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Sat, 15 Apr 2023 09:41:01 -0700 (PDT) Date: Sat, 15 Apr 2023 09:40:29 -0700 In-Reply-To: <20230415164029.526895-1-reijiw@google.com> Mime-Version: 1.0 References: <20230415164029.526895-1-reijiw@google.com> X-Mailer: git-send-email 2.40.0.634.g4ca3ef3211-goog Message-ID: <20230415164029.526895-3-reijiw@google.com> Subject: [PATCH v3 2/2] KVM: arm64: PMU: Don't overwrite PMUSERENR with vcpu loaded From: Reiji Watanabe To: Marc Zyngier , Mark Rutland , Oliver Upton , Will Deacon , Catalin Marinas , kvmarm@lists.linux.dev Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, James Morse , Alexandru Elisei , Zenghui Yu , Suzuki K Poulose , Paolo Bonzini , Ricardo Koller , Jing Zhang , Raghavendra Rao Anata , Shaoqin Huang , Rob Herring , Reiji Watanabe X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230415_094110_745404_4D2BBFAC X-CRM114-Status: GOOD ( 26.71 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Currently, with VHE, KVM sets ER, CR, SW and EN bits of PMUSERENR_EL0 to 1 on vcpu_load(), and saves and restores the register value for the host on vcpu_load() and vcpu_put(). If the value of those bits are cleared on a pCPU with a vCPU loaded (armv8pmu_start() would do that when PMU counters are programmed for the guest), PMU access from the guest EL0 might be trapped to the guest EL1 directly regardless of the current PMUSERENR_EL0 value of the vCPU. Fix this by not letting armv8pmu_start() overwrite PMUSERENR_EL0 on the pCPU where PMUSERENR_EL0 for the guest is loaded, and instead updating the saved shadow register value for the host, so that the value can be restored on vcpu_put() later. While vcpu_{put,load}() are manipulating PMUSERENR_EL0, disable IRQs to prevent a race condition between these processes and IPIs that attempt to update PMUSERENR_EL0 for the host EL0. As this change (disabling IRQs) is applied to the nVHE hyp code, unwanted code (i.e. trace_hardirqs_off) will be included in the hyp code when CONFIG_TRACE_IRQFLAGS is enabled. Introduce NO_TRACE_IRQFLAGS macro to locally disable CONFIG_TRACE_IRQFLAGS in the nVHE hyp code. Suggested-by: Mark Rutland Suggested-by: Marc Zyngier Fixes: 83a7a4d643d3 ("arm64: perf: Enable PMU counter userspace access for perf event") Signed-off-by: Reiji Watanabe --- arch/arm64/include/asm/kvm_host.h | 7 +++++++ arch/arm64/kernel/perf_event.c | 21 ++++++++++++++++++--- arch/arm64/kvm/hyp/include/hyp/switch.h | 24 ++++++++++++++++++++++++ arch/arm64/kvm/hyp/nvhe/Makefile | 2 +- arch/arm64/kvm/pmu.c | 25 +++++++++++++++++++++++++ include/linux/irqflags.h | 4 ++-- 6 files changed, 77 insertions(+), 6 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index bcd774d74f34..c49cfda2740a 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -668,6 +668,8 @@ struct kvm_vcpu_arch { /* Software step state is Active-pending */ #define DBG_SS_ACTIVE_PENDING __vcpu_single_flag(sflags, BIT(5)) +/* PMUSERENR for the guest EL0 is on physical CPU */ +#define PMUSERENR_ON_CPU __vcpu_single_flag(sflags, BIT(6)) /* Pointer to the vcpu's SVE FFR for sve_{save,load}_state() */ #define vcpu_sve_pffr(vcpu) (kern_hyp_va((vcpu)->arch.sve_state) + \ @@ -1028,9 +1030,14 @@ void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu); #ifdef CONFIG_KVM void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr); void kvm_clr_pmu_events(u32 clr); +bool kvm_set_pmuserenr(u64 val); #else static inline void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr) {} static inline void kvm_clr_pmu_events(u32 clr) {} +static inline bool kvm_set_pmuserenr(u64 val) +{ + return false; +} #endif void kvm_vcpu_load_sysregs_vhe(struct kvm_vcpu *vcpu); diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index dde06c0f97f3..33bb5f548f8a 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -741,9 +741,25 @@ static inline u32 armv8pmu_getreset_flags(void) return value; } +static void update_pmuserenr(u64 val) +{ + lockdep_assert_irqs_disabled(); + + /* + * The current PMUSERENR_EL0 value might be the value for the guest. + * If that's the case, have KVM keep tracking of the register value + * for the host EL0 so that KVM can restore it before returning to + * the host EL0. Otherwise, update the register now. + */ + if (kvm_set_pmuserenr(val)) + return; + + write_sysreg(val, pmuserenr_el0); +} + static