Re: [PATCH v2 13/40] vfio: Add support for Shared Virtual Addressing
From: Xu Zaibo <hidden>
Date: 2018-08-27 08:07:05
Also in:
kvm, linux-acpi, linux-arm-kernel, linux-iommu, linux-mm, linux-pci
Hi Jean, On 2018/5/12 3:06, Jean-Philippe Brucker wrote:
quoted hunk ↗ jump to hunk
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index 1aa7b82e8169..dc07752c8fe8 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h@@ -665,6 +665,82 @@ struct vfio_iommu_type1_dma_unmap { #define VFIO_IOMMU_ENABLE _IO(VFIO_TYPE, VFIO_BASE + 15) #define VFIO_IOMMU_DISABLE _IO(VFIO_TYPE, VFIO_BASE + 16) +/* + * VFIO_IOMMU_BIND_PROCESS + * + * Allocate a PASID for a process address space, and use it to attach this + * process to all devices in the container. Devices can then tag their DMA + * traffic with the returned @pasid to perform transactions on the associated + * virtual address space. Mapping and unmapping buffers is performed by standard + * functions such as mmap and malloc. + * + * If flag is VFIO_IOMMU_BIND_PID, @pid contains the pid of a foreign process to + * bind. Otherwise the current task is bound. Given that the caller owns the + * device, setting this flag grants the caller read and write permissions on the + * entire address space of foreign process described by @pid. Therefore, + * permission to perform the bind operation on a foreign process is governed by + * the ptrace access mode PTRACE_MODE_ATTACH_REALCREDS check. See man ptrace(2) + * for more information. + * + * On success, VFIO writes a Process Address Space ID (PASID) into @pasid. This + * ID is unique to a process and can be used on all devices in the container. + * + * On fork, the child inherits the device fd and can use the bonds setup by its + * parent. Consequently, the child has R/W access on the address spaces bound by + * its parent. After an execv, the device fd is closed and the child doesn't + * have access to the address space anymore. + * + * To remove a bond between process and container, VFIO_IOMMU_UNBIND ioctl is + * issued with the same parameters. If a pid was specified in VFIO_IOMMU_BIND, + * it should also be present for VFIO_IOMMU_UNBIND. Otherwise unbind the current + * task from the container. + */ +struct vfio_iommu_type1_bind_process { + __u32 flags; +#define VFIO_IOMMU_BIND_PID (1 << 0) + __u32 pasid;
As I am doing some works on the SVA patch set. I just consider why the user space need this pasid. Maybe, is it much more reasonable to set the pasid into all devices under the vfio container by a call back function from 'vfio_devices' while 'VFIO_IOMMU_BIND_PROCESS' CMD is executed in kernel land? I am not sure because there exists no suitable call back in 'vfio_device' at present. Thanks, Zaibo
+ __s32 pid;
+};
+
+/*
+ * Only mode supported at the moment is VFIO_IOMMU_BIND_PROCESS, which takes
+ * vfio_iommu_type1_bind_process in data.
+ */
+struct vfio_iommu_type1_bind {
+ __u32 argsz;
+ __u32 flags;
+#define VFIO_IOMMU_BIND_PROCESS (1 << 0)
+ __u8 data[];
+};
+
+/*
+ * VFIO_IOMMU_BIND - _IOWR(VFIO_TYPE, VFIO_BASE + 22, struct vfio_iommu_bind)
+ *
+ * Manage address spaces of devices in this container. Initially a TYPE1
+ * container can only have one address space, managed with
+ * VFIO_IOMMU_MAP/UNMAP_DMA.
+ *
+ * An IOMMU of type VFIO_TYPE1_NESTING_IOMMU can be managed by both MAP/UNMAP
+ * and BIND ioctls at the same time. MAP/UNMAP acts on the stage-2 (host) page
+ * tables, and BIND manages the stage-1 (guest) page tables. Other types of
+ * IOMMU may allow MAP/UNMAP and BIND to coexist, where MAP/UNMAP controls
+ * non-PASID traffic and BIND controls PASID traffic. But this depends on the
+ * underlying IOMMU architecture and isn't guaranteed.
+ *
+ * Availability of this feature depends on the device, its bus, the underlying
+ * IOMMU and the CPU architecture.
+ *
+ * returns: 0 on success, -errno on failure.
+ */
+#define VFIO_IOMMU_BIND _IO(VFIO_TYPE, VFIO_BASE + 22)
+
+/*
+ * VFIO_IOMMU_UNBIND - _IOWR(VFIO_TYPE, VFIO_BASE + 23, struct vfio_iommu_bind)
+ *
+ * Undo what was done by the corresponding VFIO_IOMMU_BIND ioctl.
+ */
+#define VFIO_IOMMU_UNBIND _IO(VFIO_TYPE, VFIO_BASE + 23)
+
/* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
/*