Re: [Xen-devel] [PATCH] xen/pvhvm: If xen_platform_pci=0 is set don't blow up.

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2013-12-11 at 15:26 -0500, Konrad Rzeszutek Wilk wrote:

> diff --git a/arch/x86/xen/platform-pci-unplug.c 
> b/arch/x86/xen/platform-pci-unplug.c
> index 0a78524..2fb9088 100644
> --- a/arch/x86/xen/platform-pci-unplug.c
> +++ b/arch/x86/xen/platform-pci-unplug.c
> @@ -69,6 +69,75 @@ static int check_platform_magic(void)
>       return 0;
>  }
>  
> +bool xen_has_pv_devices()
> +{
> +     if (!xen_domain())
> +             return false;
> +
> +     /* PV domains always have them. */
> +     if (xen_pv_domain())
> +             return true;
> +
> +     /* And user has xen_platform_pci=0 set in guest config as
> +      * driver did not modify the value. */
> +     if (xen_platform_pci_unplug == 0)
> +             return false;
> +
> +     if (xen_platform_pci_unplug & XEN_UNPLUG_NEVER)
> +             return false;
> +
> +     if (xen_platform_pci_unplug & XEN_UNPLUG_ALL)
> +             return true;
> +
> +     /* And the calleer has to follow with xen_pv_{disk,nic}_devices

"caller" (or "callee"? probably not)

> +      * to be certain which driver can load. */

In the XEN_UNPLUG_UNNECESSARY case won't we end up here and return
false, when in fact this means we have PV devices which we want to use?

> +     return false;
> +}
> +EXPORT_SYMBOL_GPL(xen_has_pv_devices);
> +
> +bool __xen_has_pv_device(int state)

  ^static?

> [...]diff --git a/include/xen/platform_pci.h b/include/xen/platform_pci.h
> index 438c256..b49eeab 100644
> --- a/include/xen/platform_pci.h
> +++ b/include/xen/platform_pci.h
> @@ -48,4 +48,27 @@ static inline int xen_must_unplug_disks(void) {
>  
>  extern int xen_platform_pci_unplug;

I think with all this stuff you could now make xen_platform_pci_unplug
private to the .c file?

> +#if defined(CONFIG_XEN_PVHVM)
> +extern bool xen_has_pv_devices(void);
> +extern bool xen_has_pv_disk_devices(void);
> +extern bool xen_has_pv_nic_devices(void);
> +extern bool xen_has_pv_and_legacy_disk_devices(void);

The logic and usage for all these looked right so far as my cold fuddled
brain could determine.

Ian.


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