The SPE driver allows userspace to use physical timestamps for records only
if the process if perfmon_capable(). Do the same for a virtual machine with
the SPE feature.
Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
---
arch/arm64/include/asm/kvm_host.h | 2 ++
arch/arm64/include/asm/kvm_spe.h | 7 +++++++
arch/arm64/kvm/hyp/nvhe/spe-sr.c | 2 +-
arch/arm64/kvm/hyp/vhe/spe-sr.c | 2 +-
arch/arm64/kvm/spe.c | 14 ++++++++++++++
5 files changed, 25 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 66f0b999cb5f..cc46f1406196 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -157,6 +157,8 @@ struct kvm_arch {
/* Memory Tagging Extension enabled for the guest */
bool mte_enabled;
+
+ struct kvm_spe spe;
};
struct kvm_vcpu_fault_info {
diff --git a/arch/arm64/include/asm/kvm_spe.h b/arch/arm64/include/asm/kvm_spe.h
index 6b8d4cf2cd37..272f1eec64f2 100644
--- a/arch/arm64/include/asm/kvm_spe.h
+++ b/arch/arm64/include/asm/kvm_spe.h
@@ -21,6 +21,10 @@ struct kvm_vcpu_spe {
int irq_num; /* Buffer management interrut number */
};
+struct kvm_spe {
+ bool perfmon_capable; /* Is the VM perfmon_capable()? */
+};
+
void kvm_spe_init_supported_cpus(void);
void kvm_spe_vm_init(struct kvm *kvm);
int kvm_spe_vcpu_first_run_init(struct kvm_vcpu *vcpu);
@@ -41,6 +45,9 @@ int kvm_spe_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr);
struct kvm_vcpu_spe {
};
+struct kvm_spe {
+};
+
static inline void kvm_spe_init_supported_cpus(void) {}
static inline void kvm_spe_vm_init(struct kvm *kvm) {}
static inline int kvm_spe_vcpu_first_run_init(struct kvm_vcpu *vcpu) { return -ENOEXEC; }
diff --git a/arch/arm64/kvm/hyp/nvhe/spe-sr.c b/arch/arm64/kvm/hyp/nvhe/spe-sr.c
index 46e47c9fd08f..4f6579daddb5 100644
--- a/arch/arm64/kvm/hyp/nvhe/spe-sr.c
+++ b/arch/arm64/kvm/hyp/nvhe/spe-sr.c
@@ -83,5 +83,5 @@ void __spe_restore_guest_state_nvhe(struct kvm_vcpu *vcpu,
write_sysreg_s(ctxt_sys_reg(guest_ctxt, PMBSR_EL1), SYS_PMBSR_EL1);
write_sysreg_s(ctxt_sys_reg(guest_ctxt, PMBLIMITR_EL1), SYS_PMBLIMITR_EL1);
write_sysreg_s(ctxt_sys_reg(guest_ctxt, PMSCR_EL1), SYS_PMSCR_EL1);
- write_sysreg_el2(0, SYS_PMSCR);
+ write_sysreg_el2(ctxt_sys_reg(guest_ctxt, PMSCR_EL2), SYS_PMSCR);
}
diff --git a/arch/arm64/kvm/hyp/vhe/spe-sr.c b/arch/arm64/kvm/hyp/vhe/spe-sr.c
index 00eab9e2ec60..f557ac64a1cc 100644
--- a/arch/arm64/kvm/hyp/vhe/spe-sr.c
+++ b/arch/arm64/kvm/hyp/vhe/spe-sr.c
@@ -21,7 +21,7 @@ void __spe_save_host_state_vhe(struct kvm_vcpu *vcpu,
/* Disable profiling while the SPE context is being switched. */
pmscr_el2 = read_sysreg_el2(SYS_PMSCR);
- write_sysreg_el2(0, SYS_PMSCR);
+ write_sysreg_el2(__vcpu_sys_reg(vcpu, PMSCR_EL2), SYS_PMSCR);
isb();
pmblimitr = read_sysreg_s(SYS_PMBLIMITR_EL1);
diff --git a/arch/arm64/kvm/spe.c b/arch/arm64/kvm/spe.c
index 711736c49f63..054bb16bbd79 100644
--- a/arch/arm64/kvm/spe.c
+++ b/arch/arm64/kvm/spe.c
@@ -3,6 +3,7 @@
* Copyright (C) 2021 - ARM Ltd
*/
+#include <linux/capability.h>
#include <linux/cpumask.h>
#include <linux/kvm_host.h>
#include <linux/perf/arm_pmu.h>
@@ -29,6 +30,16 @@ void kvm_spe_vm_init(struct kvm *kvm)
{
/* Set supported_cpus if it isn't already initialized. */
kvm_spe_init_supported_cpus();
+
+ /*
+ * Allow the guest to use the physical timer for timestamps only if the
+ * VMM is perfmon_capable(), similar to what the SPE driver allows.
+ *
+ * CAP_PERFMON can be changed during the lifetime of the VM, so record
+ * its value when the VM is created to avoid situations where only some
+ * VCPUs allow physical timer timestamps, while others don't.
+ */
+ kvm->arch.spe.perfmon_capable = perfmon_capable();
}
static int kvm_spe_check_supported_cpus(struct kvm_vcpu *vcpu)
@@ -54,6 +65,9 @@ int kvm_spe_vcpu_first_run_init(struct kvm_vcpu *vcpu)
if (!vcpu->arch.spe.initialized)
return -EPERM;
+ if (vcpu->kvm->arch.spe.perfmon_capable)
+ __vcpu_sys_reg(vcpu, PMSCR_EL2) = BIT(SYS_PMSCR_EL1_PCT_SHIFT);
+
return 0;
}
--
2.33.0
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