[PATCH v3 3/3] qemu: suppor dirty ring feature
Han Han
hhan at redhat.com
Wed Jan 13 13:32:24 UTC 2021
On Wed, Jan 13, 2021 at 1:09 AM <huangy81 at chinatelecom.cn> wrote:
> From: Hyman <huangy81 at chinatelecom.cn>
>
> QEMU introduced a dirty ring feature, this patch add a new
> KVM feature 'dirty-ring' to set this feature for kvm guests.
>
> To enable the feature, libvirt add "-accel dirty-gfn-count=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>
>
> Signed-off-by: Hyman <huangy81 at chinatelecom.cn>
> ---
> docs/formatdomain.rst | 16 +++++++++-------
> docs/schemas/domaincommon.rng | 10 ++++++++++
> src/conf/domain_conf.c | 34 ++++++++++++++++++++++++++++++++++
> src/conf/domain_conf.h | 4 ++++
> src/qemu/qemu_command.c | 13 ++++++++++---
> 5 files changed, 67 insertions(+), 10 deletions(-)
>
> diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
> index 6100b88..5bf8517 100644
> --- a/docs/formatdomain.rst
> +++ b/docs/formatdomain.rst
> @@ -1767,6 +1767,7 @@ Hypervisors may allow certain CPU / machine features
> to be toggled on/off.
> <hidden state='on'/>
> <hint-dedicated state='on'/>
> <poll-control='on'/>
> + <dirty-ring state='on' size='4096'/>
> </kvm>
> <xen>
> <e820_host state='on'/>
> @@ -1849,13 +1850,14 @@ 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)`
> - ==============
> ============================================================================
> ======= ============================
> + ==============
> ============================================================================
> ================================== ============================
> + 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)`
> + dirty-ring Enable dirty ring feature
> on, off; size - must be power of 2 :since:`7.0.0
> (QEMU 5.2.1)`
>
Are you sure it will be added in QEMU 5.2.1 ?
I find it has been not merged in qemu yet
> + ==============
> ============================================================================
> ================================== ============================
>
> ``xen``
> Various features to change the behavior of the Xen hypervisor.
> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
> index 7dc419b..5af4bbe 100644
> --- a/docs/schemas/domaincommon.rng
> +++ b/docs/schemas/domaincommon.rng
> @@ -6569,6 +6569,16 @@
> <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>
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 349fc28..e617b95 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -186,6 +186,7 @@ VIR_ENUM_IMPL(virDomainKVM,
> "hidden",
> "hint-dedicated",
> "poll-control",
> + "dirty-ring",
> );
>
> VIR_ENUM_IMPL(virDomainXen,
> @@ -18379,6 +18380,7 @@ virDomainFeaturesDefParse(virDomainDefPtr def,
> if (def->features[VIR_DOMAIN_FEATURE_KVM] == VIR_TRISTATE_SWITCH_ON) {
> int feature;
> int value;
> + node = ctxt->node;
> if ((n = virXPathNodeSet("./features/kvm/*", ctxt, &nodes)) < 0)
> return -1;
>
> @@ -18395,6 +18397,7 @@ virDomainFeaturesDefParse(virDomainDefPtr def,
> case VIR_DOMAIN_KVM_HIDDEN:
> case VIR_DOMAIN_KVM_DEDICATED:
> case VIR_DOMAIN_KVM_POLLCONTROL:
> + case VIR_DOMAIN_KVM_DIRTY_RING:
> if (!(tmp = virXMLPropString(nodes[i], "state"))) {
> virReportError(VIR_ERR_XML_ERROR,
> _("missing 'state' attribute for "
> @@ -18413,6 +18416,26 @@ virDomainFeaturesDefParse(virDomainDefPtr def,
>
> VIR_FREE(tmp);
> def->kvm_features[feature] = value;
> +
