From: Jon Masters <jcm@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>,
Mario Smarduch <m.smarduch@samsung.com>
Cc: Laszlo Ersek <lersek@redhat.com>, kvm-devel <kvm@vger.kernel.org>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Paolo Bonzini <pbonzini@redhat.com>,
"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>
Subject: Re: [PATCH 3/3] arm, arm64: KVM: handle potential incoherency of readonly memslots
Date: Thu, 20 Nov 2014 14:49:54 -0500 [thread overview]
Message-ID: <546E45E2.1030002@redhat.com> (raw)
In-Reply-To: <CAFEAcA-nSTY_k1gvJ8_y9P6wP2MmOgJzobK-rXp1W6XtrPAMbw@mail.gmail.com>
On 11/20/2014 01:40 PM, Peter Maydell wrote:
> On 20 November 2014 18:35, Mario Smarduch <m.smarduch@samsung.com> wrote:
>> I think beyond consistency, there should be no double mappings with
>> conflicting attributes at any time or CPU state is undefined.
>
> The situation is not so bleak as this. See section B2.9 "Mismatched
> memory attributes" in the ARMv8 ARM ARM (DDI0487A.d), which lays
> out in some detail what the results of mismatched attributes are
> (generally, you lose ordering or coherency guarantees you might
> have hoped to have). They're not pretty, but it's not as bad
> as completely UNPREDICTABLE behaviour.
Quick side note that I did raise exactly this issue with the ARM
Architecture team several years ago (that of missmatched memory
attributes between a guest and hypervisor) and it is a known concern.
I'm personally concerned about a couple of things that I won't go into
here but will followup on what the longer term plan might be.
Jon.
next prev parent reply other threads:[~2014-11-20 19:50 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-17 14:58 [PATCH 1/3] kvm: add a memslot flag for incoherent memory regions Ard Biesheuvel
2014-11-17 14:58 ` [PATCH 2/3] arm, arm64: KVM: allow forced dcache flush on page faults Ard Biesheuvel
2014-11-17 14:58 ` [PATCH 3/3] arm, arm64: KVM: handle potential incoherency of readonly memslots Ard Biesheuvel
2014-11-17 15:29 ` Paolo Bonzini
2014-11-17 15:39 ` Marc Zyngier
2014-11-17 16:03 ` Paolo Bonzini
2014-11-17 15:49 ` Laszlo Ersek
2014-11-19 23:32 ` Mario Smarduch
2014-11-20 8:08 ` Laszlo Ersek
2014-11-20 18:35 ` Mario Smarduch
2014-11-20 18:40 ` Peter Maydell
2014-11-20 19:15 ` Mario Smarduch
2014-11-20 19:49 ` Jon Masters [this message]
2014-11-20 20:10 ` Peter Maydell
2014-11-20 21:13 ` Laszlo Ersek
2014-11-20 21:59 ` Peter Maydell
2014-11-21 11:19 ` Christoffer Dall
2014-11-22 1:50 ` Mario Smarduch
2014-11-22 10:18 ` Christoffer Dall
2014-11-22 10:26 ` Laszlo Ersek
2014-11-22 12:27 ` Peter Maydell
2014-11-19 8:51 ` Ard Biesheuvel
2014-11-19 11:02 ` Paolo Bonzini
2014-11-19 11:03 ` Paolo Bonzini
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