From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoffer Dall Subject: Re: [PATCH v1 05/16] arm64: Helper for parange to PASize Date: Thu, 8 Feb 2018 12:21:06 +0100 Message-ID: <20180208112106.GO29286@cbox> References: <20180109190414.4017-1-suzuki.poulose@arm.com> <20180109190414.4017-6-suzuki.poulose@arm.com> <20180208110042.GH29286@cbox> <040b00f2-3e83-a475-ae20-5e9358fc580a@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, marc.zyngier@arm.com, linux-kernel@vger.kernel.org, kristina.martsenko@arm.com, peter.maydell@linaro.org, pbonzini@redhat.com, rkrcmar@redhat.com, will.deacon@arm.com, ard.biesheuvel@linaro.org, mark.rutland@arm.com, catalin.marinas@arm.com To: Suzuki K Poulose Return-path: Received: from mail-wm0-f68.google.com ([74.125.82.68]:37647 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752258AbeBHLVJ (ORCPT ); Thu, 8 Feb 2018 06:21:09 -0500 Received: by mail-wm0-f68.google.com with SMTP id v71so9230473wmv.2 for ; Thu, 08 Feb 2018 03:21:09 -0800 (PST) Content-Disposition: inline In-Reply-To: <040b00f2-3e83-a475-ae20-5e9358fc580a@arm.com> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, Feb 08, 2018 at 11:08:18AM +0000, Suzuki K Poulose wrote: > On 08/02/18 11:00, Christoffer Dall wrote: > >On Tue, Jan 09, 2018 at 07:04:00PM +0000, Suzuki K Poulose wrote: > >>Add a helper to convert ID_AA64MMFR0_EL1:PARange to they physical > > *the* > >>size shift. Limit the size to the maximum supported by the kernel. > > > >Is this just a cleanup or are we actually going to need this feature in > >the subsequent patches? That would be nice to motivate in the commit > >letter. > > It is a cleanup, plus we are going to move the user of the code around from > one place to the other. So this makes it a bit easier and cleaner. > On its own I'm not sure it really is a cleanup, so it's good to mention that this is to make some operation easier later on in the commit letter. > > >> > >>Cc: Mark Rutland > >>Cc: Catalin Marinas > >>Cc: Will Deacon > >>Cc: Marc Zyngier > >>Signed-off-by: Suzuki K Poulose > >>--- > >> arch/arm64/include/asm/cpufeature.h | 16 ++++++++++++++++ > >> arch/arm64/kvm/hyp/s2-setup.c | 28 +++++----------------------- > >> 2 files changed, 21 insertions(+), 23 deletions(-) > >> > >>diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h > >>index ac67cfc2585a..0564e14616eb 100644 > >>--- a/arch/arm64/include/asm/cpufeature.h > >>+++ b/arch/arm64/include/asm/cpufeature.h > >>@@ -304,6 +304,22 @@ static inline u64 read_zcr_features(void) > >> return zcr; > >> } > >>+static inline u32 id_aa64mmfr0_parange_to_phys_shift(int parange) > >>+{ > >>+ switch (parange) { > >>+ case 0: return 32; > >>+ case 1: return 36; > >>+ case 2: return 40; > >>+ case 3: return 42; > >>+ case 4: return 44; > >>+ > >>+ default: > > > >What is the case we want to cater for with making parange == 5 the > >default for unrecognized values? > > > >(I have a feeling that default label comes from making the compiler > >happy about potentially uninitialized values once upon a time before a > >lot of refactoring happened here.) > > That is there to make sure we return 48 iff 52bit support (for that matter, > if there is a new limit in the future) is not enabled. > duh, yeah, it's obvious when I look at it again now. > > > >>+ case 5: return 48; > >>+#ifdef CONFIG_ARM64_PA_BITS_52 > >>+ case 6: return 52; > >>+#endif > >>+ } > >>+} > >> #endif /* __ASSEMBLY__ */ > Thanks, -Christoffer