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[Xen-devel] RE: [PATCH][discuss] evtchn race condition

  • To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>
  • From: "Woller, Thomas" <thomas.woller@xxxxxxx>
  • Date: Mon, 27 Feb 2006 17:05:16 -0600
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Mon, 27 Feb 2006 23:06:04 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AcY5+1goMniAdwr9TkykY5OfU61KGwB9kjtQ
  • Thread-topic: [PATCH][discuss] evtchn race condition

Keir Fraser wrote:
> It looks as though the patch probably disables blocking on
> halt entirely, since you unconditionally set
> evtchn_pending_sel and evtchn_upcall_pedning on exit from
> hvm_wait_io. This then causes you to immediately exit from
> hvm_safe_block (since the pending_sel and upcall_pending will
> always both be != 0). Replacing your patch with one that
> simply removes the call to hvm_safe_block() from
> svm_vmexit_do_hlt() would I expect have the same effect (may be worth
> confirming?). 
Yes - you are correct. 
removing hvm_safe_block() from the hlt function alleviates the issue

Attached is simple patch to remove hvm_safe_block() as a tmp solution.

Since this is only an SVM file modification, should not affect VT code

Can you apply until final solution is found?
Applies cleanly to 8991.


Signed-off-by: Tom Woller <thomas.woller@xxxxxxx>

Attachment: svm_tmp_evtchn_fix.patch
Description: svm_tmp_evtchn_fix.patch

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