From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5F86BB640; Mon, 11 Aug 2025 17:47:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754934428; cv=none; b=OEDMsPcBd6+ohltspSPPnlJQk2Zqk3BnRKYpFWXImLMp0WFTSNbTBDuPjK2qT6JaPBgLT7vFv/vI++5hqc9hDi34pY1+plAyL3GHDGIZYqdQurWnmovov1nZbZfoNJsW0M94T7fqTBvA8DRtpjOKsQrgxq5dFjPcD0Nfm0c+UNE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754934428; c=relaxed/simple; bh=mKkMaxD4qpSG42cXfEv3ipOX0l9wTH41ysdWD1UmrT0=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=VTWm4EUOq/Y+BPliaxDp+Aay7hCGKRGnHtEBACMCC2NFpEGYp8yOWpoL8nY6NTRFb4/Jnh9+n1AHHxr58kPVstXGwwDBJ50w7QL1I8M55+/I3LY88r84AZMZQsX2XNzjiP06Zx9vuqyRvIjmbZJCJWsCA+VIkg9YtthCiaeW144= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VQUhIEGP; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VQUhIEGP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C0E84C4CEED; Mon, 11 Aug 2025 17:47:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754934427; bh=mKkMaxD4qpSG42cXfEv3ipOX0l9wTH41ysdWD1UmrT0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=VQUhIEGPNQISsLZcnMINwUCYKwurxMVFcnnTSSVsMcchwocP/tXl7XzBCvbHJye/L 78fWe94P8TB1QeNbZxSiY4e4e/EsLD2sCTZRSYyzvoB2quOJO9Zn2QW41rK+SOrkVB 1DGsBklzX/0bkNlZvfay1W6Jxs9GQhTtqLw0tqGJd45coWAQV5KpCdhwROCIpy9SqP iVkKAyUy2ehBGWf7HRfh8XKry1uwTNJX9JYE7bQSSYkvh+5J9yUM+KZSwWXoilId38 NmnTiYuAImqp9HLINsn7xz+6tKgCx7SeXQMepyaW8zDRhD3jnWZJtrkKjamUxzoton WjmlsY78uNvOg== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1ulWbh-006Lr3-KO; Mon, 11 Aug 2025 18:46:50 +0100 Date: Mon, 11 Aug 2025 18:46:48 +0100 Message-ID: <86sehx92ev.wl-maz@kernel.org> From: Marc Zyngier To: Yeoreum Yun Cc: catalin.marinas@arm.com, will@kernel.org, broonie@kernel.org, oliver.upton@linux.dev, anshuman.khandual@arm.com, robh@kernel.org, james.morse@arm.com, mark.rutland@arm.com, joey.gouly@arm.com, ry111@xry111.site, Dave.Martin@arm.com, ahmed.genidi@arm.com, kevin.brodsky@arm.com, scott@os.amperecomputing.com, mbenes@suse.cz, james.clark@linaro.org, frederic@kernel.org, rafael@kernel.org, pavel@kernel.org, ryan.roberts@arm.com, suzuki.poulose@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, kvmarm@lists.linux.dev Subject: Re: [PATCH v2 1/6] arm64: make SCTLR2_EL1 accessible In-Reply-To: <20250811163340.1561893-2-yeoreum.yun@arm.com> References: <20250811163340.1561893-1-yeoreum.yun@arm.com> <20250811163340.1561893-2-yeoreum.yun@arm.com> 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/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: yeoreum.yun@arm.com, catalin.marinas@arm.com, will@kernel.org, broonie@kernel.org, oliver.upton@linux.dev, anshuman.khandual@arm.com, robh@kernel.org, james.morse@arm.com, mark.rutland@arm.com, joey.gouly@arm.com, ry111@xry111.site, Dave.Martin@arm.com, ahmed.genidi@arm.com, kevin.brodsky@arm.com, scott@os.amperecomputing.com, mbenes@suse.cz, james.clark@linaro.org, frederic@kernel.org, rafael@kernel.org, pavel@kernel.org, ryan.roberts@arm.com, suzuki.poulose@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, kvmarm@lists.linux.dev X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Mon, 11 Aug 2025 17:33:35 +0100, Yeoreum Yun wrote: > > make SCTLR2_EL1 accssible to initilise it. nit: "accessible", "initialise". This could deserve a slightly less terse message, so that someone who is not very much versed into the boring details of the architecture can make sense of this patch. Because, frankly, if you can access HCRX_EL2, why can't you access SCTLR2_EL1? You know why, I know why, but hardly anyone else does. I'd suggest something along the lines of: "When the kernel runs at EL1, and yet is booted at EL2, HCRX_EL2.SCTLR2En must be set to avoid trapping SCTLR2_EL1 accesses from EL1 to EL2. Ensure this bit is set at the point of initialising EL2." which at least explains why we're doing this. > > Signed-off-by: Yeoreum Yun > --- > arch/arm64/include/asm/el2_setup.h | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h > index 46033027510c..d755b4d46d77 100644 > --- a/arch/arm64/include/asm/el2_setup.h > +++ b/arch/arm64/include/asm/el2_setup.h > @@ -57,9 +57,15 @@ > /* Enable GCS if supported */ > mrs_s x1, SYS_ID_AA64PFR1_EL1 > ubfx x1, x1, #ID_AA64PFR1_EL1_GCS_SHIFT, #4 > - cbz x1, .Lset_hcrx_\@ > + cbz x1, .Lskip_hcrx_GCSEn_\@ > orr x0, x0, #HCRX_EL2_GCSEn > > +.Lskip_hcrx_GCSEn_\@: > + mrs_s x1, SYS_ID_AA64MMFR3_EL1 > + ubfx x1, x1, #ID_AA64MMFR3_EL1_SCTLRX_SHIFT, #4 > + cbz x1, .Lset_hcrx_\@ > + orr x0, x0, HCRX_EL2_SCTLR2En > + > .Lset_hcrx_\@: > msr_s SYS_HCRX_EL2, x0 > .Lskip_hcrx_\@: With that fixed, Reviewed-by: Marc Zyngier M. -- Without deviation from the norm, progress is not possible.