January 2022 - Linux-stable-mirror

FAILED: patch "[PATCH] KVM: x86: don't print when fail to read/write pv eoi memory" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From ce5977b181c1613072eafbc7546bcb6c463ea68c Mon Sep 17 00:00:00 2001 From: Li RongQing <lirongqing(a)baidu.com> Date: Thu, 4 Nov 2021 19:56:13 +0800 Subject: [PATCH] KVM: x86: don't print when fail to read/write pv eoi memory If guest gives MSR_KVM_PV_EOI_EN a wrong value, this printk() will be trigged, and kernel log is spammed with the useless message Fixes: 0d88800d5472 ("kvm: x86: ioapic and apic debug macros cleanup") Reported-by: Vitaly Kuznetsov <vkuznets(a)redhat.com> Reviewed-by: Vitaly Kuznetsov <vkuznets(a)redhat.com> Signed-off-by: Li RongQing <lirongqing(a)baidu.com> Cc: stable(a)kernel.org Message-Id: <1636026974-50555-1-git-send-email-lirongqing(a)baidu.com> Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index bbac8477b3ec..8f4d872f3ffa 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -676,31 +676,25 @@ static inline bool pv_eoi_enabled(struct kvm_vcpu *vcpu) static bool pv_eoi_get_pending(struct kvm_vcpu *vcpu) { u8 val; - if (pv_eoi_get_user(vcpu, &val) < 0) { - printk(KERN_WARNING "Can't read EOI MSR value: 0x%llx\n", - (unsigned long long)vcpu->arch.pv_eoi.msr_val); + if (pv_eoi_get_user(vcpu, &val) < 0) return false; - } + return val & KVM_PV_EOI_ENABLED; } static void pv_eoi_set_pending(struct kvm_vcpu *vcpu) { - if (pv_eoi_put_user(vcpu, KVM_PV_EOI_ENABLED) < 0) { - printk(KERN_WARNING "Can't set EOI MSR value: 0x%llx\n", - (unsigned long long)vcpu->arch.pv_eoi.msr_val); + if (pv_eoi_put_user(vcpu, KVM_PV_EOI_ENABLED) < 0) return; - } + __set_bit(KVM_APIC_PV_EOI_PENDING, &vcpu->arch.apic_attention); } static void pv_eoi_clr_pending(struct kvm_vcpu *vcpu) { - if (pv_eoi_put_user(vcpu, KVM_PV_EOI_DISABLED) < 0) { - printk(KERN_WARNING "Can't clear EOI MSR value: 0x%llx\n", - (unsigned long long)vcpu->arch.pv_eoi.msr_val); + if (pv_eoi_put_user(vcpu, KVM_PV_EOI_DISABLED) < 0) return; - } + __clear_bit(KVM_APIC_PV_EOI_PENDING, &vcpu->arch.apic_attention); }

3 years

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FAILED: patch "[PATCH] KVM: x86: don't print when fail to read/write pv eoi memory" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From ce5977b181c1613072eafbc7546bcb6c463ea68c Mon Sep 17 00:00:00 2001 From: Li RongQing <lirongqing(a)baidu.com> Date: Thu, 4 Nov 2021 19:56:13 +0800 Subject: [PATCH] KVM: x86: don't print when fail to read/write pv eoi memory If guest gives MSR_KVM_PV_EOI_EN a wrong value, this printk() will be trigged, and kernel log is spammed with the useless message Fixes: 0d88800d5472 ("kvm: x86: ioapic and apic debug macros cleanup") Reported-by: Vitaly Kuznetsov <vkuznets(a)redhat.com> Reviewed-by: Vitaly Kuznetsov <vkuznets(a)redhat.com> Signed-off-by: Li RongQing <lirongqing(a)baidu.com> Cc: stable(a)kernel.org Message-Id: <1636026974-50555-1-git-send-email-lirongqing(a)baidu.com> Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index bbac8477b3ec..8f4d872f3ffa 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -676,31 +676,25 @@ static inline bool pv_eoi_enabled(struct kvm_vcpu *vcpu) static bool pv_eoi_get_pending(struct kvm_vcpu *vcpu) { u8 val; - if (pv_eoi_get_user(vcpu, &val) < 0) { - printk(KERN_WARNING "Can't read EOI MSR value: 0x%llx\n", - (unsigned long long)vcpu->arch.pv_eoi.msr_val); + if (pv_eoi_get_user(vcpu, &val) < 0) return false; - } + return val & KVM_PV_EOI_ENABLED; } static void pv_eoi_set_pending(struct kvm_vcpu *vcpu) { - if (pv_eoi_put_user(vcpu, KVM_PV_EOI_ENABLED) < 0) { - printk(KERN_WARNING "Can't set EOI MSR value: 0x%llx\n", - (unsigned long long)vcpu->arch.pv_eoi.msr_val); + if (pv_eoi_put_user(vcpu, KVM_PV_EOI_ENABLED) < 0) return; - } + __set_bit(KVM_APIC_PV_EOI_PENDING, &vcpu->arch.apic_attention); } static void pv_eoi_clr_pending(struct kvm_vcpu *vcpu) { - if (pv_eoi_put_user(vcpu, KVM_PV_EOI_DISABLED) < 0) { - printk(KERN_WARNING "Can't clear EOI MSR value: 0x%llx\n", - (unsigned long long)vcpu->arch.pv_eoi.msr_val); + if (pv_eoi_put_user(vcpu, KVM_PV_EOI_DISABLED) < 0) return; - } + __clear_bit(KVM_APIC_PV_EOI_PENDING, &vcpu->arch.apic_attention); }

