[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xen/balloon: don't alloc page while non-preemptible
On Wed, 25 Sep 2013, David Vrabel wrote: > On 25/09/13 14:26, Stefano Stabellini wrote: > > On Thu, 19 Sep 2013, David Vrabel wrote: > >> > >> - put_balloon_scratch_page(); > >> + /* Ensure that ballooned highmem pages don't have kmaps. */ > >> + kmap_flush_unused(); > >> + flush_tlb_all(); > > > > The change with possible side effects in this patch is that > > kmap_flush_unused and flush_tlb_all are now called after setting the p2m > > and after calling balloon_append instead of before. > > > > However they are still called before the XENMEM_decrease_reservation > > hypercall, so I think it's OK. > > Yes, the requirement is that the kmap cache is flushed before releasing > the frame to Xen (in case it contains a kmap for a frame we're about to > release). > > I also wonder if the flush_tlb_all() is even necessary. Surely Xen has > all the appropriate TLB flushes in the decrease_reservation hypercall. > It can't possibly rely on the guest doing the right thing. That would only be the case for PV guests, but yes, Xen has certainly a flush. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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