Re: [Xen-devel] [PATCH v2 2/2] xen_platform: SUSE xenlinux unplug for emulated PCI

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 2 Sep 2016, Olaf Hering wrote:
> Implement SUSE specific unplug protocol for emulated PCI devices
> in PVonHVM guests. Its a simple 'outl(1, (ioaddr + 4));'.
> This protocol was implemented and used since Xen 3.0.4.
> It is used in all SUSE/SLES/openSUSE releases up to SLES11SP3 and
> openSUSE 12.3.
> 
> Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
> ---
>  hw/i386/xen/xen_platform.c | 31 ++++++++++++++++++++++++++++++-
>  1 file changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/i386/xen/xen_platform.c b/hw/i386/xen/xen_platform.c
> index 53be3c7..6faee4c 100644
> --- a/hw/i386/xen/xen_platform.c
> +++ b/hw/i386/xen/xen_platform.c
> @@ -313,13 +313,42 @@ static void xen_platform_ioport_writeb(void *opaque, 
> hwaddr addr,
>                                         uint64_t val, unsigned int size)
>  {
>      PCIXenPlatformState *s = opaque;
> +    PCIDevice *pci_dev = PCI_DEVICE(s);
>  
>      switch (addr) {
>      case 0: /* Platform flags */
>          platform_fixed_ioport_writeb(opaque, 0, (uint32_t)val);
>          break;
> +    case 4:
> +        if (val == 1) {
> +            /*
> +             * SUSE unplug for Xenlinux
> +             * xen-kmp used this since xen-3.0.4, instead the official 
> protocol
> +             * from xen-3.3+ It did an unconditional "outl(1, (ioaddr + 4));"
> +             * Pre VMDP 1.7 used 4 and 8 depending on how VMDP was 
> configured.
> +             * If VMDP was to control both disk and LAN it would use 4.
> +             * If it controlled just disk or just LAN, it would use 8 below.
> +             */
> +            blk_drain_all();
> +            blk_flush_all();
> +            pci_unplug_disks(pci_dev->bus);
> +            pci_unplug_nics(pci_dev->bus);
> +        }
> +        break;
>      case 8:
> -        log_writeb(s, (uint32_t)val);
> +        switch (val) {
> +        case 1:
> +            blk_drain_all();
> +            blk_flush_all();
> +            pci_unplug_disks(pci_dev->bus);
> +            break;
> +        case 2:
> +            pci_unplug_nics(pci_dev->bus);
> +            break;
> +        default:
> +            log_writeb(s, (uint32_t)val);
> +            break;

The doc says:

"If VMDP was configured to control just NIC devices it would write the
value 0x1 to offset 0x8. If VMDP was configured to control just storage
devices it would write the value 0x2 to offset 0x8."

So 0x1 to 0x8 to unplug NICs, otherwise 0x2 to 0x8 to unplug storage.
The switch above does the opposite. What am I missing? Am I misreading
the document?

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