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Date: Thu, 14 May 2015 15:03:18 +0200
From: Andrew Jones <drjones@redhat.com>
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Subject: Re: [Qemu-devel] [RFC/RFT PATCH v2 0/3] KVM: Introduce
	KVM_MEM_UNCACHED
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>, Marc Zyngier <marc.zyngier@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, QEMU Developers <qemu-devel@nongnu.org>, Alexander Graf <agraf@suse.de>, Paolo Bonzini <pbonzini@redhat.com>, Laszlo Ersek <lersek@redhat.com>, "kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>, Christoffer Dall <christoffer.dall@linaro.org>

On Thu, May 14, 2015 at 11:37:46AM +0100, Peter Maydell wrote:
> On 14 May 2015 at 11:31, Andrew Jones <drjones@redhat.com> wrote:
> > Forgot to (4): switch from setting userspace's mapping to
> > device memory to normal, non-cacheable. Using device memory
> > caused a problem that Alex Graf found, and Peter Maydell suggested
> > using normal, non-cacheable instead.
> 
> Did you check that non-cacheable is definitely the correct
> kind of Normal memory attribute we want? (ie not write-through).

I was concerned that write-through wouldn't be sufficient. If the
guest writes to its non-cached memory, and QEMU needs to see what
it wrote, then won't write-through fail to work? Unless we some
how invalidate the cache first?

drew