By default scsi-bus.c registers vm change state handlers for SCSIDevice instances and restarts DMA when guest execution is resumed.
Unfortunately virtio-scsi with iothreads has a special ordering requirement that the core virtio code's vm change state handler runs before scsi-bus.c's vm change state handler. This patch allows SCSI busses to disable the default vm change state handler for DMA restart. The new scsi_bus_dma_restart() API allows them to manually restart DMA at a time of their choice. Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> --- include/hw/scsi/scsi.h | 5 +++++ hw/scsi/scsi-bus.c | 37 ++++++++++++++++++++++++++++++------- 2 files changed, 35 insertions(+), 7 deletions(-) diff --git a/include/hw/scsi/scsi.h b/include/hw/scsi/scsi.h index acef25faa4..e9cc563daa 100644 --- a/include/hw/scsi/scsi.h +++ b/include/hw/scsi/scsi.h @@ -120,6 +120,10 @@ struct SCSIReqOps { struct SCSIBusInfo { int tcq; int max_channel, max_target, max_lun; + + /* Will the bus call scsi_bus_dma_restart() itself? */ + bool custom_dma_restart; + int (*parse_cdb)(SCSIDevice *dev, SCSICommand *cmd, uint8_t *buf, void *hba_private); void (*transfer_data)(SCSIRequest *req, uint32_t arg); @@ -160,6 +164,7 @@ SCSIDevice *scsi_bus_legacy_add_drive(SCSIBus *bus, BlockBackend *blk, const char *serial, Error **errp); void scsi_bus_legacy_handle_cmdline(SCSIBus *bus); void scsi_legacy_handle_cmdline(void); +void scsi_bus_dma_restart(SCSIBus *bus); SCSIRequest *scsi_req_alloc(const SCSIReqOps *reqops, SCSIDevice *d, uint32_t tag, uint32_t lun, void *hba_private); diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c index c480553083..d2c5a1652b 100644 --- a/hw/scsi/scsi-bus.c +++ b/hw/scsi/scsi-bus.c @@ -134,6 +134,27 @@ void scsi_req_retry(SCSIRequest *req) req->retry = true; } +static void scsi_device_dma_restart(SCSIDevice *dev) +{ + if (!dev->bh) { + AioContext *ctx = blk_get_aio_context(dev->conf.blk); + dev->bh = aio_bh_new(ctx, scsi_dma_restart_bh, dev); + qemu_bh_schedule(dev->bh); + } +} + +void scsi_bus_dma_restart(SCSIBus *bus) +{ + BusChild *kid; + + QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) { + DeviceState *qdev = kid->child; + SCSIDevice *dev = SCSI_DEVICE(qdev); + + scsi_device_dma_restart(dev); + } +} + static void scsi_dma_restart_cb(void *opaque, int running, RunState state) { SCSIDevice *s = opaque; @@ -141,11 +162,8 @@ static void scsi_dma_restart_cb(void *opaque, int running, RunState state) if (!running) { return; } - if (!s->bh) { - AioContext *ctx = blk_get_aio_context(s->conf.blk); - s->bh = aio_bh_new(ctx, scsi_dma_restart_bh, s); - qemu_bh_schedule(s->bh); - } + + scsi_device_dma_restart(s); } static void scsi_qdev_realize(DeviceState *qdev, Error **errp) @@ -206,8 +224,13 @@ static void scsi_qdev_realize(DeviceState *qdev, Error **errp) error_propagate(errp, local_err); return; } - dev->vmsentry = qemu_add_vm_change_state_handler(scsi_dma_restart_cb, - dev); + + if (bus->info->custom_dma_restart) { + dev->vmsentry = NULL; + } else { + dev->vmsentry = qemu_add_vm_change_state_handler(scsi_dma_restart_cb, + dev); + } } static void scsi_qdev_unrealize(DeviceState *qdev, Error **errp) -- 2.21.0