linux-kernel - Re: [PATCH v2 1/2] kvm: unmap pages from the iommu when slots are removed

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Date:	Wed, 11 Apr 2012 23:03:57 -0300
From:	Marcelo Tosatti <mtosatti@...hat.com>
To:	Alex Williamson <alex.williamson@...hat.com>
Cc:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org, avi@...hat.com,
	jan.kiszka@...mens.com
Subject: Re: [PATCH v2 1/2] kvm: unmap pages from the iommu when slots are
 removed

On Wed, Apr 11, 2012 at 09:51:49AM -0600, Alex Williamson wrote:
> We've been adding new mappings, but not destroying old mappings.
> This can lead to a page leak as pages are pinned using
> get_user_pages, but only unpinned with put_page if they still
> exist in the memslots list on vm shutdown.  A memslot that is
> destroyed while an iommu domain is enabled for the guest will
> therefore result in an elevated page reference count that is
> never cleared.
> 
> Additionally, without this fix, the iommu is only programmed
> with the first translation for a gpa.  This can result in
> peer-to-peer errors if a mapping is destroyed and replaced by a
> new mapping at the same gpa as the iommu will still be pointing
> to the original, pinned memory address.
> 
> Signed-off-by: Alex Williamson <alex.williamson@...hat.com>

Applied, thanks.

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