KVM: arm64: Pass pmu events to hyp via vcpu

Instead of the host accessing hyp data directly, pass the pmu
events of the current cpu to hyp via the vcpu.

This adds 64 bits (in two fields) to the vcpu that need to be
synced before every vcpu run in nvhe and protected modes.
However, it isolates the hypervisor from the host, which allows
us to use pmu in protected mode in a subsequent patch.

No visible side effects in behavior intended.

Signed-off-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220510095710.148178-4-tabba@google.com

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 94a27a7520f4740e64e202599c11fa75441b4e44..efca5a63bdaf89229b90b93f96eb9111536bb32f 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -254,14 +254,8 @@ struct kvm_cpu_context {
        struct kvm_vcpu *__hyp_running_vcpu;
 };
 
-struct kvm_pmu_events {
-       u32 events_host;
-       u32 events_guest;
-};
-
 struct kvm_host_data {
        struct kvm_cpu_context host_ctxt;
-       struct kvm_pmu_events pmu_events;
 };
 
 struct kvm_host_psci_config {
@@ -796,6 +790,7 @@ void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu);
 void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr);
 void kvm_clr_pmu_events(u32 clr);
 
+struct kvm_pmu_events *kvm_get_pmu_events(void);
 void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu);
 void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu);
 #else

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 523bc934fe2f66687b2bb605776f4b239b6114d3..aa1b15e9d5d9b5ca79b46401f7fc0358298dcebb 100644 (file)
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -751,6 +751,19 @@ static int noinstr kvm_arm_vcpu_enter_exit(struct kvm_vcpu *vcpu)
        return ret;
 }
 
+/*
+ * Updates the vcpu's view of the pmu events for this cpu.
+ * Must be called before every vcpu run after disabling interrupts, to ensure
+ * that an interrupt cannot fire and update the structure.
+ */
+static void kvm_pmu_update_vcpu_events(struct kvm_vcpu *vcpu)
+{
+       if (has_vhe() || !kvm_vcpu_has_pmu(vcpu))
+               return;
+
+       vcpu->arch.pmu.events = *kvm_get_pmu_events();
+}
+
 /**
  * kvm_arch_vcpu_ioctl_run - the main VCPU run function to execute guest code
  * @vcpu:      The VCPU pointer
@@ -815,6 +828,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 
                kvm_vgic_flush_hwstate(vcpu);
 
+               kvm_pmu_update_vcpu_events(vcpu);
+
                /*
                 * Ensure we set mode to IN_GUEST_MODE after we disable
                 * interrupts and before the final VCPU requests check.

diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 6410d21d86957d3b9e057e6412c2b91563e97c31..ff7b29fb978780b4c9fc44e49b6aa92b0f813efe 100644 (file)
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -123,13 +123,9 @@ static void __hyp_vgic_restore_state(struct kvm_vcpu *vcpu)
 /**
  * Disable host events, enable guest events
  */
-static bool __pmu_switch_to_guest(struct kvm_cpu_context *host_ctxt)
+static bool __pmu_switch_to_guest(struct kvm_vcpu *vcpu)
 {
-       struct kvm_host_data *host;
-       struct kvm_pmu_events *pmu;
-
-       host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);
-       pmu = &host->pmu_events;
+       struct kvm_pmu_events *pmu = &vcpu->arch.pmu.events;
 
        if (pmu->events_host)
                write_sysreg(pmu->events_host, pmcntenclr_el0);
@@ -143,13 +139,9 @@ static bool __pmu_switch_to_guest(struct kvm_cpu_context *host_ctxt)
 /**
  * Disable guest events, enable host events
  */
-static void __pmu_switch_to_host(struct kvm_cpu_context *host_ctxt)
+static void __pmu_switch_to_host(struct kvm_vcpu *vcpu)
 {
-       struct kvm_host_data *host;
-       struct kvm_pmu_events *pmu;
-
-       host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);
-       pmu = &host->pmu_events;
+       struct kvm_pmu_events *pmu = &vcpu->arch.pmu.events;
 
        if (pmu->events_guest)
                write_sysreg(pmu->events_guest, pmcntenclr_el0);
@@ -274,7 +266,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
        host_ctxt->__hyp_running_vcpu = vcpu;
        guest_ctxt = &vcpu->arch.ctxt;
 
-       pmu_switch_needed = __pmu_switch_to_guest(host_ctxt);
+       pmu_switch_needed = __pmu_switch_to_guest(vcpu);
 
        __sysreg_save_state_nvhe(host_ctxt);
        /*
@@ -336,7 +328,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
        __debug_restore_host_buffers_nvhe(vcpu);
 
        if (pmu_switch_needed)
-               __pmu_switch_to_host(host_ctxt);
+               __pmu_switch_to_host(vcpu);
 
        /* Returning to host will clear PSR.I, remask PMR if needed */
        if (system_uses_irq_prio_masking())

diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
index 4bd38ff3422167d76e42b90e2f1a19b27c9d3ed2..7887133d15f0b67f8b04c2c01b8c17ed2d9cb5d8 100644 (file)
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -5,7 +5,8 @@
  */
 #include <linux/kvm_host.h>
 #include <linux/perf_event.h>
-#include <asm/kvm_hyp.h>
+
+static DEFINE_PER_CPU(struct kvm_pmu_events, kvm_pmu_events);
 
 /*
  * Given the perf event attributes and system type, determine
@@ -25,14 +26,9 @@ static bool kvm_pmu_switch_needed(struct perf_event_attr *attr)
        return (attr->exclude_host != attr->exclude_guest);
 }
 
-static struct kvm_pmu_events *kvm_get_pmu_events(void)
+struct kvm_pmu_events *kvm_get_pmu_events(void)
 {
-       struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
-
-       if (!ctx)
-               return NULL;
-
-       return &ctx->pmu_events;
+       return this_cpu_ptr(&kvm_pmu_events);
 }
 
 /*

diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index eaa8290b116f98a1d5f150b74a7574337e5c45b7..35a0903cae321247b0bb263d3dfd349956b11c24 100644 (file)
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -20,8 +20,14 @@ struct kvm_pmc {
        struct perf_event *perf_event;
 };
 
+struct kvm_pmu_events {
+       u32 events_host;
+       u32 events_guest;
+};
+
 struct kvm_pmu {
        struct irq_work overflow_work;
+       struct kvm_pmu_events events;
        struct kvm_pmc pmc[ARMV8_PMU_MAX_COUNTERS];
        DECLARE_BITMAP(chained, ARMV8_PMU_MAX_COUNTER_PAIRS);
        int irq_num;