Messages in this thread | | | Subject | Re: [PATCH v3 02/16] KVM: x86: Register perf callbacks after calling vendor's hardware_setup() | From | Paolo Bonzini <> | Date | Wed, 22 Sep 2021 08:23:25 +0200 |
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On 22/09/21 02:05, Sean Christopherson wrote: > Wait to register perf callbacks until after doing vendor hardaware setup. > VMX's hardware_setup() configures Intel Processor Trace (PT) mode, and a > future fix to register the Intel PT guest interrupt hook if and only if > Intel PT is exposed to the guest will consume the configured PT mode. > > Delaying registration to hardware setup is effectively a nop as KVM's perf > hooks all pivot on the per-CPU current_vcpu, which is non-NULL only when > KVM is handling an IRQ/NMI in a VM-Exit path. I.e. current_vcpu will be > NULL throughout both kvm_arch_init() and kvm_arch_hardware_setup(). > > Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> > Cc: Artem Kashkanov <artem.kashkanov@intel.com> > Cc: stable@vger.kernel.org > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > arch/x86/kvm/x86.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 86539c1686fa..fb6015f97f9e 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -8426,8 +8426,6 @@ int kvm_arch_init(void *opaque) > > kvm_timer_init(); > > - perf_register_guest_info_callbacks(&kvm_guest_cbs); > - > if (boot_cpu_has(X86_FEATURE_XSAVE)) { > host_xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK); > supported_xcr0 = host_xcr0 & KVM_SUPPORTED_XCR0; > @@ -8461,7 +8459,6 @@ void kvm_arch_exit(void) > clear_hv_tscchange_cb(); > #endif > kvm_lapic_exit(); > - perf_unregister_guest_info_callbacks(&kvm_guest_cbs); > > if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) > cpufreq_unregister_notifier(&kvmclock_cpufreq_notifier_block, > @@ -11064,6 +11061,8 @@ int kvm_arch_hardware_setup(void *opaque) > memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops)); > kvm_ops_static_call_update(); > > + perf_register_guest_info_callbacks(&kvm_guest_cbs); > + > if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES)) > supported_xss = 0; > > @@ -11091,6 +11090,8 @@ int kvm_arch_hardware_setup(void *opaque) > > void kvm_arch_hardware_unsetup(void) > { > + perf_unregister_guest_info_callbacks(&kvm_guest_cbs); > + > static_call(kvm_x86_hardware_unsetup)(); > } > >
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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