mirror of https://github.com/xemu-project/xemu.git
![]() Both virtio-blk and virtio-scsi use virtio_queue_empty() as the loop condition in VQ handlers (virtio_blk_handle_vq, virtio_scsi_handle_cmd_vq). When a device is marked broken in virtqueue_pop, for example if a vIOMMU address translation failed, we want to break out of the loop. This fixes a hanging problem when booting a CentOS 3.10.0-862.el7.x86_64 kernel with ATS enabled: $ qemu-system-x86_64 \ ... \ -device intel-iommu,intremap=on,caching-mode=on,eim=on,device-iotlb=on \ -device virtio-scsi-pci,iommu_platform=on,ats=on,id=scsi0,bus=pci.4,addr=0x0 The dead loop happens immediately when the kernel boots and initializes the device, where virtio_scsi_data_plane_handle_cmd will not return: > ... > #13 0x00005586602b7793 in virtio_scsi_handle_cmd_vq > #14 0x00005586602b8d66 in virtio_scsi_data_plane_handle_cmd > #15 0x00005586602ddab7 in virtio_queue_notify_aio_vq > #16 0x00005586602dfc9f in virtio_queue_host_notifier_aio_poll > #17 0x00005586607885da in run_poll_handlers_once > #18 0x000055866078880e in try_poll_mode > #19 0x00005586607888eb in aio_poll > #20 0x0000558660784561 in aio_wait_bh_oneshot > #21 0x00005586602b9582 in virtio_scsi_dataplane_stop > #22 0x00005586605a7110 in virtio_bus_stop_ioeventfd > #23 0x00005586605a9426 in virtio_pci_stop_ioeventfd > #24 0x00005586605ab808 in virtio_pci_common_write > #25 0x0000558660242396 in memory_region_write_accessor > #26 0x00005586602425ab in access_with_adjusted_size > #27 0x0000558660245281 in memory_region_dispatch_write > #28 0x00005586601e008e in flatview_write_continue > #29 0x00005586601e01d8 in flatview_write > #30 0x00005586601e04de in address_space_write > #31 0x00005586601e052f in address_space_rw > #32 0x00005586602607f2 in kvm_cpu_exec > #33 0x0000558660227148 in qemu_kvm_cpu_thread_fn > #34 0x000055866078bde7 in qemu_thread_start > #35 0x00007f5784906594 in start_thread > #36 0x00007f5784639e6f in clone With this patch, virtio_queue_empty will now return 1 as soon as the vdev is marked as broken, after a "virtio: zero sized buffers are not allowed" error. To be consistent, update virtio_queue_empty_rcu as well. Signed-off-by: Fam Zheng <famz@redhat.com> Message-Id: <20180910145616.8598-2-famz@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
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accel | ||
audio | ||
backends | ||
block | ||
bsd-user | ||
capstone@22ead3e0bf | ||
chardev | ||
contrib | ||
crypto | ||
default-configs | ||
disas | ||
docs | ||
dtc@88f18909db | ||
fpu | ||
fsdev | ||
gdb-xml | ||
hw | ||
include | ||
io | ||
libdecnumber | ||
linux-headers | ||
linux-user | ||
migration | ||
nbd | ||
net | ||
pc-bios | ||
po | ||
qapi | ||
qga | ||
qobject | ||
qom | ||
replay | ||
roms | ||
scripts | ||
scsi | ||
slirp | ||
stubs | ||
target | ||
tcg | ||
tests | ||
trace | ||
ui | ||
util | ||
.dir-locals.el | ||
.editorconfig | ||
.exrc | ||
.gdbinit | ||
.gitignore | ||
.gitmodules | ||
.gitpublish | ||
.mailmap | ||
.shippable.yml | ||
.travis.yml | ||
CODING_STYLE | ||
COPYING | ||
COPYING.LIB | ||
Changelog | ||
HACKING | ||
LICENSE | ||
MAINTAINERS | ||
Makefile | ||
Makefile.objs | ||
Makefile.target | ||
README | ||
VERSION | ||
arch_init.c | ||
balloon.c | ||
block.c | ||
blockdev-nbd.c | ||
blockdev.c | ||
blockjob.c | ||
bootdevice.c | ||
bt-host.c | ||
bt-vhci.c | ||
configure | ||
cpus-common.c | ||
cpus.c | ||
device-hotplug.c | ||
device_tree.c | ||
disas.c | ||
dma-helpers.c | ||
dump.c | ||
exec.c | ||
gdbstub.c | ||
hmp-commands-info.hx | ||
hmp-commands.hx | ||
hmp.c | ||
hmp.h | ||
ioport.c | ||
iothread.c | ||
job-qmp.c | ||
job.c | ||
memory.c | ||
memory_ldst.inc.c | ||
memory_mapping.c | ||
module-common.c | ||
monitor.c | ||
numa.c | ||
os-posix.c | ||
os-win32.c | ||
qdev-monitor.c | ||
qdict-test-data.txt | ||
qemu-bridge-helper.c | ||
qemu-deprecated.texi | ||
qemu-doc.texi | ||
qemu-edid.c | ||
qemu-ga.texi | ||
qemu-img-cmds.hx | ||
qemu-img.c | ||
qemu-img.texi | ||
qemu-io-cmds.c | ||
qemu-io.c | ||
qemu-keymap.c | ||
qemu-nbd.c | ||
qemu-nbd.texi | ||
qemu-option-trace.texi | ||
qemu-options-wrapper.h | ||
qemu-options.h | ||
qemu-options.hx | ||
qemu-seccomp.c | ||
qemu-tech.texi | ||
qemu.nsi | ||
qemu.sasl | ||
qmp.c | ||
qtest.c | ||
replication.c | ||
replication.h | ||
rules.mak | ||
thunk.c | ||
tpm.c | ||
trace-events | ||
version.rc | ||
vl.c | ||
win_dump.c | ||
win_dump.h |
README
