Hi Eric,
On 2021-01-27 17:53, Auger Eric wrote:
Hi Marc,
On 1/25/21 1:26 PM, Marc Zyngier wrote:
Upgrading the PMU code from ARMv8.1 to ARMv8.4 turns out to be
pretty easy. All that is required is support for PMMIR_EL1, which
is read-only, and for which returning 0 is a valid option as long
as we don't advertise STALL_SLOT as an implemented event.
Let's just do that and adjust what we return to the guest.
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
arch/arm64/include/asm/sysreg.h | 3 +++
arch/arm64/kvm/pmu-emul.c | 6 ++++++
arch/arm64/kvm/sys_regs.c | 11 +++++++----
3 files changed, 16 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/include/asm/sysreg.h
b/arch/arm64/include/asm/sysreg.h
index 8b5e7e5c3cc8..2fb3f386588c 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -846,7 +846,10 @@
#define ID_DFR0_PERFMON_SHIFT 24
+#define ID_DFR0_PERFMON_8_0 0x3
#define ID_DFR0_PERFMON_8_1 0x4
+#define ID_DFR0_PERFMON_8_4 0x5
+#define ID_DFR0_PERFMON_8_5 0x6
#define ID_ISAR4_SWP_FRAC_SHIFT 28
#define ID_ISAR4_PSR_M_SHIFT 24
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 398f6df1bbe4..72cd704a8368 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -795,6 +795,12 @@ u64 kvm_pmu_get_pmceid(struct kvm_vcpu *vcpu,
bool pmceid1)
base = 0;
} else {
val = read_sysreg(pmceid1_el0);
+ /*
+ * Don't advertise STALL_SLOT, as PMMIR_EL0 is handled
+ * as RAZ
+ */
+ if (vcpu->kvm->arch.pmuver >= ID_AA64DFR0_PMUVER_8_4)
+ val &= ~BIT_ULL(ARMV8_PMUV3_PERFCTR_STALL_SLOT - 32);
what about the STALL_SLOT_BACKEND and FRONTEND events then?
Aren't these a mandatory ARMv8.1 feature? I don't see a reason to
drop them.
base = 32;
}
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 8f79ec1fffa7..5da536ab738d 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1051,16 +1051,16 @@ static u64 read_id_reg(const struct kvm_vcpu
*vcpu,
/* Limit debug to ARMv8.0 */
val &= ~FEATURE(ID_AA64DFR0_DEBUGVER);
val |= FIELD_PREP(FEATURE(ID_AA64DFR0_DEBUGVER), 6);
- /* Limit guests to PMUv3 for ARMv8.1 */
+ /* Limit guests to PMUv3 for ARMv8.4 */
val = cpuid_feature_cap_perfmon_field(val,
ID_AA64DFR0_PMUVER_SHIFT,
- kvm_vcpu_has_pmu(vcpu) ? ID_AA64DFR0_PMUVER_8_1 : 0);
+ kvm_vcpu_has_pmu(vcpu) ? ID_AA64DFR0_PMUVER_8_4 : 0);
break;
case SYS_ID_DFR0_EL1:
- /* Limit guests to PMUv3 for ARMv8.1 */
+ /* Limit guests to PMUv3 for ARMv8.4 */
val = cpuid_feature_cap_perfmon_field(val,
ID_DFR0_PERFMON_SHIFT,
- kvm_vcpu_has_pmu(vcpu) ? ID_DFR0_PERFMON_8_1 : 0);
+ kvm_vcpu_has_pmu(vcpu) ? ID_DFR0_PERFMON_8_4 : 0);
break;
}
@@ -1496,6 +1496,7 @@ static const struct sys_reg_desc sys_reg_descs[]
= {
{ SYS_DESC(SYS_PMINTENSET_EL1), access_pminten, reset_unknown,
PMINTENSET_EL1 },
{ SYS_DESC(SYS_PMINTENCLR_EL1), access_pminten, reset_unknown,
PMINTENSET_EL1 },
"KVM: arm64: Hide PMU registers from userspace when not available"
changed the above, doesn't it?
Yes, that's because the fix didn't make it in mainline before
5.11-rc5, and I based this on -rc4. I'll fix it at merge time.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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