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virtio-blk: add SGI_IO passthru support 

[had the qemu list address wrong the first time, reply to this message,
 not the previous if you were on Cc]

Add support for SG_IO passthru (packet commands) to the virtio-blk
backend.  Conceptually based on an older patch from Hannes Reinecke
but largely rewritten to match the code structure and layering in
virtio-blk.

Note that currently we issue the hose SG_IO synchronously.  We could
easily switch to async I/O, but that would required either bloating
the VirtIOBlockReq by the size of struct sg_io_hdr or an additional
memory allocation for each SG_IO request.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Christoph Hellwig 2009-04-27 10:29:14 +02:00 committed by Anthony Liguori
parent 451c4abd8c
commit 1063b8b15f
2 changed files with 128 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

123
hw/virtio-blk.c
View File

@ -15,6 +15,9 @@
#include <sysemu.h>
#include "virtio-blk.h"
#include "block_int.h"
#ifdef __linux__
# include <scsi/sg.h>
#endif
typedef struct VirtIOBlock
{
@ -35,6 +38,7 @@ typedef struct VirtIOBlockReq
VirtQueueElement elem;
struct virtio_blk_inhdr *in;
struct virtio_blk_outhdr *out;
struct virtio_scsi_inhdr *scsi;
QEMUIOVector qiov;
struct VirtIOBlockReq *next;
} VirtIOBlockReq;
@ -103,6 +107,108 @@ static VirtIOBlockReq *virtio_blk_get_request(VirtIOBlock *s)
return req;
}
#ifdef __linux__
static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
{
struct sg_io_hdr hdr;
int ret, size = 0;
int status;
int i;
/*
* We require at least one output segment each for the virtio_blk_outhdr
* and the SCSI command block.
*
* We also at least require the virtio_blk_inhdr, the virtio_scsi_inhdr
* and the sense buffer pointer in the input segments.
*/
if (req->elem.out_num < 2 || req->elem.in_num < 3) {
virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
return;
}
/*
* No support for bidirection commands yet.
*/
if (req->elem.out_num > 2 && req->elem.in_num > 3) {
virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
return;
}
/*
* The scsi inhdr is placed in the second-to-last input segment, just
* before the regular inhdr.
*/
req->scsi = (void *)req->elem.in_sg[req->elem.in_num - 2].iov_base;
size = sizeof(*req->in) + sizeof(*req->scsi);
memset(&hdr, 0, sizeof(struct sg_io_hdr));
hdr.interface_id = 'S';
hdr.cmd_len = req->elem.out_sg[1].iov_len;
hdr.cmdp = req->elem.out_sg[1].iov_base;
hdr.dxfer_len = 0;
if (req->elem.out_num > 2) {
/*
* If there are more than the minimally required 2 output segments
* there is write payload starting from the third iovec.
*/
hdr.dxfer_direction = SG_DXFER_TO_DEV;
hdr.iovec_count = req->elem.out_num - 2;
for (i = 0; i < hdr.iovec_count; i++)
hdr.dxfer_len += req->elem.out_sg[i + 2].iov_len;
hdr.dxferp = req->elem.out_sg + 2;
} else if (req->elem.in_num > 3) {
/*
* If we have more than 3 input segments the guest wants to actually
* read data.
*/
hdr.dxfer_direction = SG_DXFER_FROM_DEV;
hdr.iovec_count = req->elem.in_num - 3;
for (i = 0; i < hdr.iovec_count; i++)
hdr.dxfer_len += req->elem.in_sg[i].iov_len;
hdr.dxferp = req->elem.in_sg;
size += hdr.dxfer_len;
} else {
/*
* Some SCSI commands don't actually transfer any data.
*/
hdr.dxfer_direction = SG_DXFER_NONE;
}
hdr.sbp = req->elem.in_sg[req->elem.in_num - 3].iov_base;
hdr.mx_sb_len = req->elem.in_sg[req->elem.in_num - 3].iov_len;
size += hdr.mx_sb_len;
ret = bdrv_ioctl(req->dev->bs, SG_IO, &hdr);
if (ret) {
status = VIRTIO_BLK_S_UNSUPP;
hdr.status = ret;
hdr.resid = hdr.dxfer_len;
} else if (hdr.status) {
status = VIRTIO_BLK_S_IOERR;
} else {
status = VIRTIO_BLK_S_OK;
}
req->scsi->errors = hdr.status;
req->scsi->residual = hdr.resid;
req->scsi->sense_len = hdr.sb_len_wr;
req->scsi->data_len = hdr.dxfer_len;
virtio_blk_req_complete(req, status);
}
#else
static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
{
virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
}
#endif /* __linux__ */
static void virtio_blk_handle_write(VirtIOBlockReq *req)
{
bdrv_aio_writev(req->dev->bs, req->out->sector, &req->qiov,
@ -136,12 +242,7 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base;
if (req->out->type & VIRTIO_BLK_T_SCSI_CMD) {
unsigned int len = sizeof(*req->in);
req->in->status = VIRTIO_BLK_S_UNSUPP;
virtqueue_push(vq, &req->elem, len);
virtio_notify(vdev, vq);
qemu_free(req);
virtio_blk_handle_scsi(req);
} else if (req->out->type & VIRTIO_BLK_T_OUT) {
qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],
req->elem.out_num - 1);
@ -203,7 +304,15 @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)
static uint32_t virtio_blk_get_features(VirtIODevice *vdev)
{
return (1 << VIRTIO_BLK_F_SEG_MAX | 1 << VIRTIO_BLK_F_GEOMETRY);
uint32_t features = 0;
features |= (1 << VIRTIO_BLK_F_SEG_MAX);
features |= (1 << VIRTIO_BLK_F_GEOMETRY);
#ifdef __linux__
features |= (1 << VIRTIO_BLK_F_SCSI);
#endif
return features;
}
static void virtio_blk_save(QEMUFile *f, void *opaque)

12
hw/virtio-blk.h
View File

@ -28,6 +28,9 @@
#define VIRTIO_BLK_F_SIZE_MAX 1 /* Indicates maximum segment size */
#define VIRTIO_BLK_F_SEG_MAX 2 /* Indicates maximum # of segments */
#define VIRTIO_BLK_F_GEOMETRY 4 /* Indicates support of legacy geometry */
#define VIRTIO_BLK_F_RO 5 /* Disk is read-only */
#define VIRTIO_BLK_F_BLK_SIZE 6 /* Block size of disk is available*/
#define VIRTIO_BLK_F_SCSI 7 /* Supports scsi command passthru */
struct virtio_blk_config
{
@ -70,6 +73,15 @@ struct virtio_blk_inhdr
unsigned char status;
};
/* SCSI pass-through header */
struct virtio_scsi_inhdr
{
uint32_t errors;
uint32_t data_len;
uint32_t sense_len;
uint32_t residual;
};
void *virtio_blk_init(PCIBus *bus, BlockDriverState *bs);
#endif