linux-kernel - Re: [PATCH 0/2] Fixes for pKVM NP-guest support

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Message-ID: <Z6ZJ4LDSOG6Lr2Ba@linux.dev>
Date: Fri, 7 Feb 2025 09:58:56 -0800
From: Oliver Upton <oliver.upton@...ux.dev>
To: Quentin Perret <qperret@...gle.com>
Cc: Marc Zyngier <maz@...nel.org>, Joey Gouly <joey.gouly@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>, Fuad Tabba <tabba@...gle.com>,
	Vincent Donnefort <vdonnefort@...gle.com>,
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] Fixes for pKVM NP-guest support

On Fri, Feb 07, 2025 at 02:54:36PM +0000, Quentin Perret wrote:
> Hi all,
> 
> Here are two patches to deal with a race between the handling of
> permission faults and MMU notifiers with pKVM that I found by
> inspection. Specifically, pKVM gets thoroughly confused when it doesn't
> find a page mapped in its relax_perm path, while standard KVM deals
> with that trivially thanks to the -EAGAIN special case in
> user_mem_abort(). The second patch addresses the problem by simplifying
> the implementation of multiple pKVM hypercalls, which also has the nice
> side effect of improving locking by not taking the global host stage-2
> lock as much.
> 
> Patches based on 6.14-rc1, tested in qemu on on Google Pixel 6.

Looks reasonable to me, the locking improvements are certainly an added
bonus.

Reviewed-by: Oliver Upton <oliver.upton@...ux.dev>

-- 
Thanks,
Oliver