Messages in this thread | | | Subject | Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB flush | From | Juergen Gross <> | Date | Fri, 11 Aug 2017 15:07:29 +0200 |
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On 11/08/17 14:54, Peter Zijlstra wrote: > On Fri, Aug 11, 2017 at 02:46:41PM +0200, Juergen Gross wrote: >> Aah, okay. Now I understand the problem. The TLB isn't the issue but the >> IPI is serving two purposes here: TLB flushing (which is allowed to >> happen at any time) and serialization regarding access to critical pages >> (which seems to be broken in the Xen case as you suggest). > > Indeed, and now hyper-v as well.
Is it possible to distinguish between non-critical calls of flush_tlb_others() (which should be the majority IMHO) and critical ones regarding above problem? I guess the only problem is the case when a page table can be freed because its last valid entry is gone, right?
We might want to add a serialization flag to indicate flushing _and_ serialization via IPI should be performed.
Juergen
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