Commit 2e30447b authored Mar 05, 2026 by James Clark Committed by Will Deacon Mar 24, 2026

KVM: arm64: Read PMUVer as unsigned



ID_AA64DFR0_EL1.PMUVer is an unsigned field, so this skips
initialization of host_data_ptr(nr_event_counters) for PMUv3 for Armv8.8
onwards as they appear as negative values.

Fix it by reading it as unsigned. Now ID_AA64DFR0_EL1_PMUVer_IMP_DEF
needs to be special cased, so use pmuv3_implemented() which already does
it.

Fixes: 2417218f ("KVM: arm64: Get rid of __kvm_get_mdcr_el2() and related warts")
Signed-off-by: James Clark <james.clark@linaro.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Colton Lewis <coltonlewis@google.com>
Signed-off-by: Will Deacon <will@kernel.org>

parent 1f318b96

arch/arm64/kvm/debug.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -10,6 +10,7 @@
		#include <linux/kvm_host.h>
		#include <linux/hw_breakpoint.h>

		#include <asm/arm_pmuv3.h>
		#include <asm/debug-monitors.h>
		#include <asm/kvm_asm.h>
		#include <asm/kvm_arm.h>
		@@ -75,8 +76,10 @@ static void kvm_arm_setup_mdcr_el2(struct kvm_vcpu *vcpu)
		void kvm_init_host_debug_data(void)
		{
		u64 dfr0 = read_sysreg(id_aa64dfr0_el1);
		unsigned int pmuver = cpuid_feature_extract_unsigned_field(dfr0,
		ID_AA64DFR0_EL1_PMUVer_SHIFT);

		if (cpuid_feature_extract_signed_field(dfr0, ID_AA64DFR0_EL1_PMUVer_SHIFT) > 0)
		if (pmuv3_implemented(pmuver))
		*host_data_ptr(nr_event_counters) = FIELD_GET(ARMV8_PMU_PMCR_N,
		read_sysreg(pmcr_el0));