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vfio: Define sparse mmap capability for regions

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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: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Williamson 2016-02-22 16:02:35 -07:00
parent d7a8d5ed87
commit ff63eb638d
1 changed files with 25 additions and 1 deletions
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26
include/uapi/linux/vfio.h
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@ -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)