From: Jean-Philippe Brucker <jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org> To: "Michael S. Tsirkin" <mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Cc: mark.rutland-5wv7dgnIgG8@public.gmane.org, peter.maydell-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, kevin.tian-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, tnowicki-M3mlKVOIwJVv6pq1l3V1OdBPR1lH4CV8@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, marc.zyngier-5wv7dgnIgG8@public.gmane.org, linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, jasowang-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, robin.murphy-5wv7dgnIgG8@public.gmane.org, kvmarm-FPEHb7Xf0XXUo1n7N8X6UoWGPAHP3yOg@public.gmane.org Subject: Re: [PATCH v3 5/7] iommu: Add virtio-iommu driver Date: Fri, 12 Oct 2018 19:54:53 +0100 [thread overview] Message-ID: <ba8d7b94-a806-276b-e64c-9e6c5c9e107b@arm.com> (raw) In-Reply-To: <20181012120953-mutt-send-email-mst-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> On 12/10/2018 17:35, Michael S. Tsirkin wrote: >> + list_del(&req->list); >> + kfree(req); > > So with DEBUG set, this will actually free memory that device still > DMA's into. Hardly pretty. I think you want to mark device broken, > queue the request and then wait for device to be reset. Ok, let's remove DEBUG for the moment >> +static int viommu_probe(struct virtio_device *vdev) >> +{ >> + struct device *parent_dev = vdev->dev.parent; >> + struct viommu_dev *viommu = NULL; >> + struct device *dev = &vdev->dev; >> + u64 input_start = 0; >> + u64 input_end = -1UL; >> + int ret; >> + >> + if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) >> + return -ENODEV; > > I'm a bit confused about what will happen if this device > happens to be behind an iommu itself. > > If we can't handle that, should we clear PLATFORM_IOMMU > e.g. like the balloon does? I think the DMA API can handle this device doing DMA through another IOMMU. I haven't tested this case because it is very unusual (IOMMUs themselves generally access the physical address space) but I don't see anything preventing it. What we can't handle is a device performing DMA through two daisy-chained IOMMUs, but clearing PLATFORM_IOMMU on the first one wouldn't make things work in that case, we'd need some core changes. >> +struct virtio_iommu_config { >> + /* Supported page sizes */ >> + __u64 page_size_mask; >> + /* Supported IOVA range */ >> + struct virtio_iommu_range { > > I'd rather we moved the definition outside even though gcc allows it - > some old userspace compilers might not. > >> + __u64 start; >> + __u64 end; >> + } input_range; >> + /* Max domain ID size */ >> + __u8 domain_bits; > > Let's add explicit padding here as well? Ok Thanks, Jean
WARNING: multiple messages have this Message-ID (diff)
From: Jean-Philippe Brucker <jean-philippe.brucker@arm.com> To: "Michael S. Tsirkin" <mst@redhat.com> Cc: mark.rutland@arm.com, peter.maydell@linaro.org, kevin.tian@intel.com, tnowicki@caviumnetworks.com, devicetree@vger.kernel.org, jasowang@redhat.com, linux-pci@vger.kernel.org, will.deacon@arm.com, virtualization@lists.linux-foundation.org, iommu@lists.linux-foundation.org, robh+dt@kernel.org, marc.zyngier@arm.com, robin.murphy@arm.com, kvmarm@lists.cs.columbia.edu Subject: Re: [PATCH v3 5/7] iommu: Add virtio-iommu driver Date: Fri, 12 Oct 2018 19:54:53 +0100 [thread overview] Message-ID: <ba8d7b94-a806-276b-e64c-9e6c5c9e107b@arm.com> (raw) In-Reply-To: <20181012120953-mutt-send-email-mst@kernel.org> On 12/10/2018 17:35, Michael S. Tsirkin wrote: >> + list_del(&req->list); >> + kfree(req); > > So