This patch adds a pair of new ioctl commands to communicate with user space (virtual machine hypervisor) to get and set VMID that indicates a Virtual Machine Identifier, being used by some IOMMU to tag TLB entries -- similar to CPU MMU, using this VMID number allows IOMMU to invalidate at the same time TLBs of the same VM.
Signed-off-by: Nicolin Chen <[email protected]> --- drivers/vfio/vfio.c | 13 +++++++++++++ include/uapi/linux/vfio.h | 26 ++++++++++++++++++++++++++ 2 files changed, 39 insertions(+) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 3c034fe14ccb..c17b25c127a2 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -59,6 +59,7 @@ struct vfio_container { struct rw_semaphore group_lock; struct vfio_iommu_driver *iommu_driver; void *iommu_data; + u32 vmid; bool noiommu; }; @@ -1190,6 +1191,16 @@ static long vfio_fops_unl_ioctl(struct file *filep, case VFIO_SET_IOMMU: ret = vfio_ioctl_set_iommu(container, arg); break; + case VFIO_IOMMU_GET_VMID: + ret = copy_to_user((void __user *)arg, &container->vmid, + sizeof(u32)) ? -EFAULT : 0; + break; + case VFIO_IOMMU_SET_VMID: + if ((u32)arg == VFIO_IOMMU_VMID_INVALID) + return -EINVAL; + container->vmid = (u32)arg; + ret = 0; + break; default: driver = container->iommu_driver; data = container->iommu_data; @@ -1213,6 +1224,8 @@ static int vfio_fops_open(struct inode *inode, struct file *filep) init_rwsem(&container->group_lock); kref_init(&container->kref); + container->vmid = VFIO_IOMMU_VMID_INVALID; + filep->private_data = container; return 0; diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index ef33ea002b0b..58c5fa6aaca6 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -1216,6 +1216,32 @@ struct vfio_iommu_type1_dirty_bitmap_get { #define VFIO_IOMMU_DIRTY_PAGES _IO(VFIO_TYPE, VFIO_BASE + 17) +/** + * VFIO_IOMMU_GET_VMID - _IOWR(VFIO_TYPE, VFIO_BASE + 22, __u32 *vmid) + * VFIO_IOMMU_SET_VMID - _IOWR(VFIO_TYPE, VFIO_BASE + 23, __u32 vmid) + * + * IOCTLs are used for VMID alignment between Kernel and User Space hypervisor. + * In a virtualization use case, a guest owns the first stage translation, and + * the hypervisor owns the second stage translation. VMID is an Virtual Machine + * Identifier that is to tag TLB entries of a VM. If a VM has multiple physical + * devices being assigned to it, while these devices are under different IOMMU + * domains, the VMIDs in the second stage configurations of these IOMMU domains + * could be aligned to a unified VMID value. This could be achieved by using + * these two IOCTLs. + * + * Caller should get VMID upon its initial value when the first physical device + * is assigned to the VM. + * + * Caller then should set VMID to share the same VMID value with other physical + * devices being assigned to the same VM. + * + */ +#define VFIO_IOMMU_VMID_INVALID (-1U) + +#define VFIO_IOMMU_GET_VMID _IO(VFIO_TYPE, VFIO_BASE + 22) + +#define VFIO_IOMMU_SET_VMID _IO(VFIO_TYPE, VFIO_BASE + 23) + /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */ /* -- 2.17.1 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
