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[Xen-devel] yanked share problem

  • To: <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "King, Steven R" <steven.r.king@xxxxxxxxx>
  • Date: Tue, 13 Dec 2005 15:05:06 -0800
  • Delivery-date: Tue, 13 Dec 2005 23:06:48 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AcYAOaf8/3N6JjrCTwm36fCQ+maQSw==
  • Thread-topic: yanked share problem

Hi Folks,

Let's imagine we have two domains, DomU_A and DomU_B.  Being DomU's, the
two domains don't trust each other, but still desire to safely setup a
shared memory page.

The scenario is the following:

DomU_A acquires a grant reference and shares a page to DomU_B.
DomU_B gets the grant reference passed from A and maps the shared page.
DomU_A then, due to bug or badness, unshares the page without telling
DomU_B faults on the next access to the mapped but unshared page.

Since one DomU causing a fault in another DomU is unacceptable, the two
domains cannot share memory.  Have I missed something?  I would much
appreciate being set straight on this.


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