void armv8pmu_disable_user_access(void) { - write_sysreg(0, pmuserenr_el0); + update_pmuserenr(0); } static void armv8pmu_enable_user_access(struct arm_pmu *cpu_pmu) @@ -759,8 +775,7 @@ static void armv8pmu_enable_user_access(struct arm_pmu *cpu_pmu) armv8pmu_write_evcntr(i, 0); } - write_sysreg(0, pmuserenr_el0); - write_sysreg(ARMV8_PMU_USERENR_ER | ARMV8_PMU_USERENR_CR, pmuserenr_el0); + update_pmuserenr(ARMV8_PMU_USERENR_ER | ARMV8_PMU_USERENR_CR); } static void armv8pmu_enable_event(struct perf_event *event) diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h index 6718731729fd..7e73be12cfaf 100644 --- a/arch/arm64/kvm/hyp/include/hyp/switch.h +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h @@ -82,12 +82,24 @@ static inline void __activate_traps_common(struct kvm_vcpu *vcpu) */ if (kvm_arm_support_pmu_v3()) { struct kvm_cpu_context *hctxt; + unsigned long flags; write_sysreg(0, pmselr_el0); hctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt; + + /* + * Disable IRQs to prevent a race condition between the + * following code and IPIs that attempts to update + * PMUSERENR_EL0. See also kvm_set_pmuserenr(). + */ + local_irq_save(flags); + ctxt_sys_reg(hctxt, PMUSERENR_EL0) = read_sysreg(pmuserenr_el0); write_sysreg(ARMV8_PMU_USERENR_MASK, pmuserenr_el0); + vcpu_set_flag(vcpu, PMUSERENR_ON_CPU); + + local_irq_restore(flags); } vcpu->arch.mdcr_el2_host = read_sysreg(mdcr_el2); @@ -112,9 +124,21 @@ static inline void __deactivate_traps_common(struct kvm_vcpu *vcpu) write_sysreg(0, hstr_el2); if (kvm_arm_support_pmu_v3()) { struct kvm_cpu_context *hctxt; + unsigned long flags; hctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt; + + /* + * Disable IRQs to prevent a race condition between the + * following code and IPIs that attempts to update + * PMUSERENR_EL0. See also kvm_set_pmuserenr(). + */ + local_irq_save(flags); + write_sysreg(ctxt_sys_reg(hctxt, PMUSERENR_EL0), pmuserenr_el0); + vcpu_clear_flag(vcpu, PMUSERENR_ON_CPU); + + local_irq_restore(flags); } if (cpus_have_final_cap(ARM64_SME)) { diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile index 530347cdebe3..2c08a54ca7d9 100644 --- a/arch/arm64/kvm/hyp/nvhe/Makefile +++ b/arch/arm64/kvm/hyp/nvhe/Makefile @@ -10,7 +10,7 @@ asflags-y := -D__KVM_NVHE_HYPERVISOR__ -D__DISABLE_EXPORTS # will explode instantly (Words of Marc Zyngier). So introduce a generic flag # __DISABLE_TRACE_MMIO__ to disable MMIO tracing for nVHE KVM. ccflags-y := -D__KVM_NVHE_HYPERVISOR__ -D__DISABLE_EXPORTS -D__DISABLE_TRACE_MMIO__ -ccflags-y += -fno-stack-protector \ +ccflags-y += -fno-stack-protector -DNO_TRACE_IRQFLAGS \ -DDISABLE_BRANCH_PROFILING \ $(DISABLE_STACKLEAK_PLUGIN) diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c index 7887133d15f0..d6a863853bfe 100644 --- a/arch/arm64/kvm/pmu.c +++ b/arch/arm64/kvm/pmu.c @@ -209,3 +209,28 @@ void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu) kvm_vcpu_pmu_enable_el0(events_host); kvm_vcpu_pmu_disable_el0(events_guest); } + +/* + * With VHE, keep track of the PMUSERENR_EL0 value for the host EL0 on the pCPU + * where PMUSERENR_EL0 for the guest is loaded, since PMUSERENR_EL0 is switched + * to the value for the guest on vcpu_load(). The value for the host EL0 + * will be restored on vcpu_put(), before returning to the EL0. + * + * Return true if KVM takes care of the register. Otherwise return false. + */ +bool kvm_set_pmuserenr(u64 val) +{ + struct kvm_cpu_context *hctxt; + struct kvm_vcpu *vcpu; + + if (!kvm_arm_support_pmu_v3() || !has_vhe()) + return false; + + vcpu = kvm_get_running_vcpu(); + if (!vcpu || !vcpu_get_flag(vcpu, PMUSERENR_ON_CPU)) + return false; + + hctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt; + ctxt_sys_reg(hctxt, PMUSERENR_EL0) = val; + return true; +} diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h index 5ec0fa71399e..f7fd5d645b52 100644 --- a/include/linux/irqflags.h +++ b/include/linux/irqflags.h @@ -198,9 +198,9 @@ extern void warn_bogus_irq_restore(void); /* * The local_irq_*() APIs are equal to the raw_local_irq*() - * if !TRACE_IRQFLAGS. + * if !TRACE_IRQFLAGS or if NO_TRACE_IRQFLAGS is locally set. */ -#ifdef CONFIG_TRACE_IRQFLAGS +#if defined CONFIG_TRACE_IRQFLAGS && !defined(NO_TRACE_IRQFLAGS) #define local_irq_enable() \ do { \