Currently, KVM uses the sanitized value of ID_AA64DFR0_EL1.PMUVer
as the default value and the limit value of this field for
vCPUs with PMU configured. But, the sanitized value could
be inappropriate for the vCPUs on some heterogeneous PMU systems,
as arm64_ftr_bits for PMUVer is defined as FTR_EXACT with
safe_val == 0 (if the ID_AA64DFR0_EL1.PMUVer of all PEs on the
host is not uniform, the sanitized value will be 0).
Use the PMUver of the guest's PMU (kvm->arch.arm_pmu->pmuver) as the
default value and the limit value of ID_AA64DFR0_EL1.PMUVer for vCPUs
with PMU configured.
When the guest's PMU is switched to a different PMU, reset
the value of ID_AA64DFR0_EL1.PMUVer for the vCPUs based on
the new PMU, unless userspace has already modified the PMUVer
and the value is still valid even with the new PMU.
Signed-off-by: Reiji Watanabe <reijiw@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_host.h | 2 ++
arch/arm64/kvm/arm.c | 6 ----
arch/arm64/kvm/pmu-emul.c | 28 +++++++++++++-----
arch/arm64/kvm/sys_regs.c | 48 ++++++++++++++++++++-----------
include/kvm/arm_pmu.h | 4 +--
5 files changed, 57 insertions(+), 31 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 7e7e19ef6993..8ca0e7210a59 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -231,6 +231,8 @@ struct kvm_arch {
#define KVM_ARCH_FLAG_TIMER_PPIS_IMMUTABLE 7
/* SMCCC filter initialized for the VM */
#define KVM_ARCH_FLAG_SMCCC_FILTER_CONFIGURED 8
+ /* PMUVer set by userspace for the VM */
+#define KVM_ARCH_FLAG_PMUVER_DIRTY 9
unsigned long flags;
/*
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 14391826241c..3c2fddfe90f7 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -164,12 +164,6 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
set_default_spectre(kvm);
kvm_arm_init_hypercalls(kvm);
- /*
- * Initialise the default PMUver before there is a chance to
- * create an actual PMU.
- */
- kvm->arch.dfr0_pmuver.imp = kvm_arm_pmu_get_pmuver_limit();
-
return 0;
err_free_cpumask:
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 0194a94c4bae..6cd08d5e5b72 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -871,6 +871,8 @@ static bool pmu_irq_is_valid(struct kvm *kvm, int irq)
int kvm_arm_set_vm_pmu(struct kvm *kvm, struct arm_pmu *arm_pmu)
{
+ u8 new_limit;
+
lockdep_assert_held(&kvm->arch.config_lock);
if (!arm_pmu) {
@@ -880,6 +882,22 @@ int kvm_arm_set_vm_pmu(struct kvm *kvm, struct arm_pmu *arm_pmu)
}
kvm->arch.arm_pmu = arm_pmu;
+ new_limit = kvm_arm_pmu_get_pmuver_limit(kvm);
+
+ /*
+ * Reset the value of ID_AA64DFR0_EL1.PMUVer to the new limit value,
+ * unless the current value was set by userspace and is still a valid
+ * value for the new PMU.
+ */
+ if (!test_bit(KVM_ARCH_FLAG_PMUVER_DIRTY, &kvm->arch.flags)) {
+ kvm->arch.dfr0_pmuver.imp = new_limit;
+ return 0;
+ }
+
+ if (kvm->arch.dfr0_pmuver.imp > new_limit) {
+ kvm->arch.dfr0_pmuver.imp = new_limit;
+ clear_bit(KVM_ARCH_FLAG_PMUVER_DIRTY, &kvm->arch.flags);
+ }
return 0;
}
@@ -1049,13 +1067,9 @@ int kvm_arm_pmu_v3_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
return -ENXIO;
}
-u8 kvm_arm_pmu_get_pmuver_limit(void)
+u8 kvm_arm_pmu_get_pmuver_limit(struct kvm *kvm)
{
- u64 tmp;
+ u8 host_pmuver = kvm->arch.arm_pmu ? kvm->arch.arm_pmu->pmuver : 0;
- tmp = read_sanitised_ftr_reg(SYS_ID_AA64DFR0_EL1);
- tmp = cpuid_feature_cap_perfmon_field(tmp,
- ID_AA64DFR0_EL1_PMUVer_SHIFT,
- ID_AA64DFR0_EL1_PMUVer_V3P5);
- return FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer), tmp);
+ return min_t(u8, host_pmuver, ID_AA64DFR0_EL1_PMUVer_V3P5);
}
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 71b12094d613..a76155ad997c 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1382,8 +1382,11 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
{
