linux-kernel - Re: [PATCH V3] arm64/boot: Enable EL2 requirements for FEAT

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Message-ID: <06140631-c3cb-4837-bb4c-bdff30863ad2@arm.com>
Date: Tue, 29 Apr 2025 11:07:28 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: Catalin Marinas <catalin.marinas@....com>,
 linux-arm-kernel@...ts.infradead.org, mark.rutland@....com, robh@...nel.org
Cc: Will Deacon <will@...nel.org>, Jonathan Corbet <corbet@....net>,
 Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 kvmarm@...ts.linux.dev, stable@...r.kernel.org
Subject: Re: [PATCH V3] arm64/boot: Enable EL2 requirements for FEAT_PMUv3p9



On 3/12/25 09:16, Anshuman Khandual wrote:
> 
> 
> On 3/11/25 22:47, Catalin Marinas wrote:
>> On Thu, 27 Feb 2025 09:21:19 +0530, Anshuman Khandual wrote:
>>> FEAT_PMUv3p9 registers such as PMICNTR_EL0, PMICFILTR_EL0, and PMUACR_EL1
>>> access from EL1 requires appropriate EL2 fine grained trap configuration
>>> via FEAT_FGT2 based trap control registers HDFGRTR2_EL2 and HDFGWTR2_EL2.
>>> Otherwise such register accesses will result in traps into EL2.
>>>
>>> Add a new helper __init_el2_fgt2() which initializes FEAT_FGT2 based fine
>>> grained trap control registers HDFGRTR2_EL2 and HDFGWTR2_EL2 (setting the
>>> bits nPMICNTR_EL0, nPMICFILTR_EL0 and nPMUACR_EL1) to enable access into
>>> PMICNTR_EL0, PMICFILTR_EL0, and PMUACR_EL1 registers.
>>>
>>> [...]
>>
>> Applied to arm64 (for-next/el2-enable-feat-pmuv3p9), thanks!
>>
>> [1/1] arm64/boot: Enable EL2 requirements for FEAT_PMUv3p9
>>       https://git.kernel.org/arm64/c/858c7bfcb35e
>>
>> I removed Cc: stable since, if it gets backported automatically, it will
>> miss the sysreg updates and break the build. Please send it to stable
>> directly once it lands upstream, together with the dependencies.
> 
> Sure, will do that.
> 

Just FYI,

This patch along with required tools sysreg patches are merged in applicable
stable branches which are now available in v6.12.25 and v6.14.4 respectively.