QEMU README =========== QEMU is a generic and open source machine & userspace emulator and virtualizer. QEMU is capable of emulating a complete machine in software without any need for hardware virtualization support. By using dynamic translation, it achieves very good performance. QEMU can also integrate with the Xen and KVM hypervisors to provide emulated hardware while allowing the hypervisor to manage the CPU. With hypervisor support, QEMU can achieve near native performance for CPUs. When QEMU emulates CPUs directly it is capable of running operating systems made for one machine (e.g. an ARMv7 board) on a different machine (e.g. an x86_64 PC board). QEMU is also capable of providing userspace API virtualization for Linux and BSD kernel interfaces. This allows binaries compiled against one architecture ABI (e.g. the Linux PPC64 ABI) to be run on a host using a different architecture ABI (e.g. the Linux x86_64 ABI). This does not involve any hardware emulation, simply CPU and syscall emulation. QEMU aims to fit into a variety of use cases. It can be invoked directly by users wishing to have full control over its behaviour and settings. It also aims to facilitate integration into higher level management layers, by providing a stable command line interface and monitor API. It is commonly invoked indirectly via the libvirt library when using open source applications such as oVirt, OpenStack and virt-manager. QEMU as a whole is released under the GNU General Public License, version 2. For full licensing details, consult the LICENSE file. Building ======== QEMU is multi-platform software intended to be buildable on all modern Linux platforms, OS-X, Win32 (via the Mingw64 toolchain) and a variety of other UNIX targets. The simple steps to build QEMU are: mkdir build cd build ../configure make Additional information can also be found online via the QEMU website: https://qemu.org/Hosts/Linux https://qemu.org/Hosts/Mac https://qemu.org/Hosts/W32 Submitting patches ================== The QEMU source code is maintained under the GIT version control system. git clone git://git.qemu.org/qemu.git When submitting patches, one common approach is to use 'git format-patch' and/or 'git send-email' to format & send the mail to the qemu-devel@nongnu.org mailing list. All patches submitted must contain a 'Signed-off-by' line from the author. Patches should follow the guidelines set out in the HACKING and CODING_STYLE files. Additional information on submitting patches can be found online via the QEMU website https://qemu.org/Contribute/SubmitAPatch https://qemu.org/Contribute/TrivialPatches The QEMU website is also maintained under source control. git clone git://git.qemu.org/qemu-web.git https://www.qemu.org/2017/02/04/the-new-qemu-website-is-up/ A 'git-publish' utility was created to make above process less cumbersome, and is highly recommended for making regular contributions, or even just for sending consecutive patch series revisions. It also requires a working 'git send-email' setup, and by default doesn't automate everything, so you may want to go through the above steps manually for once. For installation instructions, please go to https://github.com/stefanha/git-publish The workflow with 'git-publish' is: $ git checkout master -b my-feature $ # work on new commits, add your 'Signed-off-by' lines to each $ git publish Your patch series will be sent and tagged as my-feature-v1 if you need to refer back to it in the future. Sending v2: $ git checkout my-feature # same topic branch $ # making changes to the commits (using 'git rebase', for example) $ git publish Your patch series will be sent with 'v2' tag in the subject and the git tip will be tagged as my-feature-v2. Bug reporting ============= The QEMU project uses Launchpad as its primary upstream bug tracker. Bugs found when running code built from QEMU git or upstream released sources should be reported via: https://bugs.launchpad.net/qemu/ If using QEMU via an operating system vendor pre-built binary package, it is preferable to report bugs to the vendor's own bug tracker first. If the bug is also known to affect latest upstream code, it can also be reported via launchpad. For additional information on bug reporting consult: https://qemu.org/Contribute/ReportABug Contact ======= The QEMU community can be contacted in a number of ways, with the two main methods being email and IRC - qemu-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/qemu-devel - #qemu on irc.oftc.net Information on additional methods of contacting the community can be found online via the QEMU website: https://qemu.org/Contribute/StartHere -- End