linux-kernel - Re: [PATCH v3 07/32] KVM: arm64: Introduce a BSS section for use at Hyp

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Message-ID: <20210304140935.GD21229@willie-the-truck>
Date:   Thu, 4 Mar 2021 14:09:36 +0000
From:   Will Deacon <will@...nel.org>
To:     Quentin Perret <qperret@...gle.com>
Cc:     catalin.marinas@....com, maz@...nel.org, james.morse@....com,
        julien.thierry.kdev@...il.com, suzuki.poulose@....com,
        android-kvm@...gle.com, linux-kernel@...r.kernel.org,
        kernel-team@...roid.com, kvmarm@...ts.cs.columbia.edu,
        linux-arm-kernel@...ts.infradead.org, tabba@...gle.com,
        mark.rutland@....com, dbrazdil@...gle.com, mate.toth-pal@....com,
        seanjc@...gle.com, robh+dt@...nel.org
Subject: Re: [PATCH v3 07/32] KVM: arm64: Introduce a BSS section for use at
 Hyp

On Tue, Mar 02, 2021 at 02:59:37PM +0000, Quentin Perret wrote:
> Currently, the hyp code cannot make full use of a bss, as the kernel
> section is mapped read-only.
> 
> While this mapping could simply be changed to read-write, it would
> intermingle even more the hyp and kernel state than they currently are.
> Instead, introduce a __hyp_bss section, that uses reserved pages, and
> create the appropriate RW hyp mappings during KVM init.
> 
> Signed-off-by: Quentin Perret <qperret@...gle.com>
> ---
>  arch/arm64/include/asm/sections.h |  1 +
>  arch/arm64/kernel/vmlinux.lds.S   | 52 ++++++++++++++++++++-----------
>  arch/arm64/kvm/arm.c              | 14 ++++++++-
>  arch/arm64/kvm/hyp/nvhe/hyp.lds.S |  1 +
>  4 files changed, 49 insertions(+), 19 deletions(-)

Acked-by: Will Deacon <will@...nel.org>

Will