[Qemu-devel] RFC: vfio API changes needed for powerpc (v3)

[Yoder Stuart-B08248]

-v3 updates
   -made vfio_pamu_attr a union, added flags
   -s/VFIO_PAMU_/VFIO_IOMMU_PAMU_/ for the ioctls to make it more
    clear which fd is being operated on
   -added flags to vfio_pamu_msi_bank_map/umap
   -VFIO_PAMU_GET_MSI_BANK_COUNT now just returns a __u32
    not a struct
   -fixed some typos

----------------------------------------------------------------------------

The Freescale PAMU is an aperture-based IOMMU with the following
characteristics.  Each device has an entry in a table in memory
describing the iova->phys mapping. The mapping has:
   -an overall aperture that is power of 2 sized, and has a start iova that
    is naturally aligned
   -has 1 or more windows within the aperture
      -number of windows must be power of 2, max is 256
      -size of each window is determined by aperture size / # of windows
      -iova of each window is determined by aperture start iova / # of windows
      -the mapped region in each window can be different than
       the window size...mapping must power of 2
      -physical address of the mapping must be naturally aligned
       with the mapping size

These ioctls operate on the VFIO file descriptor (/dev/vfio/vfio).

/*
 * VFIO_IOMMU_PAMU_GET_ATTR
 *
 * Gets the iommu attributes for the current vfio container.  This
 * ioctl is applicable to an iommu type of VFIO_PAMU only.
 * Caller sets argsz and attribute.  The ioctl fills in
 * the provided struct vfio_pamu_attr based on the attribute
 * value that was set.

 * Return: 0 on success, -errno on failure
 */
struct vfio_pamu_attr {
        __u32   argsz;
        __u32   flags;        /* no flags currently */
        __u32   attribute;

        union {
                /* VFIO_ATTR_GEOMETRY */
                struct { 
                        __u64 aperture_start; /* first addr that can be mapped 
*/
                        __u64 aperture_end;  /* last addr that can be mapped */
                } attr;
        
                /* VFIO_ATTR_WINDOWS */
                __u32 windows;  /* number of windows in the aperture */
                                /* initially this will be the max number
                                 * of windows that can be set
                                 */

                /* VFIO_ATTR_PAMU_STASH */
                struct { 
                        __u32 cpu;     /* CPU number for stashing */
                        __u32 cache;   /* cache ID for stashing */
                } stash;
        }
};
#define VFIO_IOMMU_PAMU_GET_ATTR  _IO(VFIO_TYPE, VFIO_BASE + x,
        struct vfio_pamu_attr)

/*
 * VFIO_IOMMU_PAMU_SET_ATTR
 *
 * Sets the iommu attributes for the current vfio container.  This
 * ioctl is applicable to an iommu type of VFIO_PAMU only.
 * Caller sets struct vfio_pamu attr, including argsz and attribute and
 * setting any fields that are valid for the attribute.
 * Return: 0 on success, -errno on failure
 */
#define VFIO_IOMMU_PAMU_SET_ATTR  _IO(VFIO_TYPE, VFIO_BASE + x,
        struct vfio_pamu_attr)

/*
 * VFIO_IOMMU_PAMU_GET_MSI_BANK_COUNT
 *
 * Returns the number of MSI banks for this platform.  This tells user space
 * how many aperture windows should be reserved for MSI banks when setting
 * the PAMU geometry and window count.
 * Return: __u32 bank count on success, -errno on failure
 */
#define VFIO_IOMMU_PAMU_GET_MSI_BANK_COUNT _IO(VFIO_TYPE, VFIO_BASE + x, __u32)

/*
 * VFIO_IOMMU_PAMU_MAP_MSI_BANK
 *
 * Maps the MSI bank at the specified index and iova.  User space must
 * call this ioctl once for each MSI bank (count of banks is returned by
 * VFIO_IOMMU_PAMU_GET_MSI_BANK_COUNT).
 * Caller provides struct vfio_pamu_msi_bank_map with all fields set.
 * Return: 0 on success, -errno on failure
 */

struct vfio_pamu_msi_bank_map {
        __u32   argsz;
        __u32   flags;     /* no flags currently */
        __u32   msi_bank_index;  /* the index of the MSI bank */
        __u64   iova;      /* the iova the bank is to be mapped to */
};
#define VFIO_IOMMU_PAMU_MAP_MSI_BANK  _IO(VFIO_TYPE, VFIO_BASE + x,
        struct vfio_pamu_msi_bank_map )

/*
 * VFIO_IOMMU_PAMU_UNMAP_MSI_BANK
 *
 * Unmaps the MSI bank at the specified iova.
 * Caller provides struct vfio_pamu_msi_bank_unmap with all fields set.
 * Operates on VFIO file descriptor (/dev/vfio/vfio).
 * Return: 0 on success, -errno on failure
 */

struct vfio_pamu_msi_bank_unmap {
        __u32   argsz;
        __u32   flags;     /* no flags currently */
        __u64   iova;      /* the iova to be unmapped to */
};
#define VFIO_IOMMU_PAMU_UNMAP_MSI_BANK  _IO(VFIO_TYPE, VFIO_BASE + x,
        struct vfio_pamu_msi_bank_unmap )