3 years

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FAILED: patch "[PATCH] KVM: x86: Register Processor Trace interrupt hook iff PT" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From f4b027c5c8199abd4fb6f00d67d380548dbfdfa8 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 11 Nov 2021 02:07:24 +0000 Subject: [PATCH] KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest Override the Processor Trace (PT) interrupt handler for guest mode if and only if PT is configured for host+guest mode, i.e. is being used independently by both host and guest. If PT is configured for system mode, the host fully controls PT and must handle all events. Fixes: 8479e04e7d6b ("KVM: x86: Inject PMI for KVM guest") Reported-by: Alexander Shishkin <alexander.shishkin(a)linux.intel.com> Reported-by: Artem Kashkanov <artem.kashkanov(a)intel.com> Signed-off-by: Sean Christopherson <seanjc(a)google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Acked-by: Paolo Bonzini <pbonzini(a)redhat.com> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/20211111020738.2512932-4-seanjc@google.com diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index e5d8700319cc..41e858df5795 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1516,6 +1516,7 @@ struct kvm_x86_init_ops { int (*disabled_by_bios)(void); int (*check_processor_compatibility)(void); int (*hardware_setup)(void); + bool (*intel_pt_intr_in_guest)(void); struct kvm_x86_ops *runtime_ops; }; diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index ba66c171d951..7d90c8d443ac 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -7865,6 +7865,7 @@ static struct kvm_x86_init_ops vmx_init_ops __initdata = { .disabled_by_bios = vmx_disabled_by_bios, .check_processor_compatibility = vmx_check_processor_compat, .hardware_setup = hardware_setup, + .intel_pt_intr_in_guest = vmx_pt_mode_is_host_guest, .runtime_ops = &vmx_x86_ops, }; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 50f0cd16f2d4..760c4e3a8326 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8510,7 +8510,7 @@ static struct perf_guest_info_callbacks kvm_guest_cbs = { .is_in_guest = kvm_is_in_guest, .is_user_mode = kvm_is_user_mode, .get_guest_ip = kvm_get_guest_ip, - .handle_intel_pt_intr = kvm_handle_intel_pt_intr, + .handle_intel_pt_intr = NULL, }; #ifdef CONFIG_X86_64 @@ -11222,6 +11222,8 @@ int kvm_arch_hardware_setup(void *opaque) memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops)); kvm_ops_static_call_update(); + if (ops->intel_pt_intr_in_guest && ops->intel_pt_intr_in_guest()) + kvm_guest_cbs.handle_intel_pt_intr = kvm_handle_intel_pt_intr; perf_register_guest_info_callbacks(&kvm_guest_cbs); if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES)) @@ -11252,6 +11254,7 @@ int kvm_arch_hardware_setup(void *opaque) void kvm_arch_hardware_unsetup(void) { perf_unregister_guest_info_callbacks(&kvm_guest_cbs); + kvm_guest_cbs.handle_intel_pt_intr = NULL; static_call(kvm_x86_hardware_unsetup)(); }

