diff options
| author | Julien Grall | 2015-05-05 16:25:56 +0100 |
|---|---|---|
| committer | David Vrabel | 2015-10-23 14:20:40 +0100 |
| commit | 67de5dfbc176ea86ab0278658b5d55f64207ff2d (patch) | |
| tree | 0c03545ee47352eddd9b61171546a1e76fccb73c /drivers/block/xen-blkback/common.h | |
| parent | c004a6fe0c405e2aa91b2a88aa1428724e6d06f6 (diff) | |
block/xen-blkback: Make it running on 64KB page granularity
The PV block protocol is using 4KB page granularity. The goal of this
patch is to allow a Linux using 64KB page granularity behaving as a
block backend on a non-modified Xen.
It's only necessary to adapt the ring size and the number of request per
indirect frames. The rest of the code is relying on the grant table
code.
Note that the grant table code is allocating a Linux page per grant
which will result to waste 6OKB for every grant when Linux is using 64KB
page granularity. This could be improved by sharing the page between
multiple grants.
Signed-off-by: Julien Grall <julien.grall@citrix.com>
Acked-by: "Roger Pau Monné" <roger.pau@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Diffstat (limited to 'drivers/block/xen-blkback/common.h')
| -rw-r--r-- | drivers/block/xen-blkback/common.h | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h index 45a044a53d1e..68e87a037b99 100644 --- a/drivers/block/xen-blkback/common.h +++ b/drivers/block/xen-blkback/common.h @@ -39,6 +39,7 @@ #include <asm/pgalloc.h> #include <asm/hypervisor.h> #include <xen/grant_table.h> +#include <xen/page.h> #include <xen/xenbus.h> #include <xen/interface/io/ring.h> #include <xen/interface/io/blkif.h> @@ -51,12 +52,20 @@ extern unsigned int xen_blkif_max_ring_order; */ #define MAX_INDIRECT_SEGMENTS 256 -#define SEGS_PER_INDIRECT_FRAME \ - (PAGE_SIZE/sizeof(struct blkif_request_segment)) +/* + * Xen use 4K pages. The guest may use different page size (4K or 64K) + * Number of Xen pages per segment + */ +#define XEN_PAGES_PER_SEGMENT (PAGE_SIZE / XEN_PAGE_SIZE) + +#define XEN_PAGES_PER_INDIRECT_FRAME \ + (XEN_PAGE_SIZE/sizeof(struct blkif_request_segment)) +#define SEGS_PER_INDIRECT_FRAME \ + (XEN_PAGES_PER_INDIRECT_FRAME / XEN_PAGES_PER_SEGMENT) + #define MAX_INDIRECT_PAGES \ ((MAX_INDIRECT_SEGMENTS + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME) -#define INDIRECT_PAGES(_segs) \ - ((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME) +#define INDIRECT_PAGES(_segs) DIV_ROUND_UP(_segs, XEN_PAGES_PER_INDIRECT_FRAME) /* Not a real protocol. Used to generate ring structs which contain * the elements common to all protocols only. This way we get a |