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Re: [Xen-devel] [PATCH 8/8] xen/pvh: Enable CPU hotplug

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On 10/14/2016 03:01 PM, Boris Ostrovsky wrote:
> On 10/14/2016 02:41 PM, Andrew Cooper wrote:
>> On 14/10/16 19:05, Boris Ostrovsky wrote:
>>> PVH guests don't receive ACPI hotplug interrupts and therefore
>>> need to monitor xenstore for CPU hotplug event.
>> Why not?  If they don't, they should.  As we are providing ACPI anyway,
>> we should provide all bits of it.
>
> We don't have IOAPIC, which is how these interrupts are typically
> delivered. I suppose we might be able to specify it as something else.
>
> I'll look into this.


(+Jan)

Yes, we can do this. The main issue is how to deal with event registers 
(i.e FADT.x_pm1a_evt_blk) and AML's PRST region (which specifies online 
CPU map).

Currently these are accessed via IO space and are handled by qemu.

There are a couple of ways to deal with this that I can see.

1. We can implement ioreq handling in the hypervisor, there are only a 
few addresses that need handling.

2. We can implement those registers in memory space and have libxl 
update them them on a hotplug command. This appears to be possible 
because these registers mostly just consume writes without side effects 
so they can be simple memory locations. The one exception is updating 
status bits (they are cleared by writing 1s) but I think we can do this 
from the AML.

Other than that the only other thing is setting up an event channel 
between the toolstack and the guest (either via xenstore or perhaps by 
having a reserved port for SCI).

I have a prototype with (2) (except for the bit clearing part) but I 
want to hear comments on this approach before I write proper patches.

-boris

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[PATCH 0/8] PVH v2 support Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-14 20:20 +0200
  [PATCH 7/8] xen/pvh: PVH guests always have PV devices Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-14 20:20 +0200
    Re: [Xen-devel] [PATCH 7/8] xen/pvh: PVH guests always have PV  devices Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2016-10-14 21:30 +0200
    Re: [PATCH 7/8] xen/pvh: PVH guests always have PV devices Juergen Gross <jgross@suse.com> - 2016-10-18 18:00 +0200
  [PATCH 5/8] xen/pvh: Prevent PVH guests from using PIC, RTC and IOAPIC Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-14 20:20 +0200
    Re: [Xen-devel] [PATCH 5/8] xen/pvh: Prevent PVH guests from using  PIC, RTC and IOAPIC Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2016-10-14 21:20 +0200
      Re: [Xen-devel] [PATCH 5/8] xen/pvh: Prevent PVH guests from using  PIC, RTC and IOAPIC Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-14 21:40 +0200
    Re: [PATCH 5/8] xen/pvh: Prevent PVH guests from using PIC, RTC and  IOAPIC Roger Pau Monné <roger.pau@citrix.com> - 2016-10-26 12:50 +0200
      Re: [PATCH 5/8] xen/pvh: Prevent PVH guests from using PIC, RTC and  IOAPIC Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-26 16:50 +0200
        Re: [PATCH 5/8] xen/pvh: Prevent PVH guests from using PIC, RTC and  IOAPIC Roger Pau Monné <roger.pau@citrix.com> - 2016-10-26 17:20 +0200
          Re: [PATCH 5/8] xen/pvh: Prevent PVH guests from using PIC, RTC and  IOAPIC Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-26 18:10 +0200
  [PATCH 8/8] xen/pvh: Enable CPU hotplug Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-14 20:20 +0200
    Re: [Xen-devel] [PATCH 8/8] xen/pvh: Enable CPU hotplug Andrew Cooper <andrew.cooper3@citrix.com> - 2016-10-14 20:50 +0200
      Re: [Xen-devel] [PATCH 8/8] xen/pvh: Enable CPU hotplug Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-14 21:10 +0200
        Re: [Xen-devel] [PATCH 8/8] xen/pvh: Enable CPU hotplug Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-27 16:30 +0200
          Re: [Xen-devel] [PATCH 8/8] xen/pvh: Enable CPU hotplug Andrew Cooper <andrew.cooper3@citrix.com> - 2016-10-27 17:10 +0200
            Re: [Xen-devel] [PATCH 8/8] xen/pvh: Enable CPU hotplug Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-27 18:30 +0200
  [PATCH 4/8] xen/pvh: Bootstrap PVH guest Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-14 20:20 +0200
    Re: [Xen-devel] [PATCH 4/8] xen/pvh: Bootstrap PVH guest Andrew Cooper <andrew.cooper3@citrix.com> - 2016-10-14 20:50 +0200
      Re: [Xen-devel] [PATCH 4/8] xen/pvh: Bootstrap PVH guest Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-14 21:00 +0200
        Re: [Xen-devel] [PATCH 4/8] xen/pvh: Bootstrap PVH guest Andrew Cooper <andrew.cooper3@citrix.com> - 2016-10-14 21:20 +0200
    Re: [Xen-devel] [PATCH 4/8] xen/pvh: Bootstrap PVH guest Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2016-10-14 21:20 +0200
      Re: [Xen-devel] [PATCH 4/8] xen/pvh: Bootstrap PVH guest Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-14 21:40 +0200
  [PATCH 2/8] x86/head: Refactor 32-bit pgtable setup Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-14 20:20 +0200
    Re: [PATCH 2/8] x86/head: Refactor 32-bit pgtable setup hpa@zytor.com - 2016-10-14 20:40 +0200
      Re: [PATCH 2/8] x86/head: Refactor 32-bit pgtable setup Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-14 20:50 +0200
        Re: [PATCH 2/8] x86/head: Refactor 32-bit pgtable setup hpa@zytor.com - 2016-10-14 21:10 +0200
          Re: [PATCH 2/8] x86/head: Refactor 32-bit pgtable setup Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-14 21:30 +0200
    Re: [PATCH 2/8] x86/head: Refactor 32-bit pgtable setup Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-31 13:40 +0100
  [PATCH 3/8] xen/pvh: Import PVH-related Xen public interfaces Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-14 20:20 +0200
    Re: [Xen-devel] [PATCH 3/8] xen/pvh: Import PVH-related Xen public  interfaces Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2016-10-14 20:40 +0200
    Re: [PATCH 3/8] xen/pvh: Import PVH-related Xen public interfaces Juergen Gross <jgross@suse.com> - 2016-10-21 13:00 +0200
  [PATCH 1/8] xen/x86: Remove PVH support Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-14 20:20 +0200
    Re: [Xen-devel] [PATCH 1/8] xen/x86: Remove PVH support Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2016-10-14 20:40 +0200
    Re: [PATCH 1/8] xen/x86: Remove PVH support Juergen Gross <jgross@suse.com> - 2016-10-18 15:50 +0200
      Re: [PATCH 1/8] xen/x86: Remove PVH support Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-18 16:50 +0200
        Re: [PATCH 1/8] xen/x86: Remove PVH support Juergen Gross <jgross@suse.com> - 2016-10-18 17:40 +0200
          Re: [PATCH 1/8] xen/x86: Remove PVH support Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-10-18 17:50 +0200

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