Re: [RFC PATCH 0/7] arm64: Enable LPA2 support for 16k pages

From: Anshuman Khandual <anshuman.khandual@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
	Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Kees Cook <keescook@chromium.org>,
	Mark Brown <broonie@kernel.org>,
	Richard Henderson <richard.henderson@linaro.org>
Subject: Re: [RFC PATCH 0/7] arm64: Enable LPA2 support for 16k pages
Date: Fri, 18 Nov 2022 16:48:03 +0530	[thread overview]
Message-ID: <e14d0820-6310-cc03-acd2-3cc3acfb3759@arm.com> (raw)
In-Reply-To: <Y3dgl3Q9x84NUlwM@arm.com>

On 11/18/22 16:08, Catalin Marinas wrote:
> Hi Ard,
> 
> On Thu, Nov 17, 2022 at 02:24:16PM +0100, Ard Biesheuvel wrote:
>> Enable support for LPA2 when running with 16k pages. Unlike with 4k
>> pages, this does not require adding support for 5 level paging, but
>> beyond that, there is no fundamental difference between LPA2 support on
>> 4k or 16k pages.
> We have some patches already from Anshuman, targeting both 4K and 16K
> pages:
> 
> https://lore.kernel.org/r/1632998116-11552-1-git-send-email-anshuman.khandual@arm.com
> 
> I don't think they've been rebased on top of 6.1-rcX though. Could you
> please liaise with Anshuman and agree on a way forward? I'd rather only
> review a single series if they do the same thing. I have a preference
> for a more complete solution (4K and 16K) rather than just 16K pages. I
> think we can even ignore some corner cases like 39-bit VA (if anyone is
> asking, we could do it later but it doesn't seem realistic).
> 
> And a question for Anshuman: do you plan to refresh your series?
This contains above series rebased on v6.1-rc1, but without an working idmap
though, which prevents booting the kernel loaded beyond 48 bits PA.

https://gitlab.arm.com/linux-arm/linux-anshuman/-/commits/lpa2/rfc/v2/

But in the local tree, fixed 'init_idmap_pg_dir' to boot the kernel beyond 48
bit physical address for [4K|48VA|52PA], but still working towards getting the
runtime 'idmap_pg_dir' right, although the kernel still boots if 'init_pg_dir'
is used instead in all such places.

Regardless, I will post the series early next week for all of us to sync up.

- Anshuman

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