Scatter/gather functionality uses the newly added DMA helpers. The device can choose between doing DMA itself, or calling scsi_req_data as usual, which will use the newly added DMA helpers to copy piecewise to/from the destination area(s).
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> --- hw/scsi-bus.c | 28 ++++++++++++++++++++++++++-- hw/scsi.h | 3 +++ 2 files changed, 29 insertions(+), 2 deletions(-) diff --git a/hw/scsi-bus.c b/hw/scsi-bus.c index aa811f4..b774261 100644 --- a/hw/scsi-bus.c +++ b/hw/scsi-bus.c @@ -5,6 +5,7 @@ #include "qdev.h" #include "blockdev.h" #include "trace.h" +#include "dma.h" static char *scsibus_get_fw_dev_path(DeviceState *dev); static int scsi_req_parse(SCSICommand *cmd, SCSIDevice *dev, uint8_t *buf); @@ -632,6 +633,11 @@ int32_t scsi_req_enqueue(SCSIRequest *req) assert(!req->enqueued); scsi_req_ref(req); + if (req->bus->info->get_sg_list) { + req->sg = req->bus->info->get_sg_list(req); + } else { + req->sg = NULL; + } req->enqueued = true; QTAILQ_INSERT_TAIL(&req->dev->requests, req, next); @@ -1256,14 +1262,32 @@ void scsi_req_continue(SCSIRequest *req) Once it completes, calling scsi_req_continue will restart I/O. */ void scsi_req_data(SCSIRequest *req, int len) { + uint8_t *buf; if (req->io_canceled) { trace_scsi_req_data_canceled(req->dev->id, req->lun, req->tag, len); return; } trace_scsi_req_data(req->dev->id, req->lun, req->tag, len); assert(req->cmd.mode != SCSI_XFER_NONE); - req->resid -= len; - req->bus->info->transfer_data(req, len); + if (!req->sg) { + req->resid -= len; + req->bus->info->transfer_data(req, len); + return; + } + + /* If the device calls scsi_req_data and the HBA specified a + * scatter/gather list, the transfer has to happen in a single + * step. */ + assert(!req->dma_started); + req->dma_started = true; + + buf = scsi_req_get_buf(req); + if (req->cmd.mode == SCSI_XFER_FROM_DEV) { + req->resid = dma_buf_read(buf, len, req->sg); + } else { + req->resid = dma_buf_write(buf, len, req->sg); + } + scsi_req_continue(req); } void scsi_req_print(SCSIRequest *req) diff --git a/hw/scsi.h b/hw/scsi.h index 27ca087..5b1ca60 100644 --- a/hw/scsi.h +++ b/hw/scsi.h @@ -50,6 +50,8 @@ struct SCSIRequest { size_t resid; SCSICommand cmd; BlockDriverAIOCB *aiocb; + QEMUSGList *sg; + bool dma_started; uint8_t sense[SCSI_SENSE_BUF_SIZE]; uint32_t sense_len; bool enqueued; @@ -110,6 +112,7 @@ struct SCSIBusInfo { void (*transfer_data)(SCSIRequest *req, uint32_t arg); void (*complete)(SCSIRequest *req, uint32_t arg, int32_t len); void (*cancel)(SCSIRequest *req); + QEMUSGList *(*get_sg_list)(SCSIRequest *req); }; struct SCSIBus { -- 1.7.7.1