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vfio: powerpc/spapr: Support Dynamic DMA windows

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This adds create/remove window ioctls to create and remove DMA windows.
sPAPR defines a Dynamic DMA windows capability which allows
para-virtualized guests to create additional DMA windows on a PCI bus.
The existing linux kernels use this new window to map the entire guest
memory and switch to the direct DMA operations saving time on map/unmap
requests which would normally happen in a big amounts.

This adds 2 ioctl handlers - VFIO_IOMMU_SPAPR_TCE_CREATE and
VFIO_IOMMU_SPAPR_TCE_REMOVE - to create and remove windows.
Up to 2 windows are supported now by the hardware and by this driver.

This changes VFIO_IOMMU_SPAPR_TCE_GET_INFO handler to return additional
information such as a number of supported windows and maximum number
levels of TCE tables.

DDW is added as a capability, not as a SPAPR TCE IOMMU v2 unique feature
as we still want to support v2 on platforms which cannot do DDW for
the sake of TCE acceleration in KVM (coming soon).

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
[aw: for the vfio related changes]
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Alexey Kardashevskiy 2015-06-05 16:35:26 +10:00 • committed by Michael Ellerman
parent 2157e7b82f
commit e633bc86a9
4 changed files with 273 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

61
include/uapi/linux/vfio.h
View file

@ -444,6 +444,23 @@ struct vfio_iommu_type1_dma_unmap {
/* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
/*
* The SPAPR TCE DDW info struct provides the information about
* the details of Dynamic DMA window capability.
*
* @pgsizes contains a page size bitmask, 4K/64K/16M are supported.
* @max_dynamic_windows_supported tells the maximum number of windows
* which the platform can create.
* @levels tells the maximum number of levels in multi-level IOMMU tables;
* this allows splitting a table into smaller chunks which reduces
* the amount of physically contiguous memory required for the table.
*/
struct vfio_iommu_spapr_tce_ddw_info {
__u64 pgsizes; /* Bitmap of supported page sizes */
__u32 max_dynamic_windows_supported;
__u32 levels;
};
/*
* The SPAPR TCE info struct provides the information about the PCI bus
* address ranges available for DMA, these values are programmed into
@ -454,14 +471,17 @@ struct vfio_iommu_type1_dma_unmap {
* addresses too so the window works as a filter rather than an offset
* for IOVA addresses.
*
* A flag will need to be added if other page sizes are supported,
* so as defined here, it is always 4k.
* Flags supported:
* - VFIO_IOMMU_SPAPR_INFO_DDW: informs the userspace that dynamic DMA windows
* (DDW) support is present. @ddw is only supported when DDW is present.
*/
struct vfio_iommu_spapr_tce_info {
__u32 argsz;
__u32 flags; /* reserved for future use */
__u32 flags;
#define VFIO_IOMMU_SPAPR_INFO_DDW (1 << 0) /* DDW supported */
__u32 dma32_window_start; /* 32 bit window start (bytes) */
__u32 dma32_window_size; /* 32 bit window size (bytes) */
struct vfio_iommu_spapr_tce_ddw_info ddw;
};
#define VFIO_IOMMU_SPAPR_TCE_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12)
@ -534,6 +554,41 @@ struct vfio_iommu_spapr_register_memory {
*/
#define VFIO_IOMMU_SPAPR_UNREGISTER_MEMORY _IO(VFIO_TYPE, VFIO_BASE + 18)
/**
* VFIO_IOMMU_SPAPR_TCE_CREATE - _IOWR(VFIO_TYPE, VFIO_BASE + 19, struct vfio_iommu_spapr_tce_create)
*
* Creates an additional TCE table and programs it (sets a new DMA window)
* to every IOMMU group in the container. It receives page shift, window
* size and number of levels in the TCE table being created.
*
* It allocates and returns an offset on a PCI bus of the new DMA window.
*/
struct vfio_iommu_spapr_tce_create {
__u32 argsz;
__u32 flags;
/* in */
__u32 page_shift;
__u64 window_size;
__u32 levels;
/* out */
__u64 start_addr;
};
#define VFIO_IOMMU_SPAPR_TCE_CREATE _IO(VFIO_TYPE, VFIO_BASE + 19)
/**
* VFIO_IOMMU_SPAPR_TCE_REMOVE - _IOW(VFIO_TYPE, VFIO_BASE + 20, struct vfio_iommu_spapr_tce_remove)
*
* Unprograms a TCE table from all groups in the container and destroys it.
* It receives a PCI bus offset as a window id.
*/
struct vfio_iommu_spapr_tce_remove {
__u32 argsz;
__u32 flags;
/* in */
__u64 start_addr;
};
#define VFIO_IOMMU_SPAPR_TCE_REMOVE _IO(VFIO_TYPE, VFIO_BASE + 20)
/* ***************************************************************** */
#endif /* _UAPIVFIO_H */