce xen_vring_use_dma Message-ID: <20200624050355-mutt-send-email-mst@kernel.org> References: <20200624091732.23944-1-peng.fan@nxp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200624091732.23944-1-peng.fan@nxp.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 24, 2020 at 05:17:32PM +0800, Peng Fan wrote: > Export xen_swiotlb for all platforms using xen swiotlb > > Use xen_swiotlb to determine when vring should use dma APIs to map the > ring: when xen_swiotlb is enabled the dma API is required. When it is > disabled, it is not required. > > Signed-off-by: Peng Fan Isn't there some way to use VIRTIO_F_IOMMU_PLATFORM for this? Xen was there first, but everyone else is using that now. > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index a2de775801af..768afd79f67a 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -252,7 +252,7 @@ static bool vring_use_dma_api(struct virtio_device *vdev) > * the DMA API if we're a Xen guest, which at least allows > * all of the sensible Xen configurations to work correctly. > */ > - if (xen_domain()) > + if (xen_vring_use_dma()) > return true; > > return false; The comment above this should probably be fixed. -- MST