Re: [PATCH 2/3] x86/amd-iommu: Work around S3 BIOS bug

Matthew Garrett
2010-09-30T20:21:31Z

On Thu, Sep 23, 2010 at 04:44:48PM +0200, Joerg Roedel wrote:
> +static void iommu_apply_quirks(struct amd_iommu *iommu)
> +{
> + if (is_rd890_iommu(iommu->dev)) {
> + pci_write_config_dword(iommu->dev, 0xf0, iommu->cache_cfg[0]);
> + pci_write_config_dword(iommu->dev, 0xf4, iommu->cache_cfg[1]);
> + pci_write_config_dword(iommu->dev, 0xf8, iommu->cache_cfg[2]);
> + pci_write_config_dword(iommu->dev, 0xfc, iommu->cache_cfg[3]);
> + }
> +}
> +

This doesn't look right. 0xf0-0xff are for indexed register access, so
what you're doing here is just restoring the last of each of those
registers that the BIOS programmed - and if the BIOS cleared the
writable flag afterwards, you're not even doing that.

--
Matthew Garrett | mjg59@srcf.ucam.org