Messages in this thread | | | Date | Tue, 16 Jun 2015 10:19:43 -0400 | From | Boris Ostrovsky <> | Subject | Re: [PATCH 07/12] x86/virt/guest/xen: Remove use of pgd_list from the Xen guest code |
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On 06/16/2015 10:15 AM, David Vrabel wrote: > On 15/06/15 21:35, Ingo Molnar wrote: >> * David Vrabel <david.vrabel@citrix.com> wrote: >> >>> On 15/06/15 10:05, Ian Campbell wrote: >>>> On Sat, 2015-06-13 at 11:49 +0200, Ingo Molnar wrote: >>>>> xen_mm_pin_all()/unpin_all() are used to implement full guest instance >>>>> suspend/restore. It's a stop-all method that needs to iterate through all >>>>> allocated pgds in the system to fix them up for Xen's use. >>>>> >>>>> This code uses pgd_list, probably because it was an easy interface. >>>>> >>>>> But we want to remove the pgd_list, so convert the code over to walk all >>>>> tasks in the system. This is an equivalent method. >>> It is not equivalent because pgd_alloc() now populates entries in pgds that are >>> not visible to xen_mm_pin_all() (note how the original code adds the pgd to the >>> pgd_list in pgd_ctor() before calling pgd_prepopulate_pmd()). These newly >>> allocated page tables won't be correctly converted on suspend/resume and the new >>> process will die after resume. >> So how should the Xen logic be fixed for the new scheme? I can't say I can see >> through the paravirt complexity here. > Actually, since we freeze_processes() before trying to pin page tables, > I think it should be ok as-is. > > I'll put the patch through some tests.
Actually, I just ran this through a couple of boot/suspend/resume tests and didn't see any issues (with the one fix I mentioned to Ingo earlier). On unstable Xen only.
-boris
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