Re: [PATCH v2 13/40] vfio: Add support for Shared Virtual Addressing

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Hi,

On 2018/5/12 3:06, Jean-Philippe Brucker wrote:
Add two new ioctls for VFIO containers. VFIO_IOMMU_BIND_PROCESS creates a
bond between a container and a process address space, identified by a
Process Address Space ID (PASID). Devices in the container append this
PASID to DMA transactions in order to access the process' address space.
The process page tables are shared with the IOMMU, and mechanisms such as
PCI ATS/PRI are used to handle faults. VFIO_IOMMU_UNBIND_PROCESS removes a
bond created with VFIO_IOMMU_BIND_PROCESS.

Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>






+static int vfio_iommu_bind_group(struct vfio_iommu *iommu,
+				 struct vfio_group *group,
+				 struct vfio_mm *vfio_mm)
+{
+	int ret;
+	bool enabled_sva = false;
+	struct vfio_iommu_sva_bind_data data = {
+		.vfio_mm	= vfio_mm,
+		.iommu		= iommu,
+		.count		= 0,
+	};
+
+	if (!group->sva_enabled) {
+		ret = iommu_group_for_each_dev(group->iommu_group, NULL,
+					       vfio_iommu_sva_init);
Do we need to do *sva_init here or do anything to avoid repeated initiation?
while another process already did initiation at this device, I think that current process will get an EEXIST.

Thanks.
+		if (ret)
+			return ret;
+
+		group->sva_enabled = enabled_sva = true;
+	}
+
+	ret = iommu_group_for_each_dev(group->iommu_group, &data,
+				       vfio_iommu_sva_bind_dev);
+	if (ret && data.count > 1)
+		iommu_group_for_each_dev(group->iommu_group, vfio_mm,
+					 vfio_iommu_sva_unbind_dev);
+	if (ret && enabled_sva) {
+		iommu_group_for_each_dev(group->iommu_group, NULL,
+					 vfio_iommu_sva_shutdown);
+		group->sva_enabled = false;
+	}
+
+	return ret;
+}


@@ -1442,6 +1636,10 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
  	if (ret)
  		goto out_detach;
+ ret = vfio_iommu_replay_bind(iommu, group);
+	if (ret)
+		goto out_detach;
+
  	if (resv_msi) {
  		ret = iommu_get_msi_cookie(domain->domain, resv_msi_base);
  		if (ret)
@@ -1547,6 +1745,11 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
  			continue;
iommu_detach_group(domain->domain, iommu_group);
+		if (group->sva_enabled) {
+			iommu_group_for_each_dev(iommu_group, NULL,
+						 vfio_iommu_sva_shutdown);
+			group->sva_enabled = false;
+		}
Here, why shut down here? If another process is working on the device, there may be a crash?

Thanks.
  		list_del(&group->next);
  		kfree(group);
  		/*
@@ -1562,6 +1765,7 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,



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