Re: [Xen-devel] [PATCH V2] x86/AMD-Vi: Fix IVRS HPET special->handle override

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.09.13 at 21:15, <suravee.suthikulpanit@xxxxxxx> wrote:
> --- a/xen/drivers/passthrough/amd/iommu_acpi.c
> +++ b/xen/drivers/passthrough/amd/iommu_acpi.c
> @@ -789,20 +789,25 @@ static u16 __init parse_ivhd_device_special(
>          }
>          break;
>      case ACPI_IVHD_HPET:
> +        if ( hpet_sbdf.cmdline )
> +        {
> +            AMD_IOMMU_DEBUG("IVHD: Command line override present for HPET 
> %#x "
> +                            "(IVRS: %#x devID %04x:%02x:%02x.%u)\n",
> +                            hpet_sbdf.id, special->handle, seg, PCI_BUS(bdf),
> +                            PCI_SLOT(bdf), PCI_FUNC(bdf));
> +            break;
> +        }
> +
>          /* set device id of hpet */
> -        if ( hpet_sbdf.iommu ||
> -             (hpet_sbdf.cmdline && hpet_sbdf.id != special->handle) )
> +        if ( hpet_sbdf.id != 0 )

Surely there's no guarantee that special->handle in non-zero. After
all that's a firmware allocated value. What might be acceptable is
assuming bdf to be non-zero, but even that would look sort of
hackish. Perhaps you'd be better off converting .cmdline to an
enum with states none, cmdline, and ivhd, and use a switch() here.

>          {
>              printk(XENLOG_WARNING "Only one IVHD HPET entry is supported\n");
>              break;
>          }
> +
>          hpet_sbdf.id = special->handle;
> -        if ( !hpet_sbdf.cmdline )
> -        {
> -            hpet_sbdf.bdf = bdf;
> -            hpet_sbdf.seg = seg;
> -        }
> -        hpet_sbdf.iommu = iommu;
> +        hpet_sbdf.bdf = bdf;
> +        hpet_sbdf.seg = seg;
>          break;
>      default:
>          printk(XENLOG_ERR "Unrecognized IVHD special variety %#x\n",
> --- a/xen/drivers/passthrough/amd/iommu_intr.c
> +++ b/xen/drivers/passthrough/amd/iommu_intr.c
> @@ -598,10 +598,9 @@ int __init amd_setup_hpet_msi(struct msi_desc *msi_desc)
>      unsigned long flags;
>      int rc = 0;
>  
> -    if ( msi_desc->hpet_id != hpet_sbdf.id || !hpet_sbdf.iommu )
> +    if ( msi_desc->hpet_id != hpet_sbdf.id )
>      {
> -        AMD_IOMMU_DEBUG("Failed to setup HPET MSI remapping: %s\n",
> -                        hpet_sbdf.iommu ? "Wrong HPET" : "No IOMMU");
> +        AMD_IOMMU_DEBUG("Failed to setup HPET MSI remapping. Mismatch IVRS 
> info.\n");

This will need to get adjusted too - instead of !hpet_sbdf.iommu
you'd now need to check the new enum to be other than "none".

Jan


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