with DEBUG set, this will actually free memory that device still > DMA's into. Hardly pretty. I think you want to mark device broken, > queue the request and then wait for device to be reset. Ok, let's remove DEBUG for the moment >> +static int viommu_probe(struct virtio_device *vdev) >> +{ >> + struct device *parent_dev = vdev->dev.parent; >> + struct viommu_dev *viommu = NULL; >> + struct device *dev = &vdev->dev; >> + u64 input_start = 0; >> + u64 input_end = -1UL; >> + int ret; >> + >> + if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) >> + return -ENODEV; > > I'm a bit confused about what will happen if this device > happens to be behind an iommu itself. > > If we can't handle that, should we clear PLATFORM_IOMMU > e.g. like the balloon does? I think the DMA API can handle this device doing DMA through another IOMMU. I haven't tested this case because it is very unusual (IOMMUs themselves generally access the physical address space) but I don't see anything preventing it. What we can't handle is a device performing DMA through two daisy-chained IOMMUs, but clearing PLATFORM_IOMMU on the first one wouldn't make things work in that case, we'd need some core changes. >> +struct virtio_iommu_config { >> + /* Supported page sizes */ >> + __u64 page_size_mask; >> + /* Supported IOVA range */ >> + struct virtio_iommu_range { > > I'd rather we moved the definition outside even though gcc allows it - > some old userspace compilers might not. > >> + __u64 start; >> + __u64 end; >> + } input_range; >> + /* Max domain ID size */ >> + __u8 domain_bits; > > Let's add explicit padding here as well? Ok Thanks, Jean
next prev parent reply other threads:[~2018-10-12 18:54 UTC|newest] Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-10-12 14:59 [PATCH v3 0/7] Add virtio-iommu driver Jean-Philippe Brucker 2018-10-12 14:59 ` Jean-Philippe Brucker 2018-10-12 14:59 ` [PATCH v3 1/7] dt-bindings: virtio-mmio: Add IOMMU description Jean-Philippe Brucker 2018-10-12 14:59 ` Jean-Philippe Brucker 2018-10-12 14:59 ` Jean-Philippe Brucker 2018-10-18 0:30 ` Rob Herring [not found] ` <20181012145917.6840-2-jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org> 2018-10-18 0:30 ` Rob Herring 2018-10-18 0:30 ` Rob Herring 2018-11-15 8:45 ` Auger Eric 2018-11-15 8:45 ` Auger Eric 2018-10-12 14:59 ` [PATCH v3 2/7] dt-bindings: virtio: Add virtio-pci-iommu node Jean-Philippe Brucker 2018-10-12 14:59 ` Jean-Philippe Brucker 2018-10-12 14:59 ` Jean-Philippe Brucker 2018-10-18 0:35 ` Rob Herring 2018-10-18 0:35 ` Rob Herring 2018-10-18 0:35 ` Rob Herring 2018-11-15 8:45 ` Auger Eric 2018-11-15 8:45 ` Auger Eric 2018-11-15 8:45 ` Auger Eric 2018-10-12 14:59 ` [PATCH v3 3/7] PCI: OF: Allow endpoints to bypass the iommu Jean-Philippe Brucker 2018-10-12 14:59 ` Jean-Philippe Brucker 2018-10-12 14:59 ` Jean-Philippe Brucker [not found] ` <20181012145917.6840-4-jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org> 2018-10-12 19:41 ` Bjorn Helgaas 2018-10-12 19:41 ` Bjorn Helgaas 2018-10-15 10:52 ` Michael S. Tsirkin 2018-10-15 11:32 ` Robin Murphy [not found] ` <20181012194158.GX5906-1RhO1Y9PlrlHTL0Zs8A6p5iNqAH0jzoTYJqu5kTmcBRl57MIdRCFDg@public.gmane.org> 2018-10-15 10:52 ` Michael S. Tsirkin 2018-10-15 10:52 ` Michael S. Tsirkin [not found] ` <20181015065024-mutt-send-email-mst-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> 2018-10-15 19:46 ` Jean-philippe Brucker 2018-10-15 19:46 ` Jean-philippe Brucker 2018-10-17 15:14 ` Michael S. Tsirkin 2018-10-17 15:14 ` Michael S. Tsirkin 2018-10-18 10:47 ` Robin Murphy 2018-10-18 10:47 ` Robin Murphy 2018-10-18 10:47 ` Robin Murphy [not found] ` <20181017111100-mutt-send-email-mst-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> 2018-10-22 11:27 ` Jean-Philippe Brucker 2018-10-22 11:27 ` Jean-Philippe Brucker 2018-10-22 11:27 ` Jean-Philippe Brucker 2018-10-15 11:32 ` Robin Murphy 2018-10-15 11:32 ` Robin Murphy 2018-10-15 19:45 ` Jean-philippe Brucker 2018-10-15 19:45 ` Jean-philippe Brucker 2018-10-12 14:59 ` [PATCH v3 4/7] PCI: OF: Initialize dev->fwnode appropriately Jean-Philippe Brucker 2018-10-12 14:59 ` Jean-Philippe Brucker [not found] ` <20181012145917.6840-5-jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org> 2018-10-12 19:44 ` Bjorn Helgaas 2018-10-12 19:44 ` Bjorn Helgaas 2018-10-12 14:59 ` Jean-Philippe Brucker 2018-10-12 14:59 ` [PATCH v3 5/7] iommu: Add virtio-iommu driver Jean-Philippe Brucker 2018-10-12 14:59 ` Jean-Philippe Brucker 2018-10-12 16:35 ` Michael S. Tsirkin 2018-10-12 16:35 ` Michael S. Tsirkin 2018-10-12 16:35 ` Michael S. Tsirkin [not found] ` <20181012120953-mutt-send-email-mst-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> 2018-10-12 18:54 ` Jean-Philippe Brucker [this message] 2018-10-12 18:54 ` Jean-Philippe Brucker 2018-10-12 18:54 ` Jean-Philippe Brucker 2018-11-08 14:51 ` Auger Eric 2018-11-08 14:51 ` Auger Eric 2018-11-08 16:46 ` Jean-Philippe Brucker 2018-11-08 16:46 ` Jean-Philippe Brucker 2018-11-08 16:46 ` Jean-Philippe Brucker 2018-11-08 14:51 ` Auger Eric 2018-10-12 14:59 ` Jean-Philippe Brucker 2018-10-12 14:59 ` [PATCH v3 6/7] iommu/virtio: Add probe request Jean-Philippe Brucker 2018-10-12 14:59 ` Jean-Philippe Brucker 2018-10-12 16:42 ` Michael S. Tsirkin 2018-10-12 16:42 ` Michael S. Tsirkin 2018-11-08 14:48 ` Auger Eric [not found] ` <20181012145917.6840-7-jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org> 2018-11-08 14:48 ` Auger Eric 2018-11-08 14:48 ` Auger Eric [not found] ` <295d30bb-5aef-2727-01c0-ec10c7a8fa8c-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 2018-11-08 16:46 ` Jean-Philippe Brucker 2018-11-08 16:46 ` Jean-Philippe Brucker 2018-11-08 16:46 ` Jean-Philippe Brucker 2018-11-15 13:20 ` Auger Eric 2018-11-15 13:20 ` Auger Eric 2018-11-15 16:22 ` Jean-Philippe Brucker 2018-11-15 16:22 ` Jean-Philippe Brucker 2018-11-15 16:22 ` Jean-Philippe Brucker 2018-11-15 13:20 ` Auger Eric 2018-10-12 14:59 ` Jean-Philippe Brucker 2018-10-12 14:59 ` [PATCH v3 7/7] iommu/virtio: Add event queue Jean-Philippe Brucker 2018-10-12 14:59 ` Jean-Philippe Brucker 2018-10-12 14:59 ` Jean-Philippe Brucker 2018-10-12 17:00 ` [PATCH v3 0/7] Add virtio-iommu driver Michael S. Tsirkin [not found] ` <20181012145917.6840-1-jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org> 2018-10-12 17:00 ` Michael S. Tsirkin 2018-10-12 17:00 ` Michael S. Tsirkin 2018-10-12 18:55 ` Jean-Philippe Brucker [not found] ` <20181012125443-mutt-send-email-mst-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> 2018-10-12 18:55 ` Jean-Philippe Brucker 2018-10-12 18:55 ` Jean-Philippe Brucker 2018-10-16 9:25 ` Auger Eric 2018-10-16 9:25 ` Auger Eric 2018-10-16 18:44 ` Jean-Philippe Brucker 2018-10-16 18:44 ` Jean-Philippe Brucker 2018-10-16 20:31 ` Auger Eric 2018-10-16 20:31 ` Auger Eric 2018-10-17 11:54 ` Jean-Philippe Brucker 2018-10-17 11:54 ` Jean-Philippe Brucker 2018-10-17 15:23 ` Michael S. Tsirkin 2018-10-17 15:23 ` Michael S. Tsirkin 2018-10-17 15:23 ` Michael S. Tsirkin 2018-10-16 18:44 ` Jean-Philippe Brucker 2018-10-16 9:25 ` Auger Eric
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