Re: [Xen-devel] Hvmloader: Add _STA for PCI hotplug slots

[Fabio Fantoni <fabio.fantoni@xxxxxxx>]

Il 29/09/2013 02:30, Gonglei (Arei) ha scritto:
> > -----Original Message-----
> > From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@xxxxxxxxxx]
> > Sent: Saturday, September 28, 2013 5:43 AM
> > To: Gonglei (Arei); anthony.perard@xxxxxxxxxx; Stefano Stabellini
> > Cc: xen-devel@xxxxxxxxxxxxx; Hanweidong (Randy); Yanqiangjun; Luonengjun;
> > qemu-devel@xxxxxxxxxx; Gaowei (UVP); Huangweidong (Hardware)
> > Subject: Re: [Xen-devel] Hvmloader: Add _STA for PCI hotplug slots
> >
> > On Fri, Sep 27, 2013 at 06:29:20AM +0000, Gonglei (Arei) wrote:
> > > Hi,
> > Hey,
> >
> > (CCing Stefano and Anthony).
> >
> > > In Xen platform, after using upstream qemu, the all of pci devices will show
> > hotplug in the windows guest.
> > > In this situation, the windows guest may occur blue screen when VM' user
> > click the icon of VGA card for trying unplug VGA card.
> > > However, we don't hope VM's user can do such dangerous operation, and
> > showing all pci devices inside the guest OS is unfriendly.
> > > In addition, I find the traditional qemu have not this problem, and KVM also.
Is there any news about this patch please?

