Messages in this thread | | | Date | Fri, 29 May 2020 10:41:44 +0100 | From | Marc Zyngier <> | Subject | Re: [PATCH RFCv2 9/9] arm64: Support async page fault |
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On 2020-05-29 00:02, Gavin Shan wrote: > Hi Paolo, > > On 5/28/20 8:48 PM, Paolo Bonzini wrote: >> On 28/05/20 08:14, Gavin Shan wrote: >>>> - for x86 we're also thinking of initiating the page fault from the >>>> exception handler, rather than doing so from the hypervisor before >>>> injecting the exception. If ARM leads the way here, we would do our >>>> best to share code when x86 does the same. >>> >>> Sorry, Paolo, I don't follow your idea here. Could you please provide >>> more details? >> >> The idea is to inject stage2 page faults into the guest even before >> the >> host starts populates the page. The guest then invokes a hypercall, >> telling the host to populate the page table and inject the 'page >> ready' >> event (interrupt) when it's done. >> >> For x86 the advantage is that the processor can take care of raising >> the >> stage2 page fault in the guest, so it's faster. >> > I think there might be too much overhead if the page can be populated > quickly by host. For example, it's fast to populate the pages if swapin > isn't involved. > > If I'm correct enough, it seems arm64 doesn't have similar mechanism, > routing stage2 page fault to guest.
Indeed, this isn't a thing on arm64. Exception caused by a S2 fault are always routed to EL2.
M. -- Jazz is not dead. It just smells funny...
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