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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id f207sm8747292wme.9.2020.02.05.06.31.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Feb 2020 06:31:52 -0800 (PST) From: Vitaly Kuznetsov To: Sean Christopherson , Paolo Bonzini Cc: Sean Christopherson , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 03/26] KVM: x86: Snapshot MSR index in a local variable when processing lists In-Reply-To: <20200129234640.8147-4-sean.j.christopherson@intel.com> References: <20200129234640.8147-1-sean.j.christopherson@intel.com> <20200129234640.8147-4-sean.j.christopherson@intel.com> Date: Wed, 05 Feb 2020 15:31:51 +0100 Message-ID: <87h805ksvc.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Sean Christopherson writes: > Snapshot the MSR index when processing the virtualized and emulated MSR > lists in kvm_init_msr_list() to improve code readability, particularly > in the RTIT and PerfMon MSR checks. > > No functional change intended. > > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/x86.c | 22 +++++++++++++--------- > 1 file changed, 13 insertions(+), 9 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 24597526b5de..3d4a5326d84e 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -5214,7 +5214,7 @@ long kvm_arch_vm_ioctl(struct file *filp, > static void kvm_init_msr_list(void) > { > struct x86_pmu_capability x86_pmu; > - u32 dummy[2]; > + u32 dummy[2], msr_index; > unsigned i; > > BUILD_BUG_ON_MSG(INTEL_PMC_MAX_FIXED != 4, > @@ -5227,14 +5227,16 @@ static void kvm_init_msr_list(void) > num_msr_based_features = 0; > > for (i = 0; i < ARRAY_SIZE(msrs_to_save_all); i++) { > - if (rdmsr_safe(msrs_to_save_all[i], &dummy[0], &dummy[1]) < 0) > + msr_index = msrs_to_save_all[i]; > + > + if (rdmsr_safe(msr_index, &dummy[0], &dummy[1]) < 0) > continue; > > /* > * Even MSRs that are valid in the host may not be exposed > * to the guests in some cases. > */ > - switch (msrs_to_save_all[i]) { > + switch (msr_index) { > case MSR_IA32_BNDCFGS: > if (!kvm_mpx_supported()) > continue; > @@ -5262,17 +5264,17 @@ static void kvm_init_msr_list(void) > break; > case MSR_IA32_RTIT_ADDR0_A ... MSR_IA32_RTIT_ADDR3_B: > if (!kvm_x86_ops->pt_supported() || > - msrs_to_save_all[i] - MSR_IA32_RTIT_ADDR0_A >= > + msr_index - MSR_IA32_RTIT_ADDR0_A >= > intel_pt_validate_hw_cap(PT_CAP_num_address_ranges) * 2) > continue; > break; > case MSR_ARCH_PERFMON_PERFCTR0 ... MSR_ARCH_PERFMON_PERFCTR0 + 17: > - if (msrs_to_save_all[i] - MSR_ARCH_PERFMON_PERFCTR0 >= > + if (msr_index - MSR_ARCH_PERFMON_PERFCTR0 >= > min(INTEL_PMC_MAX_GENERIC, x86_pmu.num_counters_gp)) > continue; > break; > case MSR_ARCH_PERFMON_EVENTSEL0 ... MSR_ARCH_PERFMON_EVENTSEL0 + 17: > - if (msrs_to_save_all[i] - MSR_ARCH_PERFMON_EVENTSEL0 >= > + if (msr_index - MSR_ARCH_PERFMON_EVENTSEL0 >= > min(INTEL_PMC_MAX_GENERIC, x86_pmu.num_counters_gp)) > continue; > break; > @@ -5280,14 +5282,16 @@ static void kvm_init_msr_list(void) > break; > } > > - msrs_to_save[num_msrs_to_save++] = msrs_to_save_all[i]; > + msrs_to_save[num_msrs_to_save++] = msr_index; > } > > for (i = 0; i < ARRAY_SIZE(emulated_msrs_all); i++) { > - if (!kvm_x86_ops->has_emulated_msr(emulated_msrs_all[i])) > + msr_index = emulated_msrs_all[i]; > + > + if (!kvm_x86_ops->has_emulated_msr(msr_index)) > continue; > > - emulated_msrs[num_emulated_msrs++] = emulated_msrs_all[i]; > + emulated_msrs[num_emulated_msrs++] = msr_index; > } > > for (i = 0; i < ARRAY_SIZE(msr_based_features_all); i++) { Reviewed-by: Vitaly Kuznetsov -- Vitaly