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Date:   Tue, 8 Dec 2020 09:40:27 +0000
From:   Will Deacon <will@kernel.org>
To:     Quentin Perret <qperret@google.com>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Marc Zyngier <maz@kernel.org>,
        James Morse <james.morse@arm.com>,
        Julien Thierry <julien.thierry.kdev@gmail.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        "moderated list:ARM64 PORT (AARCH64 ARCHITECTURE)" 
        <linux-arm-kernel@lists.infradead.org>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64)" 
        <kvmarm@lists.cs.columbia.edu>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE" 
        <devicetree@vger.kernel.org>, kernel-team@android.com,
        android-kvm@google.com
Subject: Re: [RFC PATCH 16/27] KVM: arm64: Prepare Hyp memory protection
Message-ID: <20201208094026.GA5562@willie-the-truck>
References: <20201117181607.1761516-1-qperret@google.com>
 <20201117181607.1761516-17-qperret@google.com>
 <20201207134052.GA4563@willie-the-truck>
 <X844CBNCTL4XT3iq@google.com>
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On Mon, Dec 07, 2020 at 02:11:20PM +0000, Quentin Perret wrote:
> On Monday 07 Dec 2020 at 13:40:52 (+0000), Will Deacon wrote:
> > Why not use the RESERVEDMEM_OF_DECLARE() interface for the hypervisor
> > memory? That way, the hypervisor memory can either be statically partitioned
> > as a carveout or allocated dynamically for us -- we wouldn't need to care.
> 
> Yup, I did consider that, but the actual amount of memory we need to
> reserve for the hypervisor depends on things such as the size of struct
> hyp_page, which depends on the kernel you're running (that is, it might
> change over time). So, that really felt like something the kernel should
> be doing, to keep the DT backward compatible, ... Or did you have
> something more elaborate in mind?

No, that's fair. Just wanted to make sure we had a good reason not to use
the existing memory reservation code.

Will