3 years

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FAILED: patch "[PATCH] KVM: x86: Register perf callbacks after calling vendor's" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 5c7df80e2ce4c954c80eb4ecf5fa002a5ff5d2d6 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 11 Nov 2021 02:07:23 +0000 Subject: [PATCH] KVM: x86: Register perf callbacks after calling vendor's hardware_setup() 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(). Signed-off-by: Sean Christopherson <seanjc(a)google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Acked-by: Paolo Bonzini <pbonzini(a)redhat.com> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/20211111020738.2512932-3-seanjc@google.com diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index dc7eb5fddfd3..50f0cd16f2d4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8626,8 +8626,6 @@ 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; @@ -8659,7 +8657,6 @@ 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, @@ -11225,6 +11222,8 @@ 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; @@ -11252,6 +11251,8 @@ 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)(); }

3 years

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FAILED: patch "[PATCH] KVM: x86: Register perf callbacks after calling vendor's" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 5c7df80e2ce4c954c80eb4ecf5fa002a5ff5d2d6 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 11 Nov 2021 02:07:23 +0000 Subject: [PATCH] KVM: x86: Register perf callbacks after calling vendor's hardware_setup() 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(). Signed-off-by: Sean Christopherson <seanjc(a)google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Acked-by: Paolo Bonzini <pbonzini(a)redhat.com> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/20211111020738.2512932-3-seanjc@google.com diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index dc7eb5fddfd3..50f0cd16f2d4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8626,8 +8626,6 @@ 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; @@ -8659,7 +8657,6 @@ 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, @@ -11225,6 +11222,8 @@ 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; @@ -11252,6 +11251,8 @@ 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)(); }

3 years

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FAILED: patch "[PATCH] KVM: x86: Register perf callbacks after calling vendor's" failed to apply to 4.19-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 5c7df80e2ce4c954c80eb4ecf5fa002a5ff5d2d6 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 11 Nov 2021 02:07:23 +0000 Subject: [PATCH] KVM: x86: Register perf callbacks after calling vendor's hardware_setup() 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(). Signed-off-by: Sean Christopherson <seanjc(a)google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Acked-by: Paolo Bonzini <pbonzini(a)redhat.com> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/20211111020738.2512932-3-seanjc@google.com diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index dc7eb5fddfd3..50f0cd16f2d4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8626,8 +8626,6 @@ 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; @@ -8659,7 +8657,6 @@ 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, @@ -11225,6 +11222,8 @@ 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; @@ -11252,6 +11251,8 @@ 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)(); }

3 years

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FAILED: patch "[PATCH] KVM: x86: Register perf callbacks after calling vendor's" failed to apply to 4.9-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 5c7df80e2ce4c954c80eb4ecf5fa002a5ff5d2d6 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 11 Nov 2021 02:07:23 +0000 Subject: [PATCH] KVM: x86: Register perf callbacks after calling vendor's hardware_setup() 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(). Signed-off-by: Sean Christopherson <seanjc(a)google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Acked-by: Paolo Bonzini <pbonzini(a)redhat.com> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/20211111020738.2512932-3-seanjc@google.com diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index dc7eb5fddfd3..50f0cd16f2d4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8626,8 +8626,6 @@ 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; @@ -8659,7 +8657,6 @@ 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, @@ -11225,6 +11222,8 @@ 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; @@ -11252,6 +11251,8 @@ 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)(); }

3 years

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FAILED: patch "[PATCH] KVM: x86: Register perf callbacks after calling vendor's" failed to apply to 4.14-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 5c7df80e2ce4c954c80eb4ecf5fa002a5ff5d2d6 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 11 Nov 2021 02:07:23 +0000 Subject: [PATCH] KVM: x86: Register perf callbacks after calling vendor's hardware_setup() 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(). Signed-off-by: Sean Christopherson <seanjc(a)google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Acked-by: Paolo Bonzini <pbonzini(a)redhat.com> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/20211111020738.2512932-3-seanjc@google.com diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index dc7eb5fddfd3..50f0cd16f2d4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8626,8 +8626,6 @@ 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; @@ -8659,7 +8657,6 @@ 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, @@ -11225,6 +11222,8 @@ 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; @@ -11252,6 +11251,8 @@ 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)(); }

