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Date:   Wed, 21 Jul 2021 09:22:44 +0100
Message-ID: <87im142i0b.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     Sergey Senozhatsky <senozhatsky@chromium.org>
Cc:     Will Deacon <will@kernel.org>,
        Suleiman Souhlal <suleiman@google.com>,
        Joel Fernandes <joelaf@google.com>,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu,
        linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org
Subject: Re: [PATCHv2 2/4] arm64: add guest pvstate support
In-Reply-To: <YPeA5ReGSwBvWGSa@google.com>
References: <20210709043713.887098-1-senozhatsky@chromium.org>
        <20210709043713.887098-3-senozhatsky@chromium.org>
        <877dhv35ea.wl-maz@kernel.org>
        <YPeA5ReGSwBvWGSa@google.com>
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On Wed, 21 Jul 2021 03:05:25 +0100,
Sergey Senozhatsky <senozhatsky@chromium.org> wrote:
> 
> On (21/07/12 16:42), Marc Zyngier wrote:
> > > 
> > > PV-vcpu-state is a per-CPU struct, which, for the time being,
> > > holds boolean `preempted' vCPU state. During the startup,
> > > given that host supports PV-state, each guest vCPU sends
> > > a pointer to its per-CPU variable to the host as a payload
> > 
> > What is the expected memory type for this memory region? What is its
> > life cycle? Where is it allocated from?
> 
> Guest per-CPU area, which physical addresses is shared with the
> host.

Again: what are the memory types you expect this to be used with? When
will the hypervisor ever stop accessing this? How does it work across
reset?

I'm sorry to be that pressing, but these are the gory details that
actually matter if you want this thing to be maintainable.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.