[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 0/4] xen: map foreign pages for shared rings by updating the PTEs directly
On 29/09/11 17:07, Jan Beulich wrote: >>>> On 29.09.11 at 17:53, David Vrabel <david.vrabel@xxxxxxxxxx> wrote: >> [Resend as requested by Konrad.] >> >> This series of patches allows the vmalloc_sync_all() to be removed >> from alloc_vm_area() by getting the hypervisor to update the PTEs (in >> init_mm) directly rather than having the hypervisor look in the >> current page tables to find the PTEs. >> >> Once the hypervisor has updated the PTEs, the normal mechanism of >> syncing the page tables after a fault works as expected. > > Did you actually test that, and namely the case where alloc_vm_area() > would result in a new top level page directory entry to get populated? > > I cannot see how this new entry would propagate into other mm-s, and > hence I cannot see how you can do away with calling vmalloc_sync_all() > just by changing how leaf page table entries get populated. I don't think this new behaviour of alloc_vm_area() is any different from how a regular vmalloc() works. vmalloc_fault() copies the page table entries from init_mm into the current MM (on 32-bit it calls vmalloc_sync_one() which makes it obviously correct I think). David >> This mechanism doesn't currently work on the ia64 port as that does >> not support the GNTMAP_contains_pte flag. >> >> David _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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