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FAILED: patch "[PATCH] KVM: x86: Register perf callbacks after calling vendor's" failed to apply to 4.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 5c7df80e2ce4c954c80eb4ecf5fa002a5ff5d2d6 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 11 Nov 2021 02:07:23 +0000 Subject: [PATCH] KVM: x86: Register perf callbacks after calling vendor's hardware_setup() 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(). Signed-off-by: Sean Christopherson <seanjc(a)google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Acked-by: Paolo Bonzini <pbonzini(a)redhat.com> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/20211111020738.2512932-3-seanjc@google.com diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index dc7eb5fddfd3..50f0cd16f2d4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8626,8 +8626,6 @@ 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; @@ -8659,7 +8657,6 @@ 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, @@ -11225,6 +11222,8 @@ 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; @@ -11252,6 +11251,8 @@ 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)(); }

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FAILED: patch "[PATCH] perf: Protect perf_guest_cbs with RCU" failed to apply to 4.19-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From ff083a2d972f56bebfd82409ca62e5dfce950961 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 11 Nov 2021 02:07:22 +0000 Subject: [PATCH] perf: Protect perf_guest_cbs with RCU Protect perf_guest_cbs with RCU to fix multiple possible errors. Luckily, all paths that read perf_guest_cbs already require RCU protection, e.g. to protect the callback chains, so only the direct perf_guest_cbs touchpoints need to be modified. Bug #1 is a simple lack of WRITE_ONCE/READ_ONCE behavior to ensure perf_guest_cbs isn't reloaded between a !NULL check and a dereference. Fixed via the READ_ONCE() in rcu_dereference(). Bug #2 is that on weakly-ordered architectures, updates to the callbacks themselves are not guaranteed to be visible before the pointer is made visible to readers. Fixed by the smp_store_release() in rcu_assign_pointer() when the new pointer is non-NULL. Bug #3 is that, because the callbacks are global, it's possible for readers to run in parallel with an unregisters, and thus a module implementing the callbacks can be unloaded while readers are in flight, resulting in a use-after-free. Fixed by a synchronize_rcu() call when unregistering callbacks. Bug #1 escaped notice because it's extremely unlikely a compiler will reload perf_guest_cbs in this sequence. perf_guest_cbs does get reloaded for future derefs, e.g. for ->is_user_mode(), but the ->is_in_guest() guard all but guarantees the consumer will win the race, e.g. to nullify perf_guest_cbs, KVM has to completely exit the guest and teardown down all VMs before KVM start its module unload / unregister sequence. This also makes it all but impossible to encounter bug #3. Bug #2 has not been a problem because all architectures that register callbacks are strongly ordered and/or have a static set of callbacks. But with help, unloading kvm_intel can trigger bug #1 e.g. wrapping perf_guest_cbs with READ_ONCE in perf_misc_flags() while spamming kvm_intel module load/unload leads to: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP CPU: 6 PID: 1825 Comm: stress Not tainted 5.14.0-rc2+ #459 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:perf_misc_flags+0x1c/0x70 Call Trace: perf_prepare_sample+0x53/0x6b0 perf_event_output_forward+0x67/0x160 __perf_event_overflow+0x52/0xf0 handle_pmi_common+0x207/0x300 intel_pmu_handle_irq+0xcf/0x410 perf_event_nmi_handler+0x28/0x50 nmi_handle+0xc7/0x260 default_do_nmi+0x6b/0x170 exc_nmi+0x103/0x130 asm_exc_nmi+0x76/0xbf Fixes: 39447b386c84 ("perf: Enhance perf to allow for guest statistic collection from host") Signed-off-by: Sean Christopherson <seanjc(a)google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Reviewed-by: Paolo Bonzini <pbonzini(a)redhat.com> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/20211111020738.2512932-2-seanjc@google.com diff --git a/arch/arm/kernel/perf_callchain.c b/arch/arm/kernel/perf_callchain.c index 3b69a76d341e..1626dfc6f6ce 100644 --- a/arch/arm/kernel/perf_callchain.c +++ b/arch/arm/kernel/perf_callchain.c @@ -62,9 +62,10 @@ user_backtrace(struct frame_tail __user *tail, void perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); struct frame_tail __user *tail; - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { + if (guest_cbs && guest_cbs->is_in_guest()) { /* We don't support guest os callchain now */ return; } @@ -98,9 +99,10 @@ callchain_trace(struct stackframe *fr, void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); struct stackframe fr; - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { + if (guest_cbs && guest_cbs->is_in_guest()) { /* We don't support guest os callchain now */ return; } @@ -111,18 +113,21 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re unsigned long perf_instruction_pointer(struct pt_regs *regs) { - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) - return perf_guest_cbs->get_guest_ip(); + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); + + if (guest_cbs && guest_cbs->is_in_guest()) + return guest_cbs->get_guest_ip(); return instruction_pointer(regs); } unsigned long perf_misc_flags(struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); int misc = 0; - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { - if (perf_guest_cbs->is_user_mode()) + if (guest_cbs && guest_cbs->is_in_guest()) { + if (guest_cbs->is_user_mode()) misc |= PERF_RECORD_MISC_GUEST_USER; else misc |= PERF_RECORD_MISC_GUEST_KERNEL; diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c index 4a72c2727309..86d9f2013172 100644 --- a/arch/arm64/kernel/perf_callchain.c +++ b/arch/arm64/kernel/perf_callchain.c @@ -102,7 +102,9 @@ compat_user_backtrace(struct compat_frame_tail __user *tail, void perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); + + if (guest_cbs && guest_cbs->is_in_guest()) { /* We don't support guest os callchain now */ return; } @@ -147,9 +149,10 @@ static bool callchain_trace(void *data, unsigned long pc) void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); struct stackframe frame; - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { + if (guest_cbs && guest_cbs->is_in_guest()) { /* We don't support guest os callchain now */ return; } @@ -160,18 +163,21 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, unsigned long perf_instruction_pointer(struct pt_regs *regs) { - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) - return perf_guest_cbs->get_guest_ip(); + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); + + if (guest_cbs && guest_cbs->is_in_guest()) + return guest_cbs->get_guest_ip(); return instruction_pointer(regs); } unsigned long perf_misc_flags(struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); int misc = 0; - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { - if (perf_guest_cbs->is_user_mode()) + if (guest_cbs && guest_cbs->is_in_guest()) { + if (guest_cbs->is_user_mode()) misc |= PERF_RECORD_MISC_GUEST_USER; else misc |= PERF_RECORD_MISC_GUEST_KERNEL; diff --git a/arch/csky/kernel/perf_callchain.c b/arch/csky/kernel/perf_callchain.c index ab55e98ee8f6..35318a635a5f 100644 --- a/arch/csky/kernel/perf_callchain.c +++ b/arch/csky/kernel/perf_callchain.c @@ -86,10 +86,11 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry, void perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); unsigned long fp = 0; /* C-SKY does not support virtualization. */ - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) + if (guest_cbs && guest_cbs->is_in_guest()) return; fp = regs->regs[4]; @@ -110,10 +111,11 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry, void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); struct stackframe fr; /* C-SKY does not support virtualization. */ - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { + if (guest_cbs && guest_cbs->is_in_guest()) { pr_warn("C-SKY does not support perf in guest mode!"); return; } diff --git a/arch/nds32/kernel/perf_event_cpu.c b/arch/nds32/kernel/perf_event_cpu.c index 0ce6f9f307e6..f38791960781 100644 --- a/arch/nds32/kernel/perf_event_cpu.c +++ b/arch/nds32/kernel/perf_event_cpu.c @@ -1363,6 +1363,7 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); unsigned long fp = 0; unsigned long gp = 0; unsigned long lp = 0; @@ -1371,7 +1372,7 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, leaf_fp = 0; - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { + if (guest_cbs && guest_cbs->is_in_guest()) { /* We don't support guest os callchain now */ return; } @@ -1479,9 +1480,10 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); struct stackframe fr; - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { + if (guest_cbs && guest_cbs->is_in_guest()) { /* We don't support guest os callchain now */ return; } @@ -1493,20 +1495,23 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, unsigned long perf_instruction_pointer(struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); + /* However, NDS32 does not support virtualization */ - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) - return perf_guest_cbs->get_guest_ip(); + if (guest_cbs && guest_cbs->is_in_guest()) + return guest_cbs->get_guest_ip(); return instruction_pointer(regs); } unsigned long perf_misc_flags(struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); int misc = 0; /* However, NDS32 does not support virtualization */ - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { - if (perf_guest_cbs->is_user_mode()) + if (guest_cbs && guest_cbs->is_in_guest()) { + if (guest_cbs->is_user_mode()) misc |= PERF_RECORD_MISC_GUEST_USER; else misc |= PERF_RECORD_MISC_GUEST_KERNEL; diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c index 0bb1854dce83..8ecfc4c128bc 100644 --- a/arch/riscv/kernel/perf_callchain.c +++ b/arch/riscv/kernel/perf_callchain.c @@ -56,10 +56,11 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry, void perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); unsigned long fp = 0; /* RISC-V does not support perf in guest mode. */ - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) + if (guest_cbs && guest_cbs->is_in_guest()) return; fp = regs->s0; @@ -78,8 +79,10 @@ static bool fill_callchain(void *entry, unsigned long pc) void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); + /* RISC-V does not support perf in guest mode. */ - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { + if (guest_cbs && guest_cbs->is_in_guest()) { pr_warn("RISC-V does not support perf in guest mode!"); return; } diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 38b2c779146f..32cec290d3ad 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2768,10 +2768,11 @@ static bool perf_hw_regs(struct pt_regs *regs) void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); struct unwind_state state; unsigned long addr; - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { + if (guest_cbs && guest_cbs->is_in_guest()) { /* TODO: We don't support guest os callchain now */ return; } @@ -2871,10 +2872,11 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent void perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); struct stack_frame frame; const struct stack_frame __user *fp; - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { + if (guest_cbs && guest_cbs->is_in_guest()) { /* TODO: We don't support guest os callchain now */ return; } @@ -2951,18 +2953,21 @@ static unsigned long code_segment_base(struct pt_regs *regs) unsigned long perf_instruction_pointer(struct pt_regs *regs) { - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) - return perf_guest_cbs->get_guest_ip(); + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); + + if (guest_cbs && guest_cbs->is_in_guest()) + return guest_cbs->get_guest_ip(); return regs->ip + code_segment_base(regs); } unsigned long perf_misc_flags(struct pt_regs *regs) { + struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); int misc = 0; - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { - if (perf_guest_cbs->is_user_mode()) + if (guest_cbs && guest_cbs->is_in_guest()) { + if (guest_cbs->is_user_mode()) misc |= PERF_RECORD_MISC_GUEST_USER; else misc |= PERF_RECORD_MISC_GUEST_KERNEL; diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index 42cf01ecdd13..2258e02ca350 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -2837,6 +2837,7 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status) { struct perf_sample_data data; struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); + struct perf_guest_info_callbacks *guest_cbs; int bit; int handled = 0; u64 intel_ctrl = hybrid(cpuc->pmu, intel_ctrl); @@ -2903,9 +2904,11 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status) */ if (__test_and_clear_bit(GLOBAL_STATUS_TRACE_TOPAPMI_BIT, (unsigned long *)&status)) { handled++; - if (unlikely(perf_guest_cbs && perf_guest_cbs->is_in_guest() && - perf_guest_cbs->handle_intel_pt_intr)) - perf_guest_cbs->handle_intel_pt_intr(); + + guest_cbs = perf_get_guest_cbs(); + if (unlikely(guest_cbs && guest_cbs->is_in_guest() && + guest_cbs->handle_intel_pt_intr)) + guest_cbs->handle_intel_pt_intr(); else intel_pt_interrupt(); } diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 0dcfd265beed..318c489b735b 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1240,7 +1240,18 @@ extern void perf_event_bpf_event(struct bpf_prog *prog, enum perf_bpf_event_type type, u16 flags); -extern struct perf_guest_info_callbacks *perf_guest_cbs; +extern struct perf_guest_info_callbacks __rcu *perf_guest_cbs; +static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void) +{ + /* + * Callbacks are RCU-protected and must be READ_ONCE to avoid reloading + * the callbacks between a !NULL check and dereferences, to ensure + * pending stores/changes to the callback pointers are visible before a + * non-NULL perf_guest_cbs is visible to readers, and to prevent a + * module from unloading callbacks while readers are active. + */ + return rcu_dereference(perf_guest_cbs); +} extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks); extern int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks); diff --git a/kernel/events/core.c b/kernel/events/core.c index 523106a506ee..c552e1bfcaea 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6526,18 +6526,25 @@ static void perf_pending_event(struct irq_work *entry) * Later on, we might change it to a list if there is * another virtualization implementation supporting the callbacks. */ -struct perf_guest_info_callbacks *perf_guest_cbs; +struct perf_guest_info_callbacks __rcu *perf_guest_cbs; int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs) { - perf_guest_cbs = cbs; + if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs))) + return -EBUSY; + + rcu_assign_pointer(perf_guest_cbs, cbs); return 0; } EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks); int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs) { - perf_guest_cbs = NULL; + if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs) != cbs)) + return -EINVAL; + + rcu_assign_pointer(perf_guest_cbs, NULL); + synchronize_rcu(); return 0; } EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);

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