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a="73462314" X-IronPort-AV: E=Sophos;i="6.21,258,1763452800"; d="scan'208";a="73462314" X-CSE-ConnectionGUID: 2FkKWPuER+ml+TpE6QAjEg== X-CSE-MsgGUID: HdmXgQTDRBeyAmnBuEbHGA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,258,1763452800"; d="scan'208";a="208001763" From: Zide Chen To: qemu-devel@nongnu.org, kvm@vger.kernel.org, Paolo Bonzini , Zhao Liu , Peter Xu , Fabiano Rosas Cc: Xiaoyao Li , Dongli Zhang , Dapeng Mi , Zide Chen Subject: [PATCH V2 02/11] target/i386: Don't save/restore PERF_GLOBAL_OVF_CTRL MSR Date: Wed, 28 Jan 2026 15:09:39 -0800 Message-ID: <20260128231003.268981-3-zide.chen@intel.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260128231003.268981-1-zide.chen@intel.com> References: <20260128231003.268981-1-zide.chen@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=192.198.163.13; envelope-from=zide.chen@intel.com; helo=mgamail.intel.com X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @intel.com) X-ZM-MESSAGEID: 1769642359030158500 Content-Type: text/plain; charset="utf-8" From: Dapeng Mi MSR_CORE_PERF_GLOBAL_OVF_CTRL is a write-only MSR and reads always return zero. Saving and restoring this MSR is therefore unnecessary. Replace VMSTATE_UINT64 with VMSTATE_UNUSED in the VMStateDescription to ignore env.msr_global_ovf_ctrl during migration. This avoids the need to bump version_id and does not introduce any migration incompatibility. Signed-off-by: Dapeng Mi Signed-off-by: Zide Chen --- V2: - No changes. target/i386/cpu.h | 1 - target/i386/kvm/kvm.c | 6 ------ target/i386/machine.c | 4 ++-- 3 files changed, 2 insertions(+), 9 deletions(-) diff --git a/target/i386/cpu.h b/target/i386/cpu.h index f02812bfd19f..f6e9b274e2ff 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -2086,7 +2086,6 @@ typedef struct CPUArchState { uint64_t msr_fixed_ctr_ctrl; uint64_t msr_global_ctrl; uint64_t msr_global_status; - uint64_t msr_global_ovf_ctrl; uint64_t msr_fixed_counters[MAX_FIXED_COUNTERS]; uint64_t msr_gp_counters[MAX_GP_COUNTERS]; uint64_t msr_gp_evtsel[MAX_GP_COUNTERS]; diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index 7b9b740a8e5a..cffbc90d1c50 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -4069,8 +4069,6 @@ static int kvm_put_msrs(X86CPU *cpu, KvmPutState leve= l) if (has_architectural_pmu_version > 1) { kvm_msr_entry_add(cpu, MSR_CORE_PERF_GLOBAL_STATUS, env->msr_global_status); - kvm_msr_entry_add(cpu, MSR_CORE_PERF_GLOBAL_OVF_CTRL, - env->msr_global_ovf_ctrl); =20 /* Now start the PMU. */ kvm_msr_entry_add(cpu, MSR_CORE_PERF_FIXED_CTR_CTRL, @@ -4588,7 +4586,6 @@ static int kvm_get_msrs(X86CPU *cpu) kvm_msr_entry_add(cpu, MSR_CORE_PERF_FIXED_CTR_CTRL, 0); kvm_msr_entry_add(cpu, MSR_CORE_PERF_GLOBAL_CTRL, 0); kvm_msr_entry_add(cpu, MSR_CORE_PERF_GLOBAL_STATUS, 0); - kvm_msr_entry_add(cpu, MSR_CORE_PERF_GLOBAL_OVF_CTRL, 0); } for (i =3D 0; i < num_architectural_pmu_fixed_counters; i++) { kvm_msr_entry_add(cpu, MSR_CORE_PERF_FIXED_CTR0 + i, 0); @@ -4917,9 +4914,6 @@ static int kvm_get_msrs(X86CPU *cpu) case MSR_CORE_PERF_GLOBAL_STATUS: env->msr_global_status =3D msrs[i].data; break; - case MSR_CORE_PERF_GLOBAL_OVF_CTRL: - env->msr_global_ovf_ctrl =3D msrs[i].data; - break; case MSR_CORE_PERF_FIXED_CTR0 ... MSR_CORE_PERF_FIXED_CTR0 + MAX_F= IXED_COUNTERS - 1: env->msr_fixed_counters[index - MSR_CORE_PERF_FIXED_CTR0] =3D = msrs[i].data; break; diff --git a/target/i386/machine.c b/target/i386/machine.c index c9139612813b..1125c8a64ec5 100644 --- a/target/i386/machine.c +++ b/target/i386/machine.c @@ -666,7 +666,7 @@ static bool pmu_enable_needed(void *opaque) int i; =20 if (env->msr_fixed_ctr_ctrl || env->msr_global_ctrl || - env->msr_global_status || env->msr_global_ovf_ctrl) { + env->msr_global_status) { return true; } for (i =3D 0; i < MAX_FIXED_COUNTERS; i++) { @@ -692,7 +692,7 @@ static const VMStateDescription vmstate_msr_architectur= al_pmu =3D { VMSTATE_UINT64(env.msr_fixed_ctr_ctrl, X86CPU), VMSTATE_UINT64(env.msr_global_ctrl, X86CPU), VMSTATE_UINT64(env.msr_global_status, X86CPU), - VMSTATE_UINT64(env.msr_global_ovf_ctrl, X86CPU), + VMSTATE_UNUSED(sizeof(uint64_t)), VMSTATE_UINT64_ARRAY(env.msr_fixed_counters, X86CPU, MAX_FIXED_COU= NTERS), VMSTATE_UINT64_ARRAY(env.msr_gp_counters, X86CPU, MAX_GP_COUNTERS), VMSTATE_UINT64_ARRAY(env.msr_gp_evtsel, X86CPU, MAX_GP_COUNTERS), --=20 2.52.0