> > > On the KVM platform, the seabios will read the RMV bits of pci slot (according
> > the 0xae08 I/O port register),
> > > then modify the SSDT table.
> > >
> > > The key steps as follows:
> > > In Seabios:
> > > #define PCI_RMV_BASE 0xae0c    // 0xae08 I/O port register
> > > static void* build_ssdt(void)
> > > {
> > >   ...
> > >   // build Device object for each slot
> > >   u32 rmvc_pcrm = inl(PCI_RMV_BASE);
> > >   ...
> > > }
> > >
> > > In upstream Qemu, read 0xae0c I/O port register function:
> > > static uint64_t pci_read(void *opaque, hwaddr addr, unsigned int size)
> > > {
> > >      ...
> > >         case PCI_RMV_BASE - PCI_HOTPLUG_ADDR:
> > >          val = s->pci0_hotplug_enable;
> > >          break;
> > > }
> > > s->pci0_hotplug_enable is set by the follow function:
> > >
> > > static void piix4_update_hotplug(PIIX4PMState *s)
> > > {
> > >         ...
> > >         s->pci0_hotplug_enable = ~0;
> > >      s->pci0_slot_device_present = 0;
> > >
> > >      QTAILQ_FOREACH_SAFE(kid, &bus->children, sibling, next) {
> > >          DeviceState *qdev = kid->child;
> > >          PCIDevice *pdev = PCI_DEVICE(qdev);
> > >          PCIDeviceClass *pc = PCI_DEVICE_GET_CLASS(pdev);
> > >          int slot = PCI_SLOT(pdev->devfn);
> > >
> > >                 //setting by PCIDeviceClass *k->no_hotplug
> > >          if (pc->no_hotplug) {
> > >              s->pci0_hotplug_enable &= ~(1U << slot);
> > >          }
> > >
> > >          s->pci0_slot_device_present |= (1U << slot);
> > >      }
> > > }
> > >
> > > But, on the XEN platform, ACPI DSDT tables is produced by the hvmloader,
> > > more details in this patchï
> > http://xen.1045712.n5.nabble.com/xen-unstable-hvmloader-acpi-dsdt-Fix-PCI-
> > hotplug-with-the-new-qemu-xen-td4947152.html
> > > # Node ID 1a912ce93b506a185b54fd97986214e6eff8a0bc
> > > # Parent  6bc03e22f921aadfa7e5cebe92100cb01377947d
> > > hvmloader/acpi/dsdt: Fix PCI hotplug with the new qemu-xen.
> > oddly enough you did not CC the author of said patch?
> >
> > I am doing that for you.
> That's my mistake, thank you so much!
> > > The ACPI PIIX4 device in QEMU upstream as not the same behavior to
> > > handle PCI hotplug. This patch introduce the necessary change to the
> > > DSDT ACPI table to behave as expceted by the new QEMU.
> > >
> > > To switch to this new DSDT table version, there is a new option
> > > --dm-version to mk_dsdt.
> > >
> > > Change are inspired by SeaBIOS DSDT source code.
> > >
> > > There is few things missing with the new QEMU:
> > >    - QEMU provide the plugged/unplugged status only per slot (and not
> > >      per func like qemu-xen-traditionnal.
> > >    - I did not include the _STA ACPI method that give the status of a
> > >      device (present, functionning properly) because qemu-xen does not
> > >      handle it.
> > >    - I did not include the _RMV method that say if the device can be
> > >      removed,
> > >      because the IO port of QEMU that give this status always return
> > >      true. In
> > >      SeaBIOS table, they have a specific _RMV method for VGA, ISA that
> > >      return
> > >      false. But I'm not sure that we can do the same in Xen.
> > >
> > >
> > > now, I add the _STA method, return the different value according the 0xae08
> > I/O port register on read,
> > > a pci device allow hotplug return 0x1f, a pci device don't allow return 0x1e.
> > > Then the pci devices which don't allow hotplug will not show inside the guest
> > OS.
> >
> > So you are saying that the 'the IO port of QEMU that give this status always
> > return
> > true. " is no longer correct?
> Yes, now the RMV bits of pci slot is set by the PCIDeviceClass's no_hotplug 
> attribute, such as:
>
> static void cirrus_vga_class_init(ObjectClass *klass, void *data)
> {
>      DeviceClass *dc = DEVICE_CLASS(klass);
>      PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
>
>      k->no_hotplug = 1;
>      ... ...
> }
>
> If k->no_hotplug equal 1, the corresponding slot of PIIX4PMState 
> pci0_hotplug_enable bit will be cleared.
> Otherwise the slot's pci0_hotplug_enable bit will be set.
>
> > > Index: tools/firmware/hvmloader/acpi/mk_dsdt.c
> > ================================================================
> > ===
> > > --- tools/firmware/hvmloader/acpi/mk_dsdt.c     (revision 1105)
> > > +++ tools/firmware/hvmloader/acpi/mk_dsdt.c     (working copy)
> > > @@ -437,6 +437,10 @@
> > >           indent(); printf("B0EJ, 32,\n");
> > >           pop_block();
> > >
> > > +        stmt("OperationRegion", "SRMV, SystemIO, 0xae0c, 0x04");
> > > +        push_block("Field", "SRMV, DWordAcc, NoLock, WriteAsZeros");
> > > +        indent(); printf("RMV, 32,\n");
> > > +        pop_block();
> > >           /* hotplug_slot */
> > >           for (slot = 1; slot <= 31; slot++) {
> > >               push_block("Device", "S%i", slot); {
> > > @@ -445,6 +449,14 @@
> > >                       stmt("Store", "ShiftLeft(1, %#06x), B0EJ", slot);
> > >                       stmt("Return", "0x0");
> > >                   } pop_block();
> > > +                push_block("Method", "_STA, 0");{
> > > +                   push_block("If", "And(RMV, ShiftLeft(1, %#06x))",
> > slot);
> > > +                      stmt("Return", "0x1F");
> > > +                   pop_block();
> > > +                   push_block("Else", NULL);
> > > +                      stmt("Return", "0x1E");
> > > +                   pop_block();
> > > +                };pop_block();
> > >                   stmt("Name", "_SUN, %i", slot);
> > >               } pop_block();
> > >           }
> > >
> > > Have you any ideasïExpecting your reply, thanks in advance!
> > >
> > > Best regards,
> > > -Gonglei
> > > _______________________________________________
> > > Xen-devel mailing list
> > > Xen-devel@xxxxxxxxxxxxx
> > > http://lists.xen.org/xen-devel
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxx
> http://lists.xen.org/xen-devel

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel