KVM: arm64: Add minimal handling for the ARMv8.7 PMU

When running a KVM guest hosted on an ARMv8.7 machine, the host
kernel complains that it doesn't know about the architected number
of events.

Fix it by adding the PMUver code corresponding to PMUv3 for ARMv8.7.
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Tested-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211126115533.217903-1-maz@kernel.org

arch/arm64/include/asm/sysreg.h

@@ -937,6 +937,7 @@
 #define ID_AA64DFR0_PMUVER_8_1		0x4
 #define ID_AA64DFR0_PMUVER_8_4		0x5
 #define ID_AA64DFR0_PMUVER_8_5		0x6
+#define ID_AA64DFR0_PMUVER_8_7		0x7
 #define ID_AA64DFR0_PMUVER_IMP_DEF	0xf
 
 #define ID_AA64DFR0_PMSVER_8_2		0x1

arch/arm64/kvm/pmu-emul.c

@@ -28,6 +28,7 @@ static u32 kvm_pmu_event_mask(struct kvm *kvm)
 	case ID_AA64DFR0_PMUVER_8_1:
 	case ID_AA64DFR0_PMUVER_8_4:
 	case ID_AA64DFR0_PMUVER_8_5:
+	case ID_AA64DFR0_PMUVER_8_7:
 		return GENMASK(15, 0);
 	default:		/* Shouldn't be here, just for sanity */
 		WARN_ONCE(1, "Unknown PMU version %d\n", kvm->arch.pmuver);