Re: [libvirt] [PATCH 6/7] qemu: Support newer ivshmem device variants

QEMU added support for ivshmem-plain and ivshmem-doorbell. Those are reworked varians of legacy ivshmem that are compatible from the guest POV, but not from host's POV and have sane specification and handling. Details about the newer device type can be found in qemu's commit 5400c02b90bb: http://git.qemu.org/?p=qemu.git;a=commit;h=5400c02b90bb Signed-off-by: Martin Kletzander <mkletzan(a)redhat.com&gt; --- docs/formatdomain.html.in | 5 +- src/qemu/qemu_command.c | 109 ++++++++++++++++++++- src/qemu/qemu_command.h | 10 ++ .../qemuxml2argv-shmem-plain-doorbell.args | 46 +++++++++ .../qemuxml2argv-shmem-plain-doorbell.xml | 1 + tests/qemuxml2argvtest.c | 3 + 6 files changed, 172 insertions(+), 2 deletions(-) create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-shmem-plain-doorbell.args create mode 120000 tests/qemuxml2argvdata/qemuxml2argv-shmem-plain-doorbell.xml diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index b9163584d9f5..c614caf5f47f 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -6740,7 +6740,10 @@ qemu-kvm -net nic,model=? /dev/null <p> A shared memory device allows to share a memory region between - different virtual machines and the host. + different virtual machines and the host. Note that memory in + this region will be migrated, if that's not desired, the device + needs to be unplugged before migration and plugged back again + after that. <span class="since">Since 1.2.10, QEMU and KVM only</span> </p> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 2130a7e2e8cf..3f7dfc4a46b9 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -8550,6 +8550,44 @@ qemuBuildShmemDevLegacyStr(virDomainDefPtr def, return NULL; } +char * +qemuBuildShmemDevStr(virDomainDefPtr def, + virDomainShmemDefPtr shmem, + virQEMUCapsPtr qemuCaps) +{ + virBuffer buf = VIR_BUFFER_INITIALIZER; + + if (shmem->server.enabled) { + virBufferAddLit(&buf, "ivshmem-doorbell"); + virBufferAsprintf(&buf, ",id=%s,chardev=char%s", + shmem->info.alias, shmem->info.alias); + if (shmem->msi.vectors) + virBufferAsprintf(&buf, ",vectors=%u", shmem->msi.vectors); + if (shmem->msi.ioeventfd) + virBufferAsprintf(&buf, ",ioeventfd=%s", + virTristateSwitchTypeToString(shmem->msi.ioeventfd)); + } else { + virBufferAddLit(&buf, "ivshmem-plain"); + virBufferAsprintf(&buf, ",id=%s,memdev=shmmem-%s", + shmem->info.alias, shmem->info.alias); + + /* For now we default to master=on, users are adviced to + * unplug the ivshmem if they don't want to migrate the data + * in the shmem (see docs). */ + virBufferAddLit(&buf, ",master=on"); + } + + if (qemuBuildDeviceAddressStr(&buf, def, &shmem->info, qemuCaps) < 0) { + virBufferFreeAndReset(&buf); + return NULL; + } + + if (virBufferCheckError(&buf) < 0) + return NULL; + + return virBufferContentAndReset(&buf); +}

@@ -8579,6 +8662,18 @@ qemuBuildShmemCommandLine(virLogManagerPtr logManager, virQEMUCapsPtr qemuCaps) { char *devstr = NULL; + bool legacy = false; + + if (!qemuDomainSupportsNonLegacyShmem(qemuCaps, shmem)) { + if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_IVSHMEM)) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("shmem device is not supported with this " + "QEMU binary")); + return -1; + } + + legacy = true; + } if (shmem->size) { /* @@ -8606,8 +8701,14 @@ qemuBuildShmemCommandLine(virLogManagerPtr logManager, return -1; } - if (!(devstr = qemuBuildShmemDevLegacyStr(def, shmem, qemuCaps))) + if (legacy) + devstr = qemuBuildShmemDevLegacyStr(def, shmem, qemuCaps); + else + devstr = qemuBuildShmemDevStr(def, shmem, qemuCaps);