[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 07/12] x86/virt/guest/xen: Remove use of pgd_list from the Xen guest code
On 06/16/2015 10:15 AM, David Vrabel wrote: On 15/06/15 21:35, Ingo Molnar wrote:* David Vrabel <david.vrabel@xxxxxxxxxx> 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 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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