linux-kernel - Re: [PATCH v5 13/19] arm64: Make the PHYS_MASK

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Message-ID: <ZsxZgzXGbwqxrk6g@arm.com>
Date: Mon, 26 Aug 2024 13:31:31 +0300
From: Catalin Marinas <catalin.marinas@....com>
To: Steven Price <steven.price@....com>
Cc: kvm@...r.kernel.org, kvmarm@...ts.linux.dev,
	Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>,
	James Morse <james.morse@....com>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Joey Gouly <joey.gouly@....com>,
	Alexandru Elisei <alexandru.elisei@....com>,
	Christoffer Dall <christoffer.dall@....com>,
	Fuad Tabba <tabba@...gle.com>, linux-coco@...ts.linux.dev,
	Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>,
	Gavin Shan <gshan@...hat.com>,
	Shanker Donthineni <sdonthineni@...dia.com>,
	Alper Gun <alpergun@...gle.com>
Subject: Re: [PATCH v5 13/19] arm64: Make the PHYS_MASK_SHIFT dynamic

On Mon, Aug 19, 2024 at 02:19:18PM +0100, Steven Price wrote:
> Make the PHYS_MASK_SHIFT dynamic for Realms. This is only is required
> for masking the PFN from a pte entry.

Unless my grep failed, pte_pfn() hasn't used PHYS_MASK for many years,
since commit 75387b92635e ("arm64: handle 52-bit physical addresses in
page table entries").

Can you check what pte_pfn() returns on a shared page?

Unless we need this macro for other things, I'm more tempted to clear
the bit in __pte_to_phys().

-- 
Catalin