linux-kernel - Re: [PATCH] arm64: trans_pgd: mark PTEs entries as valid to avoid dead kexec()

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Message-Id: <172546382382.2661386.11693595426476594538.b4-ty@kernel.org>
Date: Wed,  4 Sep 2024 17:12:33 +0100
From: Will Deacon <will@...nel.org>
To: Fares Mehanna <faresx@...zon.de>
Cc: catalin.marinas@....com,
	kernel-team@...roid.com,
	Will Deacon <will@...nel.org>,
	nh-open-source@...zon.com,
	Jan H . Schönherr <jschoenh@...zon.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ryan Roberts <ryan.roberts@....com>,
	Mark Rutland <mark.rutland@....com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: trans_pgd: mark PTEs entries as valid to avoid dead kexec()

On Mon, 02 Sep 2024 16:33:08 +0000, Fares Mehanna wrote:
> The reasons for PTEs in the kernel direct map to be marked invalid are not
> limited to kfence / debug pagealloc machinery. In particular,
> memfd_secret() also steals pages with set_direct_map_invalid_noflush().
> 
> When building the transitional page tables for kexec from the current
> kernel's page tables, those pages need to become regular writable pages,
> otherwise, if the relocation places kexec segments over such pages, a fault
> will occur during kexec, leading to host going dark during kexec.
> 
> [...]

Applied to arm64 (for-next/mm), thanks!

[1/1] arm64: trans_pgd: mark PTEs entries as valid to avoid dead kexec()
      https://git.kernel.org/arm64/c/7eced90b202d

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev