[PATCH V2] KVM: arm64: perf: Replace '0xf' instances with ID_AA64DFR0_PMUVER_IMP_DEF

[PATCH V2] KVM: arm64: perf: Replace '0xf' instances with ID_AA64DFR0_PMUVER_IMP_DEF

[Anshuman Khandual]

ID_AA64DFR0_PMUVER_IMP_DEF which indicate implementation defined PMU, never
actually gets used although there are '0xf' instances scattered all around.
Just do the macro replacement to improve readability.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: linux-perf-users@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: kvmarm@lists.cs.columbia.edu
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
This applies on v5.14-rc5

Changes in V2:

- Split out the KVM part

Changes in V1:

https://lore.kernel.org/linux-perf-users/1628571998-13634-1-git-send-email-anshuman.khandual@arm.com/

 arch/arm64/kvm/perf.c     | 2 +-
 arch/arm64/kvm/pmu-emul.c | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
index 151c31fb9860..f9bb3b14130e 100644
--- a/arch/arm64/kvm/perf.c
+++ b/arch/arm64/kvm/perf.c
@@ -50,7 +50,7 @@ static struct perf_guest_info_callbacks kvm_guest_cbs = {
 
 int kvm_perf_init(void)
 {
-	if (kvm_pmu_probe_pmuver() != 0xf && !is_protected_kvm_enabled())
+	if (kvm_pmu_probe_pmuver() != ID_AA64DFR0_PMUVER_IMP_DEF && !is_protected_kvm_enabled())
 		static_branch_enable(&kvm_arm_pmu_available);
 
 	return perf_register_guest_info_callbacks(&kvm_guest_cbs);
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index f33825c995cb..60f89bdbeebb 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -745,7 +745,7 @@ int kvm_pmu_probe_pmuver(void)
 	struct perf_event_attr attr = { };
 	struct perf_event *event;
 	struct arm_pmu *pmu;
-	int pmuver = 0xf;
+	int pmuver = ID_AA64DFR0_PMUVER_IMP_DEF;
 
 	/*
 	 * Create a dummy event that only counts user cycles. As we'll never
@@ -770,7 +770,7 @@ int kvm_pmu_probe_pmuver(void)
 	if (IS_ERR(event)) {
 		pr_err_once("kvm: pmu event creation failed %ld\n",
 			    PTR_ERR(event));
-		return 0xf;
+		return ID_AA64DFR0_PMUVER_IMP_DEF;
 	}
 
 	if (event->pmu) {
@@ -923,7 +923,7 @@ int kvm_arm_pmu_v3_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
 	if (!vcpu->kvm->arch.pmuver)
 		vcpu->kvm->arch.pmuver = kvm_pmu_probe_pmuver();
 
-	if (vcpu->kvm->arch.pmuver == 0xf)
+	if (vcpu->kvm->arch.pmuver == ID_AA64DFR0_PMUVER_IMP_DEF)
 		return -ENODEV;
 
 	switch (attr->attr) {
-- 
2.20.1

[PATCH V2] arm64/perf: Replace '0xf' instances with ID_AA64DFR0_PMUVER_IMP_DEF

[Anshuman Khandual]

ID_AA64DFR0_PMUVER_IMP_DEF which indicate implementation defined PMU, never
actually gets used although there are '0xf' instances scattered all around.
Just do the macro replacement to improve readability.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-perf-users@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
This applies on v5.14-rc5

Changes in V2:

- Split out the arm64 part

Changes in V1:

https://lore.kernel.org/linux-perf-users/1628571998-13634-1-git-send-email-anshuman.khandual@arm.com/

 arch/arm64/include/asm/cpufeature.h | 2 +-
 arch/arm64/kernel/perf_event.c      | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 9bb9d11750d7..54474e76ad86 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -552,7 +552,7 @@ cpuid_feature_cap_perfmon_field(u64 features, int field, u64 cap)
 	u64 mask = GENMASK_ULL(field + 3, field);
 
 	/* Treat IMPLEMENTATION DEFINED functionality as unimplemented */
-	if (val == 0xf)
+	if (val == ID_AA64DFR0_PMUVER_IMP_DEF)
 		val = 0;
 
 	if (val > cap) {
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index d07788dad388..b4044469527e 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -1055,7 +1055,7 @@ static void __armv8pmu_probe_pmu(void *info)
 	dfr0 = read_sysreg(id_aa64dfr0_el1);
 	pmuver = cpuid_feature_extract_unsigned_field(dfr0,
 			ID_AA64DFR0_PMUVER_SHIFT);
-	if (pmuver == 0xf || pmuver == 0)
+	if (pmuver == ID_AA64DFR0_PMUVER_IMP_DEF || pmuver == 0)
 		return;
 
 	cpu_pmu->pmuver = pmuver;
-- 
2.20.1

Re: [PATCH V2] KVM: arm64: perf: Replace '0xf' instances with ID_AA64DFR0_PMUVER_IMP_DEF

[Marc Zyngier]

On Wed, 11 Aug 2021 04:27:06 +0100,
Anshuman Khandual <anshuman.khandual@arm.com> wrote:
> 
> ID_AA64DFR0_PMUVER_IMP_DEF which indicate implementation defined PMU, never
> actually gets used although there are '0xf' instances scattered all around.
> Just do the macro replacement to improve readability.
> 
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: linux-perf-users@vger.kernel.org
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: kvmarm@lists.cs.columbia.edu
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>

For some reason I don't understand, b4 doesn't want to cherry-pick
this patch from the list. I've applied it manually to
kvm-arm64/misc-5.15.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH V2] arm64/perf: Replace '0xf' instances with ID_AA64DFR0_PMUVER_IMP_DEF

[Will Deacon]

On Wed, 11 Aug 2021 08:57:07 +0530, Anshuman Khandual wrote:
> ID_AA64DFR0_PMUVER_IMP_DEF which indicate implementation defined PMU, never
> actually gets used although there are '0xf' instances scattered all around.
> Just do the macro replacement to improve readability.

Applied to will (for-next/perf), thanks!

[1/1] arm64/perf: Replace '0xf' instances with ID_AA64DFR0_PMUVER_IMP_DEF
      https://git.kernel.org/will/c/fd264b310579

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev