Hi Marc,

On 1/15/21 5:42 PM, Marc Zyngier wrote:

Hi Eric,

On 2021-01-15 14:01, Auger Eric wrote:

quoted

Hi Marc,

On 1/14/21 11:56 AM, Marc Zyngier wrote:

quoted

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.

Let's just do that and adjust what we return to the guest.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/sys_regs.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 8f79ec1fffa7..2f4ecbd2abfb 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c

@@ -1051,10 +1051,10 @@ 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 */

what about the debug version in aarch32 state. Is it on purpose that you
leave it as 8_1?

That's a good point. There is also the fact that we keep reporting
STALL_SLOT as a valid event even in PMCEID0_EL1 despite PMMIR_EL1.SLOTS
always reporting 0.

Hum OK. I did not notice that ;-)

Thanks

Eric

I'll fix that and resend something next week.

Thanks,

        M.

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