Re: [libvirt] [PATCH v3 2/3] PowerPC : Add support for launching VMs in 'compat' mode.

>From c3572e59f1e56322ba92ab35e31da48dd63b7cec Mon Sep 17 00:00:00 2001 From: Prerna Saxena <prerna(a)linux.vnet.ibm.com&gt; Date: Tue, 21 Oct 2014 01:06:51 -0400 PowerISA allows processors to run VMs in binary compatibility ("compat") mode supporting an older version of ISA. QEMU has recently added support to explicitly denote a VM running in compatibility mode through commit 6d9412ea & 8dfa3a5e85. Now, a "compat" mode VM can be run by invoking this qemu commandline on a POWER8 host: -cpu host,compat=power7. This patch allows libvirt to extend the "fallback" semantics of cpu model to describe this new mode for PowerKVM guests. As an example: When a user wants to request a power7 vm to run in compatibility mode on a Power8 host, this can be described in XML as follows : <cpu mode='host-model'> <model fallback='compat'>power7</model> </cpu> Signed-off-by: Prerna Saxena <prerna(a)linux.vnet.ibm.com&gt; Signed-off-by: Li Zhang <zhlcindy(a)linux.vnet.ibm.com&gt; Signed-off-by: Pradipta Kr. Banerjee <bpradip(a)in.ibm.com&gt; --- docs/schemas/domaincommon.rng | 1 + src/conf/cpu_conf.c | 4 +++- src/conf/cpu_conf.h | 1 + src/cpu/cpu_powerpc.c | 14 ++++---------- src/qemu/qemu_command.c | 11 ++++++++++- 5 files changed, 19 insertions(+), 12 deletions(-) diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng index 20d81ae..ebab482 100644 --- a/docs/schemas/domaincommon.rng +++ b/docs/schemas/domaincommon.rng @@ -4067,6 +4067,7 @@ <choice> <value>allow</value> <value>forbid</value> + <value>compat</value> </choice> </attribute> </optional>

diff --git a/src/conf/cpu_conf.c b/src/conf/cpu_conf.c index 9b7fbb0..e12d3db 100644 --- a/src/conf/cpu_conf.c +++ b/src/conf/cpu_conf.c @@ -47,7 +47,8 @@ VIR_ENUM_IMPL(virCPUMatch, VIR_CPU_MATCH_LAST, VIR_ENUM_IMPL(virCPUFallback, VIR_CPU_FALLBACK_LAST, "allow", - "forbid") + "forbid", + "compat") VIR_ENUM_IMPL(virCPUFeaturePolicy, VIR_CPU_FEATURE_LAST, "force", @@ -619,6 +620,7 @@ virCPUDefFormatBuf(virBufferPtr buf, return 0; formatModel = (def->mode == VIR_CPU_MODE_CUSTOM || + def->mode == VIR_CPU_MODE_HOST_MODEL || (flags & VIR_DOMAIN_XML_UPDATE_CPU)); formatFallback = (def->type == VIR_CPU_TYPE_GUEST && (def->mode == VIR_CPU_MODE_HOST_MODEL || diff --git a/src/conf/cpu_conf.h b/src/conf/cpu_conf.h index d45210b..69d8584 100644 --- a/src/conf/cpu_conf.h +++ b/src/conf/cpu_conf.h @@ -65,6 +65,7 @@ VIR_ENUM_DECL(virCPUMatch) typedef enum { VIR_CPU_FALLBACK_ALLOW, VIR_CPU_FALLBACK_FORBID, + VIR_CPU_FALLBACK_COMPAT, VIR_CPU_FALLBACK_LAST } virCPUFallback; diff --git a/src/cpu/cpu_powerpc.c b/src/cpu/cpu_powerpc.c index d591c18..ad887fe 100644 --- a/src/cpu/cpu_powerpc.c +++ b/src/cpu/cpu_powerpc.c @@ -479,7 +479,8 @@ ppcDecode(virCPUDefPtr cpu, goto cleanup; } - if (!cpuModelIsAllowed(model->name, models, nmodels)) { + if (cpu->fallback != VIR_CPU_FALLBACK_COMPAT && + !cpuModelIsAllowed(model->name, models, nmodels)) {

virReportError(VIR_ERR_CONFIG_UNSUPPORTED, _("CPU model %s is not supported by hypervisor"), model->name); @@ -562,8 +563,8 @@ ppcUpdate(virCPUDefPtr guest, static virCPUDefPtr ppcBaseline(virCPUDefPtr *cpus, unsigned int ncpus, - const char **models, - unsigned int nmodels, + const char **models ATTRIBUTE_UNUSED, + unsigned int nmodels ATTRIBUTE_UNUSED, unsigned int flags) {