u8 pmuver, host_pmuver;
bool valid_pmu;
+ u64 current_val = read_id_reg(vcpu, rd);
+ int ret = -EINVAL;
- host_pmuver = kvm_arm_pmu_get_pmuver_limit();
+ mutex_lock(&vcpu->kvm->arch.config_lock);
+ host_pmuver = kvm_arm_pmu_get_pmuver_limit(vcpu->kvm);
/*
* Allow AA64DFR0_EL1.PMUver to be set from userspace as long
@@ -1393,26 +1396,31 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
*/
pmuver = FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer), val);
if ((pmuver != ID_AA64DFR0_EL1_PMUVer_IMP_DEF && pmuver > host_pmuver))
- return -EINVAL;
+ goto out;
valid_pmu = (pmuver != 0 && pmuver != ID_AA64DFR0_EL1_PMUVer_IMP_DEF);
/* Make sure view register and PMU support do match */
if (kvm_vcpu_has_pmu(vcpu) != valid_pmu)
- return -EINVAL;
+ goto out;
/* We can only differ with PMUver, and anything else is an error */
- val ^= read_id_reg(vcpu, rd);
+ val ^= current_val;
val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer);
if (val)
- return -EINVAL;
+ goto out;
- if (valid_pmu)
+ if (valid_pmu) {
vcpu->kvm->arch.dfr0_pmuver.imp = pmuver;
- else
+ set_bit(KVM_ARCH_FLAG_PMUVER_DIRTY, &vcpu->kvm->arch.flags);
+ } else
vcpu->kvm->arch.dfr0_pmuver.unimp = pmuver;
- return 0;
+ ret = 0;
+out:
+ mutex_unlock(&vcpu->kvm->arch.config_lock);
+
+ return ret;
}
static int set_id_dfr0_el1(struct kvm_vcpu *vcpu,
@@ -1421,8 +1429,11 @@ static int set_id_dfr0_el1(struct kvm_vcpu *vcpu,
{
u8 perfmon, host_perfmon;
bool valid_pmu;
+ u64 current_val = read_id_reg(vcpu, rd);
+ int ret = -EINVAL;
- host_perfmon = pmuver_to_perfmon(kvm_arm_pmu_get_pmuver_limit());
+ mutex_lock(&vcpu->kvm->arch.config_lock);
+ host_perfmon = pmuver_to_perfmon(kvm_arm_pmu_get_pmuver_limit(vcpu->kvm));
/*
* Allow DFR0_EL1.PerfMon to be set from userspace as long as
@@ -1433,26 +1444,31 @@ static int set_id_dfr0_el1(struct kvm_vcpu *vcpu,
perfmon = FIELD_GET(ARM64_FEATURE_MASK(ID_DFR0_EL1_PerfMon), val);
if ((perfmon != ID_DFR0_EL1_PerfMon_IMPDEF && perfmon > host_perfmon) ||
(perfmon != 0 && perfmon < ID_DFR0_EL1_PerfMon_PMUv3))
- return -EINVAL;
+ goto out;
valid_pmu = (perfmon != 0 && perfmon != ID_DFR0_EL1_PerfMon_IMPDEF);
/* Make sure view register and PMU support do match */
if (kvm_vcpu_has_pmu(vcpu) != valid_pmu)
- return -EINVAL;
+ goto out;
/* We can only differ with PerfMon, and anything else is an error */
- val ^= read_id_reg(vcpu, rd);
+ val ^= current_val;
val &= ~ARM64_FEATURE_MASK(ID_DFR0_EL1_PerfMon);
if (val)
- return -EINVAL;
+ goto out;
- if (valid_pmu)
+ if (valid_pmu) {
vcpu->kvm->arch.dfr0_pmuver.imp = perfmon_to_pmuver(perfmon);
- else
+ set_bit(KVM_ARCH_FLAG_PMUVER_DIRTY, &vcpu->kvm->arch.flags);
+ } else
vcpu->kvm->arch.dfr0_pmuver.unimp = perfmon_to_pmuver(perfmon);
- return 0;
+ ret = 0;
+out:
+ mutex_unlock(&vcpu->kvm->arch.config_lock);
+
+ return ret;
}
/*
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 5ece2a3c1858..00c05d17cf3a 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -95,7 +95,7 @@ void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu);
#define kvm_pmu_is_3p5(vcpu) \
(vcpu->kvm->arch.dfr0_pmuver.imp >= ID_AA64DFR0_EL1_PMUVer_V3P5)
-u8 kvm_arm_pmu_get_pmuver_limit(void);
+u8 kvm_arm_pmu_get_pmuver_limit(struct kvm *kvm);
int kvm_arm_set_vm_pmu(struct kvm *kvm, struct arm_pmu *arm_pmu);
#else
@@ -164,7 +164,7 @@ static inline u64 kvm_pmu_get_pmceid(struct kvm_vcpu *vcpu, bool pmceid1)
static inline void kvm_pmu_update_vcpu_events(struct kvm_vcpu *vcpu) {}
static inline void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu) {}
static inline void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu) {}
-static inline u8 kvm_arm_pmu_get_pmuver_limit(void)
+static inline u8 kvm_arm_pmu_get_pmuver_limit(struct kvm *kvm)
{
return 0;
}
--
2.41.0.rc0.172.g3f132b7071-goog
