Re: [PATCH v6 4/4] qemu: support dirty ring feature

On Sat, Nov 20, 2021 at 03:20:48 -0500, huangy81(a)chinatelecom.cn wrote: > From: Hyman Huang(黄勇) <huangy81(a)chinatelecom.cn&gt; > > dirty ring feature was introduced in qemu-6.1, this patch add > corresponding feature named 'dirty-ring', which enable > dirty ring feature when starting vm. > > to enable the feature, libvirt add "-accel dirty-ring-size=xxx" > to QEMU command line, the following XML needs to be added to > the guest's domain description: > > <features> > <kvm> > <dirty-ring state='on' size='xxx'> > </kvm> > </features> > > if property "state=on" but property "size" not be configured, set > default ring size with 4096. > > since dirty ring can only be enabled by specifying "-accel" option > and do not support the legacy style, it seems that there's no > other way to work around this, so we use "-accel" option to specify > accelerator instead of "-machine" when building qemu commandline. > > details about the qemu "-accel" option: > https://lore.kernel.org/qemu-devel/3aa73987-40e8-3619-0723-9f17f73850bd@r... > > Signed-off-by: Hyman Huang(黄勇) <huangy81(a)chinatelecom.cn&gt; > --- > docs/formatdomain.rst | 18 ++++++++++-------- > docs/schemas/domaincommon.rng | 10 ++++++++++ > src/qemu/qemu_command.c | 6 ++++++ > 3 files changed, 26 insertions(+), 8 deletions(-) > > diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst > index eb8c973cf1..ea69b61c70 100644 > --- a/docs/formatdomain.rst > +++ b/docs/formatdomain.rst > @@ -1843,6 +1843,7 @@ Hypervisors may allow certain CPU / machine features to be toggled on/off. > <hint-dedicated state='on'/> > <poll-control state='on'/> > <pv-ipi state='off'/> > + <dirty-ring state='on' size='4096'/> > </kvm> > <xen> > <e820_host state='on'/> > @@ -1925,14 +1926,15 @@ are: > ``kvm`` > Various features to change the behavior of the KVM hypervisor. > > - ============== ============================================================================ ======= ============================ > - Feature Description Value Since > - ============== ============================================================================ ======= ============================ > - hidden Hide the KVM hypervisor from standard MSR based discovery on, off :since:`1.2.8 (QEMU 2.1.0)` > - hint-dedicated Allows a guest to enable optimizations when running on dedicated vCPUs on, off :since:`5.7.0 (QEMU 2.12.0)` > - poll-control Decrease IO completion latency by introducing a grace period of busy waiting on, off :since:`6.10.0 (QEMU 4.2)` > - pv-ipi Paravirtualized send IPIs on, off :since:`7.10.0 (QEMU 3.1)` > - ============== ============================================================================ ======= ============================ > + ============== ============================================================================ ====================================================== ============================ > + Feature Description Value Since > + ============== ============================================================================ ====================================================== ============================ > + hidden Hide the KVM hypervisor from standard MSR based discovery on, off :since:`1.2.8 (QEMU 2.1.0)` > + hint-dedicated Allows a guest to enable optimizations when running on dedicated vCPUs on, off :since:`5.7.0 (QEMU 2.12.0)` > + poll-control Decrease IO completion latency by introducing a grace period of busy waiting on, off :since:`6.10.0 (QEMU 4.2)` > + pv-ipi Paravirtualized send IPIs on, off :since:`7.10.0 (QEMU 3.1)` > + dirty-ring Enable dirty ring feature on, off; size - must be power of 2, range [1024,65536] :since:`7.10.0 (QEMU 6.1)` > + ============== ============================================================================ ====================================================== ============================ > > ``xen`` > Various features to change the behavior of the Xen hypervisor. Okay, so both hunks belong actually to the previous commit. > diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng > index f01b7a6470..5f9fe3cc58 100644 > --- a/docs/schemas/domaincommon.rng > +++ b/docs/schemas/domaincommon.rng > @@ -7212,6 +7212,16 @@ > <ref name="featurestate"/> > </element> > </optional> > + <optional> > + <element name="dirty-ring"> > + <ref name="featurestate"/> > + <optional> > + <attribute name="size"> > + <data type="unsignedInt"/> > + </attribute> > + </optional> > + </element> > + </optional> > </interleave> > </element> > </define> And this one too.

> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c > index 145596d11a..863876bfae 100644 > --- a/src/qemu/qemu_command.c > +++ b/src/qemu/qemu_command.c > @@ -7043,6 +7043,12 @@ qemuBuildAccelCommandLineKvmOptions(virCommand *cmd, > g_auto(virBuffer) buf = VIR_BUFFER_INITIALIZER; > virCommandAddArg(cmd, "-accel"); > virBufferAddLit(&buf, "kvm"); > + > + if (def->features[VIR_DOMAIN_FEATURE_KVM] == VIR_TRISTATE_SWITCH_ON && > + def->kvm_features[VIR_DOMAIN_KVM_DIRTY_RING] == VIR_TRISTATE_SWITCH_ON) { > + virBufferAsprintf(&buf, ",dirty-ring-size=%d", def->dirty_ring_size); > + } > + > virCommandAddArgBuffer(cmd, &buf); > } > } A test case is needed both for qemuxml2argvtest and qemuxml2xmltest.