The Xen blkif protocol requires that sector based quantities should be
interpreted strictly as multiples of 512 bytes. Specifically:
"first_sect and last_sect in blkif_request_segment, as well as
sector_number in blkif_request, are always expressed in 512-byte units."
Commit fcab2b464e
"xen: add header and build dataplane/xen-block.c"
incorrectly modified behaviour to use the block device logical_block_size
property as the scale, instead of correctly shifting values by the
hardcoded BDRV_SECTOR_BITS (and hence scaling them to 512 byte units).
This patch undoes that change and restores compliance with the spec.
Furthermore, this patch also restores the original xen_disk behaviour
of advertizing a hardcoded 'sector-size' value of 512 in xenstore and
scaling 'sectors' accordingly. The realize() method is also modified to
fail if logical_block_size is set to anything other than 512.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: <20190401121719.27208-1-paul.durrant@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
149 lines
5.5 KiB
C
149 lines
5.5 KiB
C
#ifndef XEN_BLKIF_H
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#define XEN_BLKIF_H
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#include "hw/xen/io/ring.h"
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#include <xen/io/blkif.h>
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#include <xen/io/protocols.h>
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/*
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* Not a real protocol. Used to generate ring structs which contain
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* the elements common to all protocols only. This way we get a
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* compiler-checkable way to use common struct elements, so we can
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* avoid using switch(protocol) in a number of places.
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*/
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struct blkif_common_request {
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char dummy;
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};
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struct blkif_common_response {
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char dummy;
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};
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/* i386 protocol version */
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#pragma pack(push, 4)
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struct blkif_x86_32_request {
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uint8_t operation; /* BLKIF_OP_??? */
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uint8_t nr_segments; /* number of segments */
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blkif_vdev_t handle; /* only for read/write requests */
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uint64_t id; /* private guest value, echoed in resp */
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blkif_sector_t sector_number; /* start sector idx on disk (r/w only) */
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struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
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};
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struct blkif_x86_32_request_discard {
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uint8_t operation; /* BLKIF_OP_DISCARD */
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uint8_t flag; /* nr_segments in request struct */
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blkif_vdev_t handle; /* only for read/write requests */
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uint64_t id; /* private guest value, echoed in resp */
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blkif_sector_t sector_number; /* start sector idx on disk (r/w only) */
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uint64_t nr_sectors; /* # of contiguous sectors to discard */
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};
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struct blkif_x86_32_response {
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uint64_t id; /* copied from request */
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uint8_t operation; /* copied from request */
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int16_t status; /* BLKIF_RSP_??? */
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};
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typedef struct blkif_x86_32_request blkif_x86_32_request_t;
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typedef struct blkif_x86_32_response blkif_x86_32_response_t;
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#pragma pack(pop)
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/* x86_64 protocol version */
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struct blkif_x86_64_request {
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uint8_t operation; /* BLKIF_OP_??? */
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uint8_t nr_segments; /* number of segments */
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blkif_vdev_t handle; /* only for read/write requests */
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uint64_t __attribute__((__aligned__(8))) id;
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blkif_sector_t sector_number; /* start sector idx on disk (r/w only) */
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struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
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};
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struct blkif_x86_64_request_discard {
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uint8_t operation; /* BLKIF_OP_DISCARD */
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uint8_t flag; /* nr_segments in request struct */
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blkif_vdev_t handle; /* only for read/write requests */
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uint64_t __attribute__((__aligned__(8))) id;
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blkif_sector_t sector_number; /* start sector idx on disk (r/w only) */
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uint64_t nr_sectors; /* # of contiguous sectors to discard */
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};
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struct blkif_x86_64_response {
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uint64_t __attribute__((__aligned__(8))) id;
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uint8_t operation; /* copied from request */
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int16_t status; /* BLKIF_RSP_??? */
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};
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typedef struct blkif_x86_64_request blkif_x86_64_request_t;
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typedef struct blkif_x86_64_response blkif_x86_64_response_t;
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DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
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struct blkif_common_response);
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DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
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struct blkif_x86_32_response);
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DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
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struct blkif_x86_64_response);
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union blkif_back_rings {
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blkif_back_ring_t native;
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blkif_common_back_ring_t common;
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blkif_x86_32_back_ring_t x86_32_part;
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blkif_x86_64_back_ring_t x86_64_part;
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};
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typedef union blkif_back_rings blkif_back_rings_t;
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enum blkif_protocol {
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BLKIF_PROTOCOL_NATIVE = 1,
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BLKIF_PROTOCOL_X86_32 = 2,
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BLKIF_PROTOCOL_X86_64 = 3,
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};
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static inline void blkif_get_x86_32_req(blkif_request_t *dst,
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blkif_x86_32_request_t *src)
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{
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int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
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dst->operation = src->operation;
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dst->nr_segments = src->nr_segments;
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dst->handle = src->handle;
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dst->id = src->id;
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dst->sector_number = src->sector_number;
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/* Prevent the compiler from using src->... instead. */
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barrier();
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if (dst->operation == BLKIF_OP_DISCARD) {
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struct blkif_x86_32_request_discard *s = (void *)src;
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struct blkif_request_discard *d = (void *)dst;
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d->nr_sectors = s->nr_sectors;
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return;
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}
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if (n > dst->nr_segments) {
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n = dst->nr_segments;
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}
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for (i = 0; i < n; i++) {
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dst->seg[i] = src->seg[i];
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}
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}
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static inline void blkif_get_x86_64_req(blkif_request_t *dst,
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blkif_x86_64_request_t *src)
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{
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int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
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dst->operation = src->operation;
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dst->nr_segments = src->nr_segments;
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dst->handle = src->handle;
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dst->id = src->id;
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dst->sector_number = src->sector_number;
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/* Prevent the compiler from using src->... instead. */
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barrier();
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if (dst->operation == BLKIF_OP_DISCARD) {
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struct blkif_x86_64_request_discard *s = (void *)src;
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struct blkif_request_discard *d = (void *)dst;
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d->nr_sectors = s->nr_sectors;
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return;
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}
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if (n > dst->nr_segments) {
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n = dst->nr_segments;
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}
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for (i = 0; i < n; i++) {
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dst->seg[i] = src->seg[i];
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}
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}
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#define XEN_BLKIF_SECTOR_SIZE 512
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#endif /* XEN_BLKIF_H */
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