[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 2/2] Xen/mem_event: Prevent underflow of vcpu pause counts
On Thu, Jul 17, 2014 at 9:10 AM, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote: Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> Not so sure about this one, see below. --- This is a problem. It relies on a vcpu being able to cause a single mem event during a vmexit. I don't think that can be guaranteed. While I can't pinpoint the exact conversation from years ago, it is not hard to imagine scenarios in which an mmio emulation can touch multiple pages. So I don't think we can BUG_ON at all.Â
+ Â Âvcpu_pause_nosync(v); And now that we consider more than one mem event piling up to pause a vcpu, this has to become an atomic counter, which unpauses on zero, and takes care of underflow.
This is great and thanks for catching these things. Andres +    Âvcpu_unpause(v); _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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