Commit 166b77a2 authored by Oliver Upton's avatar Oliver Upton
Browse files

KVM: arm64: nv: Advertise support for FEAT_HPMN0 



Everything is in place now for KVM to actually handle MDCR_EL2.HPMN. Not
only that, the emulation is capable of doing FEAT_HPMN0. Advertise
support for the feature in the VM's ID registers. It is possible to
emulate FEAT_HPMN0 on hardware that doesn't support it since KVM
currently traps all PMU registers. Having said that, let's only
advertise the feature on supporting hardware in case KVM ever provides
'direct' PMU support to VMs w/o involving host perf.

Reviewed-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241025182354.3364124-12-oliver.upton@linux.dev


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent 336afe0c

arch/arm64/kvm/nested.c

+3 −2
Original line number Diff line number Diff line
@@ -917,12 +917,13 @@ static void limit_nv_id_regs(struct kvm *kvm) 
				  ID_AA64MMFR4_EL1_E2H0_NI_NV1);

	kvm_set_vm_id_reg(kvm, SYS_ID_AA64MMFR4_EL1, val);



	/* Only limited support for PMU, Debug, BPs and WPs */

	/* Only limited support for PMU, Debug, BPs, WPs, and HPMN0 */

	val = kvm_read_vm_id_reg(kvm, SYS_ID_AA64DFR0_EL1);

	val &= (NV_FTR(DFR0, PMUVer)	|

		NV_FTR(DFR0, WRPs)	|

		NV_FTR(DFR0, BRPs)	|

		NV_FTR(DFR0, DebugVer));

		NV_FTR(DFR0, DebugVer)	|

		NV_FTR(DFR0, HPMN0));



	/* Cap Debug to ARMv8.1 */

	tmp = FIELD_GET(NV_FTR(DFR0, DebugVer), val);