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AJvYcCVkXnRKZQ//ZMjucoY77CCHVVQgM1MG9aUXQmm6n8MWxbhwo6q8nhXGNsZR5t1ay3MWEl7Wfcc/LjfbC293zws1ypsV X-Gm-Message-State: AOJu0Yzm0a/8BCYW3wMuyIBlmXXZxvv2QyFMQuDYU6WvU0qee5caNjnq +BhZQrdXUwczIUgU/p/YuJ7ZOVQs/KSojDLgwo2yiyiix6sB8gPro5g5VEC1P7FK3H2TVxGWLdF 1GLQIBsNdPGJkIumPsaT1buonsCY3vqd5iDVL X-Google-Smtp-Source: AGHT+IEdRz51c5N65alHGuS4aE+ios2xQWgcBA80yiRi8Tlzhh3yjCC+mkcAB9Nof7IUIQRUh/3WK8WOSXd71rI+7WI= X-Received: by 2002:aa7:c554:0:b0:56e:2b00:fcc7 with SMTP id s20-20020aa7c554000000b0056e2b00fcc7mr61633edr.0.1712873469805; Thu, 11 Apr 2024 15:11:09 -0700 (PDT) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20240126085444.324918-1-xiong.y.zhang@linux.intel.com> <20240126085444.324918-29-xiong.y.zhang@linux.intel.com> In-Reply-To: From: Jim Mattson Date: Thu, 11 Apr 2024 15:10:54 -0700 Message-ID: Subject: Re: [RFC PATCH 28/41] KVM: x86/pmu: Switch IA32_PERF_GLOBAL_CTRL at VM boundary To: Sean Christopherson Cc: Xiong Zhang , pbonzini@redhat.com, peterz@infradead.org, mizhang@google.com, kan.liang@intel.com, zhenyuw@linux.intel.com, dapeng1.mi@linux.intel.com, kvm@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, zhiyuan.lv@intel.com, eranian@google.com, irogers@google.com, samantha.alt@intel.com, like.xu.linux@gmail.com, chao.gao@intel.com, Xiong Zhang Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, Apr 11, 2024 at 2:54=E2=80=AFPM Sean Christopherson wrote: > > On Fri, Jan 26, 2024, Xiong Zhang wrote: > > +static void save_perf_global_ctrl_in_passthrough_pmu(struct vcpu_vmx *= vmx) > > +{ > > + struct kvm_pmu *pmu =3D vcpu_to_pmu(&vmx->vcpu); > > + int i; > > + > > + if (vm_exit_controls_get(vmx) & VM_EXIT_SAVE_IA32_PERF_GLOBAL_CTR= L) { > > + pmu->global_ctrl =3D vmcs_read64(GUEST_IA32_PERF_GLOBAL_C= TRL); > > + } else { > > + i =3D vmx_find_loadstore_msr_slot(&vmx->msr_autostore.gue= st, > > + MSR_CORE_PERF_GLOBAL_CTRL= ); > > + if (i < 0) > > + return; > > + pmu->global_ctrl =3D vmx->msr_autostore.guest.val[i].valu= e; > > As before, NAK to using the MSR load/store lists unless there's a *really= * good > reason I'm missing. The VM-exit control, "save IA32_PERF_GLOBAL_CTL," first appears in Sapphire Rapids. I think that's a compelling reason. > And we should consider adding VCPU_EXREG_GLOBAL_CTRL so that we can defer= the > VMREAD until KVM actually tries to access the guest value.