These patches aim to solve two types of DMA-reentrancy issues: 1.) mmio -> dma -> mmio case To solve this, we track whether the device is engaged in io by checking/setting a reentrancy-guard within APIs used for MMIO access.
2.) bh -> dma write -> mmio case This case is trickier, since we dont have a generic way to associate a bh with the underlying Device/DeviceState. Thus, this version allows a device to associate a reentrancy-guard with a bh, when creating it. (Instead of calling qemu_bh_new, you call qemu_bh_new_guarded) I replaced most of the qemu_bh_new invocations with the guarded analog, except for the ones where the DeviceState was not trivially accessible Unlike v3, these changes should address issues in devices that bypass DMA apis and directly call into address_space. e.g. https://gitlab.com/qemu-project/qemu/-/issues/827 v3 -> v4: Instead of changing all of the DMA APIs, instead add an optional reentrancy guard to the BH API. v2 -> v3: Bite the bullet and modify the DMA APIs, rather than attempting to guess DeviceStates in BHs. Alexander Bulekov (3): memory: prevent dma-reentracy issues async: Add an optional reentrancy guard to the BH API hw: replace most qemu_bh_new calls with qemu_bh_new_guarded Alexander Bulekov (3): memory: prevent dma-reentracy issues async: Add an optional reentrancy guard to the BH API hw: replace most qemu_bh_new calls with qemu_bh_new_guarded docs/devel/multiple-iothreads.txt | 2 ++ hw/9pfs/xen-9p-backend.c | 4 +++- hw/block/dataplane/virtio-blk.c | 3 ++- hw/block/dataplane/xen-block.c | 5 +++-- hw/block/virtio-blk.c | 5 +++-- hw/char/virtio-serial-bus.c | 3 ++- hw/display/qxl.c | 9 ++++++--- hw/display/virtio-gpu.c | 6 ++++-- hw/ide/ahci.c | 3 ++- hw/ide/core.c | 3 ++- hw/misc/imx_rngc.c | 6 ++++-- hw/misc/macio/mac_dbdma.c | 2 +- hw/net/virtio-net.c | 3 ++- hw/nvme/ctrl.c | 6 ++++-- hw/scsi/mptsas.c | 3 ++- hw/scsi/scsi-bus.c | 3 ++- hw/scsi/vmw_pvscsi.c | 3 ++- hw/usb/dev-uas.c | 3 ++- hw/usb/hcd-dwc2.c | 3 ++- hw/usb/hcd-ehci.c | 3 ++- hw/usb/hcd-uhci.c | 2 +- hw/usb/host-libusb.c | 6 ++++-- hw/usb/redirect.c | 6 ++++-- hw/usb/xen-usb.c | 3 ++- hw/virtio/virtio-balloon.c | 5 +++-- hw/virtio/virtio-crypto.c | 3 ++- include/block/aio.h | 18 ++++++++++++++++-- include/hw/qdev-core.h | 7 +++++++ include/qemu/main-loop.h | 7 +++++-- softmmu/memory.c | 15 +++++++++++++++ softmmu/trace-events | 1 + tests/unit/ptimer-test-stubs.c | 3 ++- util/async.c | 12 +++++++++++- util/main-loop.c | 5 +++-- 34 files changed, 128 insertions(+), 43 deletions(-) -- 2.39.0
