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From: m.smarduch@samsung.com (Mario Smarduch)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] ARM: kvm: define PAGE_S2_DEVICE as read-only by default
Date: Wed, 17 Sep 2014 12:19:50 -0700	[thread overview]
Message-ID: <5419DED6.6050307@samsung.com> (raw)
In-Reply-To: <CAKv+Gu-MAkzFtrFk19mYB=jQyLsFLY+k3Ly=eZQ=3hWSALLRPw@mail.gmail.com>

On 09/14/2014 03:57 PM, Ard Biesheuvel wrote:

> 
> Never mind. I read the whole thread this time.
> 
> So, in summary, there is a concern that a malicious guest may request
> a cachable mapping for a device range, in an attempt to manipulate the
> VGIC or other device memory of another VM.
> I think that concern only applies to writable mappings, so perhaps we
> should just change
> 
> if (kvm_is_mmio_pfn(pfn))
> 
> to
> 
> if (kvm_is_mmio_pfn(pfn) && writable)
Hi Ard,

What if the device passed through is read-only like maybe IPMI
sensors.

> 
> and be done with it (which is coincidentally the very first naive fix
> I suggested for the issue i was seeing)
> That way, we never map read-only MMIO regions writable, and rely on
> the MT_DEVICE trumps MT_NORMAL rule to ensure the guest reads to those
> regions are uncached.
> (Wouldn't hurt to add a comment to explain it, I suppose)
> 

      parent reply	other threads:[~2014-09-17 19:19 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-13 10:17 [PATCH 1/2] ARM: kvm: define PAGE_S2_DEVICE as read-only by default Ard Biesheuvel
2014-09-13 10:17 ` [PATCH 2/2] arm64: " Ard Biesheuvel
2014-09-13 10:41 ` [PATCH 1/2] ARM: " Marc Zyngier
2014-09-13 11:15   ` Ard Biesheuvel
2014-09-13 17:06     ` Christoffer Dall
2014-09-14  4:49       ` Ard Biesheuvel
2014-09-14  9:09         ` Marc Zyngier
2014-09-14  9:43           ` Ard Biesheuvel
2014-09-14 22:57             ` Ard Biesheuvel
2014-09-15  3:37               ` Peter Maydell
2014-09-15 19:41               ` Mario Smarduch
2014-09-15 19:45                 ` Peter Maydell
2014-09-17 19:19               ` Mario Smarduch [this message]

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