From: Eduardo Habkost <ehabkost@redhat.com> To: qemu-devel@nongnu.org Cc: Marcelo Tosatti <mtosatti@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, kvm@vger.kernel.org, Haozhong Zhang <haozhong.zhang@intel.com> Subject: [PATCH v2 2/2] kvm: Allow invtsc migration if tsc-khz is set explicitly Date: Sun, 8 Jan 2017 15:13:30 -0200 [thread overview] Message-ID: <20170108171330.11129-3-ehabkost@redhat.com> (raw) In-Reply-To: <20170108171330.11129-1-ehabkost@redhat.com> We can safely allow a VM to be migrated with invtsc enabled if tsc-khz is set explicitly, because: * QEMU already refuses to start if it can't set the TSC frequency to the configured value. * Management software is already required to keep device configuration (including CPU configuration) the same on migration source and destination. Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> --- Changes v1 -> v2: * Reworded commit message --- target/i386/kvm.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/target/i386/kvm.c b/target/i386/kvm.c index a26290fdc1..6a51399945 100644 --- a/target/i386/kvm.c +++ b/target/i386/kvm.c @@ -962,15 +962,16 @@ int kvm_arch_init_vcpu(CPUState *cs) has_msr_mcg_ext_ctl = has_msr_feature_control = true; } - if ((env->features[FEAT_8000_0007_EDX] & CPUID_APM_INVTSC) && - invtsc_mig_blocker == NULL) { - /* for migration */ - error_setg(&invtsc_mig_blocker, - "State blocked by non-migratable CPU device" - " (invtsc flag)"); - migrate_add_blocker(invtsc_mig_blocker); - /* for savevm */ - vmstate_x86_cpu.unmigratable = 1; + if (!env->user_tsc_khz) { + if ((env->features[FEAT_8000_0007_EDX] & CPUID_APM_INVTSC) && + invtsc_mig_blocker == NULL) { + /* for migration */ + error_setg(&invtsc_mig_blocker, + "State blocked by non-migratable CPU device" + " (invtsc flag)"); + migrate_add_blocker(invtsc_mig_blocker); + /* for savevm */ + vmstate_x86_cpu.unmigratable = 1; } cpuid_data.cpuid.padding = 0; -- 2.11.0.259.g40922b1
WARNING: multiple messages have this Message-ID (diff)
From: Eduardo Habkost <ehabkost@redhat.com> To: qemu-devel@nongnu.org Cc: Marcelo Tosatti <mtosatti@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, kvm@vger.kernel.org, Haozhong Zhang <haozhong.zhang@intel.com> Subject: [Qemu-devel] [PATCH v2 2/2] kvm: Allow invtsc migration if tsc-khz is set explicitly Date: Sun, 8 Jan 2017 15:13:30 -0200 [thread overview] Message-ID: <20170108171330.11129-3-ehabkost@redhat.com> (raw) In-Reply-To: <20170108171330.11129-1-ehabkost@redhat.com> We can safely allow a VM to be migrated with invtsc enabled if tsc-khz is set explicitly, because: * QEMU already refuses to start if it can't set the TSC frequency to the configured value. * Management software is already required to keep device configuration (including CPU configuration) the same on migration source and destination. Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> --- Changes v1 -> v2: * Reworded commit message --- target/i386/kvm.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/target/i386/kvm.c b/target/i386/kvm.c index a26290fdc1..6a51399945 100644 --- a/target/i386/kvm.c +++ b/target/i386/kvm.c @@ -962,15 +962,16 @@ int kvm_arch_init_vcpu(CPUState *cs) has_msr_mcg_ext_ctl = has_msr_feature_control = true; } - if ((env->features[FEAT_8000_0007_EDX] & CPUID_APM_INVTSC) && - invtsc_mig_blocker == NULL) { - /* for migration */ - error_setg(&invtsc_mig_blocker, - "State blocked by non-migratable CPU device" - " (invtsc flag)"); - migrate_add_blocker(invtsc_mig_blocker); - /* for savevm */ - vmstate_x86_cpu.unmigratable = 1; + if (!env->user_tsc_khz) { + if ((env->features[FEAT_8000_0007_EDX] & CPUID_APM_INVTSC) && + invtsc_mig_blocker == NULL) { + /* for migration */ + error_setg(&invtsc_mig_blocker, + "State blocked by non-migratable CPU device" + " (invtsc flag)"); + migrate_add_blocker(invtsc_mig_blocker); + /* for savevm */ + vmstate_x86_cpu.unmigratable = 1; } cpuid_data.cpuid.padding = 0; -- 2.11.0.259.g40922b1
next prev parent reply other threads:[~2017-01-08 17:13 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-01-08 17:13 [PATCH v2 0/2] Allow migration with invtsc if TSC frequency is explicitly set Eduardo Habkost 2017-01-08 17:13 ` [Qemu-devel] " Eduardo Habkost 2017-01-08 17:13 ` [PATCH v2 1/2] kvm: Simplify invtsc check Eduardo Habkost 2017-01-08 17:13 ` [Qemu-devel] " Eduardo Habkost 2017-01-08 17:13 ` Eduardo Habkost [this message] 2017-01-08 17:13 ` [Qemu-devel] [PATCH v2 2/2] kvm: Allow invtsc migration if tsc-khz is set explicitly Eduardo Habkost 2017-01-08 17:19 ` [Qemu-devel] [PATCH v2 0/2] Allow migration with invtsc if TSC frequency is explicitly set no-reply 2017-01-08 17:28 ` Eduardo Habkost
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