From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60838) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cQH2K-0004BV-Nj for qemu-devel@nongnu.org; Sun, 08 Jan 2017 12:13:41 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cQH2J-0006Hr-Im for qemu-devel@nongnu.org; Sun, 08 Jan 2017 12:13:40 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42092) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cQH2J-0006Gt-DS for qemu-devel@nongnu.org; Sun, 08 Jan 2017 12:13:39 -0500 From: Eduardo Habkost Date: Sun, 8 Jan 2017 15:13:30 -0200 Message-Id: <20170108171330.11129-3-ehabkost@redhat.com> In-Reply-To: <20170108171330.11129-1-ehabkost@redhat.com> References: <20170108171330.11129-1-ehabkost@redhat.com> Subject: [Qemu-devel] [PATCH v2 2/2] kvm: Allow invtsc migration if tsc-khz is set explicitly List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Marcelo Tosatti , Paolo Bonzini , kvm@vger.kernel.org, Haozhong Zhang 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 --- 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