From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A6AA61CF8C for ; Mon, 13 Nov 2023 11:55:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=none Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4A1DBFEC; Mon, 13 Nov 2023 03:55:50 -0800 (PST) Received: from [10.57.73.13] (unknown [10.57.73.13]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DA6E63F6C4; Mon, 13 Nov 2023 03:55:02 -0800 (PST) Message-ID: <3800df70-73f2-44b7-a6ed-15ec0bd63f5f@arm.com> Date: Mon, 13 Nov 2023 11:55:01 +0000 Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v1 0/3] Update tlb invalidation routines for FEAT_LPA2 Content-Language: en-GB To: Ard Biesheuvel , Ard Biesheuvel , Will Deacon , Catalin Marinas , Marc Zyngier , Oliver Upton , Mark Rutland , Anshuman Khandual , Kees Cook , Joey Gouly , Suzuki K Poulose , James Morse , Zenghui Yu Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev References: <20231027115634.1432154-1-ryan.roberts@arm.com> From: Ryan Roberts In-Reply-To: <20231027115634.1432154-1-ryan.roberts@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 27/10/2023 12:56, Ryan Roberts wrote: > Hi All, > > As raised yesterday against Ard's LPA2 series [1], we need to address the TLBI > changes to properly support LPA2 before Ard's changes get merged. So far those > changes have been part of my KVM LPA2 series [2]. So this is an attempt to split > the TLBI changes to make them independent. The idea is that this series would go > in first, then Ard's and the rest of my series can race eachother and it doesn't > really matter who wins. > > I've attempted to address all of Marc's feedback against the versions of these > patches posted at [2], including adding benchmark data (see patch 1). Although > if people are still nervous that this could regress non-lpa2 performance in some > cases, I could rework so that there are lpa2 and non-lpa2 variants of > __flush_tlb_range_op(), and the correct version is chosen at the higher level > (based on lpa2_is_enabled() / kvm_lpa2_is_enabled()). > > It turns out that we won't be able to key LPA2 usage off the same static key for > both the kernel and kvm usage because the kernel usage additionally depends on > CONFIG_ARM64_LPA2 being enabled. So I've introduced 2 stub functions > (lpa2_is_enabled() and kvm_lpa2_is_enabled()) to advertise it. Ard already > defines and implements lpa2_is_enabled() in his series, so there will be a minor > conflict to resolve there. I plan to define kvm_lpa2_is_enabled() to be the > static key for kvm in my series. Marc, would you be happy with this approach? > > Anyway, I wanted to put this out there as an RFC. If we are happy with it, then > I'll re-post on 6.7-rc1. Marc, All, I polite bump; I never heard back on this. I'm planning to post my LPA2/KVM series on top of v6.7-rc1 in the next day or 2. By default, these 3 patches will be the first 3 of the series. But if you have an issue with the approach it would be good to work out an alternative plan to avoid wasting effort preparing the series. Thanks, Ryan > > [1] https://lore.kernel.org/linux-arm-kernel/5651bb31-9ef6-4dfc-b146-64606279bbf7@arm.com/ > [2] https://lore.kernel.org/kvmarm/20231009185008.3803879-1-ryan.roberts@arm.com/ > > Thanks, > Ryan > > Ryan Roberts (3): > arm64/mm: Modify range-based tlbi to decrement scale > arm64/mm: Add lpa2_is_enabled() kvm_lpa2_is_enabled() stubs > arm64/mm: Update tlb invalidation routines for FEAT_LPA2 > > arch/arm64/include/asm/kvm_mmu.h | 3 + > arch/arm64/include/asm/pgtable-prot.h | 2 + > arch/arm64/include/asm/tlb.h | 15 ++-- > arch/arm64/include/asm/tlbflush.h | 100 ++++++++++++++++---------- > 4 files changed, 78 insertions(+), 42 deletions(-) > > -- > 2.25.1 >