On 2021-06-29 18:34, Will Deacon wrote:

On Fri, Jun 18, 2021 at 05:24:49PM +0100, Robin Murphy wrote:

quoted

Arm Fast Models are still implementing legacy virtio-pci devices behind
the SMMU, which continue to be problematic as "real hardware" devices
(from the point of view of the simulated system) without the mitigating
VIRTIO_F_ACCESS_PLATFORM feature.

Since we now have the ability to force passthrough on a device-specific
basis, let's use it to work around this particular oddity so that people
who just want to boot Linux on a model don't have to fiddle around with
things to avoid the SMMU getting in the way by default (and I don't have
to keep telling them which things...)

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 15 +++++++++++++++
  1 file changed, 15 insertions(+)

Any chance of getting the fastmodels updated instead? It feels like it
has to happen *eventually*, and then there would be no need for this bodge.

If it's any consolation the JIRA ticket you raised in 2017 is still open...

Robin.

Will

quoted

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 54b2f27b81d4..13cf16e8f45b 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -2649,6 +2649,20 @@ static int arm_smmu_dev_disable_feature(struct device *dev,
  	}
  }
  
+static int arm_smmu_def_domain_type(struct device *dev)
+{
+	if (dev_is_pci(dev)) {
+		struct pci_dev *pdev = to_pci_dev(dev);
+
+		/* Legacy virtio-block devices on Arm Fast Models */
+		if (pdev->vendor == 0x1af4 && pdev->device == 0x1001 &&
+		    pdev->subsystem_vendor == 0x00ff && pdev->subsystem_device == 0x0002)
+			return IOMMU_DOMAIN_IDENTITY;
+	}
+
+	return 0;
+}
+
  static struct iommu_ops arm_smmu_ops = {
  	.capable		= arm_smmu_capable,
  	.domain_alloc		= arm_smmu_domain_alloc,

@@ -2673,6 +2687,7 @@ static struct iommu_ops arm_smmu_ops = {
  	.sva_bind		= arm_smmu_sva_bind,
  	.sva_unbind		= arm_smmu_sva_unbind,
  	.sva_get_pasid		= arm_smmu_sva_get_pasid,
+	.def_domain_type	= arm_smmu_def_domain_type,
  	.pgsize_bitmap		= -1UL, /* Restricted during device attach */
  	.owner			= THIS_MODULE,
  };

-- 
2.25.1

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