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Mon, 31 Mar 2025 01:34:50 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=cc :content-transfer-encoding:date:from:in-reply-to:message-id :mime-version:references:subject:to; s=corp-2023-11-20; bh=QEmFv iGAK3HVPMhByP1bT/49mKbRwqTnouSzcbyuEfk=; b=jzNav93CoUSl4bywu8s5E IdArw9Qr9mdgDLQiXyg8h7WzMuReKqSewNeH6DrNzl3xGXAeG6Zk2E1PHgdgzIoQ O9ggBt3+G/yP54RpWhZGTadVFsANvUWEp0LffwiAEplo/IIh6T76c3CqcAvEI2rB 0Ag2hrFzh/cJYdkatwEfO1KvMRER7jMbQBuo16n2yz7QSZTIkEY5lDql2CgBckhD h6Ym9rqB1lLQIm2a0P641rSADUtKLo6loUjnSRDBGxy0ljaYOILsmu/2tbYV95w+ 0fFwNc7X41JfjH60NVxIl9x+1T4OEqQDy+1t6PBm1ByfWL3X1PFz39xnP4SjOILa A== From: Dongli Zhang To: qemu-devel@nongnu.org, kvm@vger.kernel.org, qemu-arm@nongnu.org, qemu-ppc@nongnu.org, qemu-riscv@nongnu.org, qemu-s390x@nongnu.org Cc: pbonzini@redhat.com, zhao1.liu@intel.com, mtosatti@redhat.com, sandipan.das@amd.com, babu.moger@amd.com, likexu@tencent.com, like.xu.linux@gmail.com, groug@kaod.org, khorenko@virtuozzo.com, alexander.ivanov@virtuozzo.com, den@virtuozzo.com, davydov-max@yandex-team.ru, xiaoyao.li@intel.com, dapeng1.mi@linux.intel.com, joe.jin@oracle.com, peter.maydell@linaro.org, gaosong@loongson.cn, chenhuacai@kernel.org, philmd@linaro.org, aurelien@aurel32.net, jiaxun.yang@flygoat.com, arikalo@gmail.com, npiggin@gmail.com, danielhb413@gmail.com, palmer@dabbelt.com, alistair.francis@wdc.com, liwei1518@gmail.com, zhiwei_liu@linux.alibaba.com, pasic@linux.ibm.com, borntraeger@linux.ibm.com, richard.henderson@linaro.org, david@redhat.com, iii@linux.ibm.com, thuth@redhat.com, flavra@baylibre.com, ewanhai-oc@zhaoxin.com, ewanhai@zhaoxin.com, cobechen@zhaoxin.com, louisqi@zhaoxin.com, liamni@zhaoxin.com, frankzhu@zhaoxin.com, silviazhao@zhaoxin.com Subject: [PATCH v3 04/10] target/i386/kvm: set KVM_PMU_CAP_DISABLE if "-pmu" is configured Date: Sun, 30 Mar 2025 18:32:23 -0700 Message-ID: <20250331013307.11937-5-dongli.zhang@oracle.com> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20250331013307.11937-1-dongli.zhang@oracle.com> References: <20250331013307.11937-1-dongli.zhang@oracle.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1095,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-03-30_11,2025-03-27_02,2024-11-22_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 phishscore=0 suspectscore=0 mlxscore=0 malwarescore=0 spamscore=0 bulkscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2502280000 definitions=main-2503310009 X-Proofpoint-GUID: 1utXdqAG6eZnea9mOCSXfz-YhYY6YzKV X-Proofpoint-ORIG-GUID: 1utXdqAG6eZnea9mOCSXfz-YhYY6YzKV 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=205.220.177.32; envelope-from=dongli.zhang@oracle.com; helo=mx0b-00069f02.pphosted.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_MED=-0.368, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H5=-1, RCVD_IN_MSPIKE_WL=-0.01, 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: 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 @oracle.com) X-ZM-MESSAGEID: 1743385166541019100 Content-Type: text/plain; charset="utf-8" Although AMD PERFCORE and PerfMonV2 are removed when "-pmu" is configured, there is no way to fully disable KVM AMD PMU virtualization. Neither "-cpu host,-pmu" nor "-cpu EPYC" achieves this. As a result, the following message still appears in the VM dmesg: [ 0.263615] Performance Events: AMD PMU driver. However, the expected output should be: [ 0.596381] Performance Events: PMU not available due to virtualization,= using software events only. [ 0.600972] NMI watchdog: Perf NMI watchdog permanently disabled This occurs because AMD does not use any CPUID bit to indicate PMU availability. To address this, KVM_CAP_PMU_CAPABILITY is used to set KVM_PMU_CAP_DISABLE when "-pmu" is configured. Signed-off-by: Dongli Zhang Reviewed-by: Xiaoyao Li Reviewed-by: Zhao Liu --- Changed since v1: - Switch back to the initial implementation with "-pmu". https://lore.kernel.org/all/20221119122901.2469-3-dongli.zhang@oracle.com - Mention that "KVM_PMU_CAP_DISABLE doesn't change the PMU behavior on Intel platform because current "pmu" property works as expected." Changed since v2: - Change has_pmu_cap to pmu_cap. - Use (pmu_cap & KVM_PMU_CAP_DISABLE) instead of only pmu_cap in if statement. - Add Reviewed-by from Xiaoyao and Zhao as the change is minor. target/i386/kvm/kvm.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index f41e190fb8..579c0f7e0b 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -176,6 +176,8 @@ static int has_triple_fault_event; =20 static bool has_msr_mcg_ext_ctl; =20 +static int pmu_cap; + static struct kvm_cpuid2 *cpuid_cache; static struct kvm_cpuid2 *hv_cpuid_cache; static struct kvm_msr_list *kvm_feature_msrs; @@ -2053,6 +2055,33 @@ full: =20 int kvm_arch_pre_create_vcpu(CPUState *cpu, Error **errp) { + static bool first =3D true; + int ret; + + if (first) { + first =3D false; + + /* + * Since Linux v5.18, KVM provides a VM-level capability to easily + * disable PMUs; however, QEMU has been providing PMU property per + * CPU since v1.6. In order to accommodate both, have to configure + * the VM-level capability here. + * + * KVM_PMU_CAP_DISABLE doesn't change the PMU + * behavior on Intel platform because current "pmu" property works + * as expected. + */ + if ((pmu_cap & KVM_PMU_CAP_DISABLE) && !X86_CPU(cpu)->enable_pmu) { + ret =3D kvm_vm_enable_cap(kvm_state, KVM_CAP_PMU_CAPABILITY, 0, + KVM_PMU_CAP_DISABLE); + if (ret < 0) { + error_setg_errno(errp, -ret, + "Failed to set KVM_PMU_CAP_DISABLE"); + return ret; + } + } + } + return 0; } =20 @@ -3351,6 +3380,8 @@ int kvm_arch_init(MachineState *ms, KVMState *s) } } =20 + pmu_cap =3D kvm_check_extension(s, KVM_CAP_PMU_CAPABILITY); + return 0; } =20 --=20 2.39.3