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

["Woller, Thomas" <thomas.woller@xxxxxxx>]

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
also.

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
path.

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

Tom

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

Attachment: svm_tmp_evtchn_fix.patch
Description: svm_tmp_evtchn_fix.patch

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