> + /* only for dirty ring case */
> + if (((virDomainKVM) feature) ==
> VIR_DOMAIN_KVM_DIRTY_RING &&
> + value == VIR_TRISTATE_SWITCH_ON) {
> + ctxt->node = nodes[i];
> + if (virXPathUInt("string(./@size)", ctxt,
> + &def->dirty_gfn_count) < 0) {
> + virReportError(VIR_ERR_XML_ERROR, "%s",
> + _("invalid number of dirty
> GFNs"));
> + return -1;
> + }
> +
> + if ((def->dirty_gfn_count & (def->dirty_gfn_count
> - 1)) ||
> + def->dirty_gfn_count > 65536) {
> + virReportError(VIR_ERR_XML_ERROR, "%s",
> + _("max number of dirty GFNs is
> 65536 "
> + "and must be power of 2"));
> + return -1;
> + }
> + }
> break;
>
> /* coverity[dead_error_begin] */
> @@ -18421,6 +18444,7 @@ virDomainFeaturesDefParse(virDomainDefPtr def,
> }
> }
> VIR_FREE(nodes);
> + ctxt->node = node;
> }
>
> if (def->features[VIR_DOMAIN_FEATURE_XEN] == VIR_TRISTATE_SWITCH_ON) {
> @@ -22521,6 +22545,7 @@
> virDomainDefFeaturesCheckABIStability(virDomainDefPtr src,
> case VIR_DOMAIN_KVM_HIDDEN:
> case VIR_DOMAIN_KVM_DEDICATED:
> case VIR_DOMAIN_KVM_POLLCONTROL:
> + case VIR_DOMAIN_KVM_DIRTY_RING:
> if (src->kvm_features[i] != dst->kvm_features[i]) {
> virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> _("State of KVM feature '%s' differs: "
> @@ -28271,6 +28296,15 @@ virDomainDefFormatFeatures(virBufferPtr buf,
> def->kvm_features[j]));
> break;
>
> + case VIR_DOMAIN_KVM_DIRTY_RING:
> + if (def->kvm_features[j])
> + virBufferAsprintf(&childBuf, "<%s state='%s'
> size='%d'/>\n",
> + virDomainKVMTypeToString(j),
> + virTristateSwitchTypeToString(
> + def->kvm_features[j]),
> + def->dirty_gfn_count);
> + break;
> +
> /* coverity[dead_error_begin] */
> case VIR_DOMAIN_KVM_LAST:
> break;
> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
> index ec43bbe..120d490 100644
> --- a/src/conf/domain_conf.h
> +++ b/src/conf/domain_conf.h
> @@ -1917,6 +1917,7 @@ typedef enum {
> VIR_DOMAIN_KVM_HIDDEN = 0,
> VIR_DOMAIN_KVM_DEDICATED,
> VIR_DOMAIN_KVM_POLLCONTROL,
> + VIR_DOMAIN_KVM_DIRTY_RING,
>
> VIR_DOMAIN_KVM_LAST
> } virDomainKVM;
> @@ -2728,6 +2729,9 @@ struct _virDomainDef {
> callbacks failed for a non-critical reason
> (was not able to fill in some data) and thus
> should be re-run before starting */
> +
> + /* Number of dirty GFNs per ring */
> + unsigned int dirty_gfn_count;
> };
>
>
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index 0f660aa..31829ba 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -6525,6 +6525,9 @@ qemuBuildCpuCommandLine(virCommandPtr cmd,
> virBufferAddLit(&buf, ",kvm-poll-control=on");
> break;
>
> + case VIR_DOMAIN_KVM_DIRTY_RING:
> + break;
> +
> /* coverity[dead_error_begin] */
> case VIR_DOMAIN_KVM_LAST:
> break;
> @@ -6959,9 +6962,13 @@ qemuBuildAccelCommandLineTcgOptions(void)
>
>
> static void
> -qemuBuildAccelCommandLineKvmOptions(void)
> +qemuBuildAccelCommandLineKvmOptions(virBuffer *buf,
> + const virDomainDef *def)
> {
> - /* implemented in the next patch */
> + 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-gfn-count=%d",
> def->dirty_gfn_count);
> + }
> }
>
>
> @@ -6982,7 +6989,7 @@ qemuBuildAccelCommandLine(virCommandPtr cmd,
>
> case VIR_DOMAIN_VIRT_KVM:
> virBufferAddLit(&buf, "kvm");
> - qemuBuildAccelCommandLineKvmOptions();
> + qemuBuildAccelCommandLineKvmOptions(&buf, def);
> break;
>
> case VIR_DOMAIN_VIRT_KQEMU:
> --
> 1.8.3.1
>
>
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