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iommufd: Add IOMMUFD_OBJ_VEVENTQ and IOMMUFD_CMD_VEVENTQ_ALLOC

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Introduce a new IOMMUFD_OBJ_VEVENTQ object for vIOMMU Event Queue that
provides user space (VMM) another FD to read the vIOMMU Events.

Allow a vIOMMU object to allocate vEVENTQs, with a condition that each
vIOMMU can only have one single vEVENTQ per type.

Add iommufd_veventq_alloc() with iommufd_veventq_ops for the new ioctl.

Link: https://patch.msgid.link/r/21acf0751dd5c93846935ee06f93b9c65eff5e04.1741719725.git.nicolinc@nvidia.com
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Nicolin Chen
2025-03-18 14:17:47 -03:00
committed by Jason Gunthorpe
parent 0507f337fc
commit e36ba5ab80
6 changed files with 384 additions and 1 deletions
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include/uapi/linux/iommufd.h
+82
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@@ -55,6 +55,7 @@ enum {
IOMMUFD_CMD_VIOMMU_ALLOC = 0x90,
IOMMUFD_CMD_VDEVICE_ALLOC = 0x91,
IOMMUFD_CMD_IOAS_CHANGE_PROCESS = 0x92,
IOMMUFD_CMD_VEVENTQ_ALLOC = 0x93,
};
/**
@@ -1014,4 +1015,85 @@ struct iommu_ioas_change_process {
#define IOMMU_IOAS_CHANGE_PROCESS \
_IO(IOMMUFD_TYPE, IOMMUFD_CMD_IOAS_CHANGE_PROCESS)
/**
* enum iommu_veventq_flag - flag for struct iommufd_vevent_header
* @IOMMU_VEVENTQ_FLAG_LOST_EVENTS: vEVENTQ has lost vEVENTs
*/
enum iommu_veventq_flag {
IOMMU_VEVENTQ_FLAG_LOST_EVENTS = (1U << 0),
};
/**
* struct iommufd_vevent_header - Virtual Event Header for a vEVENTQ Status
* @flags: Combination of enum iommu_veventq_flag
* @sequence: The sequence index of a vEVENT in the vEVENTQ, with a range of
* [0, INT_MAX] where the following index of INT_MAX is 0
*
* Each iommufd_vevent_header reports a sequence index of the following vEVENT:
* -------------------------------------------------------------------------
* | header0 {sequence=0} | data0 | header1 {sequence=1} | data1 |...| dataN |
* -------------------------------------------------------------------------
* And this sequence index is expected to be monotonic to the sequence index of
* the previous vEVENT. If two adjacent sequence indexes has a delta larger than
* 1, it means that delta - 1 number of vEVENTs has lost, e.g. two lost vEVENTs:
* -------------------------------------------------------------------------
* | ... | header3 {sequence=3} | data3 | header6 {sequence=6} | data6 | ... |
* -------------------------------------------------------------------------
* If a vEVENT lost at the tail of the vEVENTQ and there is no following vEVENT
* providing the next sequence index, an IOMMU_VEVENTQ_FLAG_LOST_EVENTS header
* would be added to the tail, and no data would follow this header:
* ---------------------------------------------------------------------------
* |..| header3 {sequence=3} | data3 | header4 {flags=LOST_EVENTS, sequence=4} |
* ---------------------------------------------------------------------------
*/
struct iommufd_vevent_header {
__u32 flags;
__u32 sequence;
};
/**
* enum iommu_veventq_type - Virtual Event Queue Type
* @IOMMU_VEVENTQ_TYPE_DEFAULT: Reserved for future use
*/
enum iommu_veventq_type {
IOMMU_VEVENTQ_TYPE_DEFAULT = 0,
};
/**
* struct iommu_veventq_alloc - ioctl(IOMMU_VEVENTQ_ALLOC)
* @size: sizeof(struct iommu_veventq_alloc)
* @flags: Must be 0
* @viommu_id: virtual IOMMU ID to associate the vEVENTQ with
* @type: Type of the vEVENTQ. Must be defined in enum iommu_veventq_type
* @veventq_depth: Maximum number of events in the vEVENTQ
* @out_veventq_id: The ID of the new vEVENTQ
* @out_veventq_fd: The fd of the new vEVENTQ. User space must close the
* successfully returned fd after using it
* @__reserved: Must be 0
*
* Explicitly allocate a virtual event queue interface for a vIOMMU. A vIOMMU
* can have multiple FDs for different types, but is confined to one per @type.
* User space should open the @out_veventq_fd to read vEVENTs out of a vEVENTQ,
* if there are vEVENTs available. A vEVENTQ will lose events due to overflow,
* if the number of the vEVENTs hits @veventq_depth.
*
* Each vEVENT in a vEVENTQ encloses a struct iommufd_vevent_header followed by
* a type-specific data structure, in a normal case:
* -------------------------------------------------------------
* || header0 | data0 | header1 | data1 | ... | headerN | dataN ||
* -------------------------------------------------------------
* unless a tailing IOMMU_VEVENTQ_FLAG_LOST_EVENTS header is logged (refer to
* struct iommufd_vevent_header).
*/
struct iommu_veventq_alloc {
__u32 size;
__u32 flags;
__u32 viommu_id;
__u32 type;
__u32 veventq_depth;
__u32 out_veventq_id;
__u32 out_veventq_fd;
__u32 __reserved;
};
#define IOMMU_VEVENTQ_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VEVENTQ_ALLOC)
#endif