Messages in this thread | | | From | Vitaly Kuznetsov <> | Subject | Re: [PATCH RFC 0/4] xen/pvhvm: fix shared_info and pirq issues with kexec | Date | Fri, 01 Aug 2014 14:21:20 +0200 |
| |
David Vrabel <david.vrabel@citrix.com> writes:
> On 15/07/14 14:40, Vitaly Kuznetsov wrote: >> With this patch series I'm trying to address several issues with kexec on pvhvm: >> - shared_info issue (1st patch, just sending Olaf's work with Konrad's fix) >> - create specific pvhvm shutdown handler for kexec (2nd patch) >> - GSI PIRQ issue (3rd patch, I'm pretty confident that it does the right thing) >> - MSI PIRQ issue (4th patch, and I'm not sure it doesn't break anything -> RFC) >> >> This patch series can be tested on single vCPU guest. We still have SMP issues with >> pvhvm guests and kexec which require additional fixes. > > In addition to the fixes for multi-VCPU guests, what else remains? >
I'm aware of grants and ballooned out pages.
> What's the plan for handling granted pages? >
(if I got the design right) we have two issues:
1) Pages we grant access to other domains. We have the list so we can try doing gnttab_end_foreign_access for all unmapped grants but there is nothing we can do with mapped ones from guest. We can either assume that all such usages are short-term and try waiting for them to finish or we need to do something like force-unmap from hypervisor side.
2) Pages we mapped from other domains. There is no easy way to collect all grant handles from different places in kernel atm so I can see two possible solutions: - we keep track of all handles with new kernel structure in guest and unmap them all on kexec/kdump. - we introduce new GNTTABOP_reset which does something similar to gnttab_release_mappings().
There is nothing we need to do with transferred grants (and I don't see transfer usages in kernel).
Please correct me if I'm wrong.
> I don't think we want to accept a partial solution unless the known > non-working configurations fail fast on kexec load.
*I think* we can leave ballooned out pages out of scope for now.
Thanks,
> > David
-- Vitaly
| |