When guest CPU PM is enabled, and with -cpu host, expose the host CPU MWAIT leaf to guest so guest can make good PM decisions.
Signed-off-by: Michael S. Tsirkin <m...@redhat.com> --- This builds but is untested. Is this a reasonable way to go about it? target/i386/cpu.h | 9 +++++++++ target/i386/cpu.c | 18 +++++++++++++----- 2 files changed, 22 insertions(+), 5 deletions(-) diff --git a/target/i386/cpu.h b/target/i386/cpu.h index 664504610e..309f804573 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -1378,6 +1378,15 @@ struct X86CPU { /* if true the CPUID code directly forward host cache leaves to the guest */ bool cache_info_passthrough; + /* if true the CPUID code directly forwards + * host monitor/mwait leaves to the guest */ + struct { + uint32_t eax; + uint32_t ebx; + uint32_t ecx; + uint32_t edx; + } mwait; + /* Features that were filtered out because of missing host capabilities */ uint32_t filtered_features[FEATURE_WORDS]; diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 94260412e2..a49443de56 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -3760,11 +3760,11 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count, } break; case 5: - /* mwait info: needed for Core compatibility */ - *eax = 0; /* Smallest monitor-line size in bytes */ - *ebx = 0; /* Largest monitor-line size in bytes */ - *ecx = CPUID_MWAIT_EMX | CPUID_MWAIT_IBE; - *edx = 0; + /* MONITOR/MWAIT Leaf */ + *eax = cpu->mwait.eax; /* Smallest monitor-line size in bytes */ + *ebx = cpu->mwait.ebx; /* Largest monitor-line size in bytes */ + *ecx = cpu->mwait.ecx; /* flags */ + *edx = cpu->mwait.edx; /* mwait substates */ break; case 6: /* Thermal and Power Leaf */ @@ -4595,6 +4595,14 @@ static void x86_cpu_realizefn(DeviceState *dev, Error **errp) goto out; } + if (xcc->host_cpuid_required && enable_cpu_pm) { + host_cpuid(5, 0, &cpu->mwait.eax, &cpu->mwait.ebx, + &cpu->mwait.ecx, &cpu->mwait.edx); + } + /* We always wake on interrupt even if host does not have the capability */ + /* mwait extended info: needed for Core compatibility */ + cpu->mwait.ecx |= CPUID_MWAIT_EMX | CPUID_MWAIT_IBE; + if (cpu->apic_id == UNASSIGNED_APIC_ID) { error_setg(errp, "apic-id property was not initialized properly"); return; -- MST