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Commit ff63eb63 authored by Alex Williamson's avatar Alex Williamson
Browse files

vfio: Define sparse mmap capability for regions 



We can't always support mmap across an entire device region, for
example we deny mmaps covering the MSI-X table of PCI devices, but
we don't really have a way to report it.  We expect the user to
implicitly know this restriction.  We also can't split the region
because vfio-pci defines an API with fixed region index to BAR
number mapping.  We therefore define a new capability which lists
areas within the region that may be mmap'd.  In addition to the
MSI-X case, this potentially enables in-kernel emulation and
extensions to devices.

Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent d7a8d5ed

include/uapi/linux/vfio.h

+25 −1
Original line number Diff line number Diff line
@@ -221,13 +221,37 @@ struct vfio_region_info { 
#define VFIO_REGION_INFO_FLAG_READ	(1 << 0) /* Region supports read */

#define VFIO_REGION_INFO_FLAG_WRITE	(1 << 1) /* Region supports write */

#define VFIO_REGION_INFO_FLAG_MMAP	(1 << 2) /* Region supports mmap */

#define VFIO_REGION_INFO_FLAG_CAPS	(1 << 3) /* Info supports caps */

	__u32	index;		/* Region index */

	__u32	resv;		/* Reserved for alignment */

	__u32	cap_offset;	/* Offset within info struct of first cap */

	__u64	size;		/* Region size (bytes) */

	__u64	offset;		/* Region offset from start of device fd */

};

#define VFIO_DEVICE_GET_REGION_INFO	_IO(VFIO_TYPE, VFIO_BASE + 8)



/*

 * The sparse mmap capability allows finer granularity of specifying areas

 * within a region with mmap support.  When specified, the user should only

 * mmap the offset ranges specified by the areas array.  mmaps outside of the

 * areas specified may fail (such as the range covering a PCI MSI-X table) or

 * may result in improper device behavior.

 *

 * The structures below define version 1 of this capability.

 */

#define VFIO_REGION_INFO_CAP_SPARSE_MMAP	1



struct vfio_region_sparse_mmap_area {

	__u64	offset;	/* Offset of mmap'able area within region */

	__u64	size;	/* Size of mmap'able area */

};



struct vfio_region_info_cap_sparse_mmap {

	struct vfio_info_cap_header header;

	__u32	nr_areas;

	__u32	reserved;

	struct vfio_region_sparse_mmap_area areas[];

};



/**

 * VFIO_DEVICE_GET_IRQ_INFO - _IOWR(VFIO_TYPE, VFIO_BASE + 9,

 *				    struct vfio_irq_info)