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Wed, 08 Jan 2025 11:15:13 +0000 Date: Wed, 08 Jan 2025 11:15:13 +0000 Message-ID: <86wmf5wo8u.wl-maz@kernel.org> From: Marc Zyngier To: Rob Herring Cc: Catalin Marinas , Anshuman Khandual , linux-arm-kernel@lists.infradead.org, Will Deacon , Ryan Roberts , Mark Rutland , Oliver Upton , Jonathan Corbet , Eric Auger , kvmarm@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/7] arm64/boot: Enable EL2 requirements for FEAT_PMUv3p9 In-Reply-To: References: <20241220072240.1003352-1-anshuman.khandual@arm.com> <20250102160402.GB3990035-robh@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/29.4 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: robh@kernel.org, catalin.marinas@arm.com, anshuman.khandual@arm.com, linux-arm-kernel@lists.infradead.org, will@kernel.org, ryan.roberts@arm.com, mark.rutland@arm.com, oliver.upton@linux.dev, corbet@lwn.net, eric.auger@redhat.com, kvmarm@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250108_031517_131048_B000EF17 X-CRM114-Status: GOOD ( 31.85 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 07 Jan 2025 22:13:47 +0000, Rob Herring wrote: >=20 > On Tue, Jan 7, 2025 at 6:13=E2=80=AFAM Catalin Marinas wrote: > > > > On Thu, Jan 02, 2025 at 10:04:02AM -0600, Rob Herring wrote: > > > On Fri, Dec 20, 2024 at 12:52:33PM +0530, Anshuman Khandual wrote: > > > > This series adds fine grained trap control in EL2 required for FEAT= _PMUv3p9 > > > > registers like PMICNTR_EL0, PMICFILTR_EL0, and PMUACR_EL1 which are= already > > > > being used in the kernel. This is required to prevent their EL1 acc= ess trap > > > > into EL2. > > > > > > > > PMZR_EL0 register trap control i.e HDFGWTR2_EL2.nPMZR_EL0 remains u= nchanged > > > > for now as it does not get accessed in the kernel, and there is no = plan for > > > > its access from user space. > > > > > > > > I have taken the liberty to pick up all the review tags for patches= related > > > > to tools sysreg update from the KVM FGT2 V2 patch series posted ear= lier. > > > > > > > > https://lore.kernel.org/all/20241210055311.780688-1-anshuman.khandu= al@arm.com/ > > > > > > > > Rob had earler mentioned about FEAT_FGT2 based trap control require= ment for > > > > FEAT_PMUv3p9 registers that are currently being used in kernel. The= context > > > > can be found here. > > > > > > > > https://lore.kernel.org/all/20241216234251.GA629562-robh@kernel.org/ > > > > > > > > This series is based on v6.13-rc3 > > > > > > > > Cc: Catalin Marinas > > > > Cc: Will Deacon > > > > Cc: Marc Zyngier > > > > Cc: Ryan Roberts > > > > Cc: Mark Rutland > > > > Cc: Mark Brown > > > > Cc: Rob Herring > > > > Cc: Oliver Upton > > > > Cc: Jonathan Corbet > > > > Cc: Eric Auger > > > > Cc: kvmarm@lists.linux.dev > > > > Cc: linux-doc@vger.kernel.org > > > > Cc: linux-kernel@vger.kernel.org > > > > Cc: linux-arm-kernel@lists.infradead.org > > > > > > > > Anshuman Khandual (7): > > > > arm64/sysreg: Update register fields for ID_AA64MMFR0_EL1 > > > > arm64/sysreg: Add register fields for HDFGRTR2_EL2 > > > > arm64/sysreg: Add register fields for HDFGWTR2_EL2 > > > > arm64/sysreg: Add register fields for HFGITR2_EL2 > > > > arm64/sysreg: Add register fields for HFGRTR2_EL2 > > > > arm64/sysreg: Add register fields for HFGWTR2_EL2 > > > > arm64/boot: Enable EL2 requirements for FEAT_PMUv3p9 > > > > > > In case it is not clear, this series should be applied to 6.13 as the= 2 > > > PMUv3p9 features already landed in 6.13 (per counter EL0 control) and > > > 6.12 (ICNTR). > > > > So is this a fix that needs backporting to 6.12 or 6.13, e.g. fix for > > d8226d8cfbaf ("perf: arm_pmuv3: Add support for Armv9.4 PMU instruction > > counter")? It's pretty late in the cycle to take the series for 6.13. >=20 > Ideally, yes. But given the state of h/w implementations, backporting > it later is probably fine if that is your preference. >=20 > > But does KVM actually expose the feature to EL1 in ID_AA64DFR1_EL1 and > > than traps it at EL2? >=20 > As Marc pointed out KVM only advertises PMUv3.8. Regardless, guest > accesses to these registers are trapped with or without this series. And most probably generates a nice splat in the kernel log, as nobody updated KVM to handle *correctly* PMICNTR_EL0 traps, let alone deal with the FGT2 registers. M. --=20 Without deviation from the norm, progress is not possible.