2012-02-02 23:57:10

by Mike Travis

Subject: [PATCH 1/3] x86 PCI: Fix identity mapping for sandy bridge

With SandyBridge, Intel has changed these Socket PCI devices to have a class
type of "System Peripheral" & "Performance counter", rather than "HostBridge".
So instead of using a "special" case to detect which devices will not be
doing DMA, use the fact that a device that is not associated with an IOMMU,
will not need an identity map.

Signed-off-by: Mike Travis <[email protected]>
Signed-off-by: Mike Habeck <[email protected]>
---
drivers/iommu/intel-iommu.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)

--- linux.orig/drivers/iommu/intel-iommu.c
+++ linux/drivers/iommu/intel-iommu.c
@@ -48,8 +48,6 @@
#define ROOT_SIZE VTD_PAGE_SIZE
#define CONTEXT_SIZE VTD_PAGE_SIZE

-#define IS_BRIDGE_HOST_DEVICE(pdev) \
- ((pdev->class >> 8) == PCI_CLASS_BRIDGE_HOST)
#define IS_GFX_DEVICE(pdev) ((pdev->class >> 16) == PCI_BASE_CLASS_DISPLAY)
#define IS_ISA_DEVICE(pdev) ((pdev->class >> 8) == PCI_CLASS_BRIDGE_ISA)
#define IS_AZALIA(pdev) ((pdev)->vendor == 0x8086 && (pdev)->device == 0x3a3e)
@@ -2369,18 +2367,18 @@ static int __init iommu_prepare_static_i
return -EFAULT;

for_each_pci_dev(pdev) {
- /* Skip Host/PCI Bridge devices */
- if (IS_BRIDGE_HOST_DEVICE(pdev))
- continue;
if (iommu_should_identity_map(pdev, 1)) {
- printk(KERN_INFO "IOMMU: %s identity mapping for device %s\n",
- hw ? "hardware" : "software", pci_name(pdev));
-
ret = domain_add_dev_info(si_domain, pdev,
- hw ? CONTEXT_TT_PASS_THROUGH :
- CONTEXT_TT_MULTI_LEVEL);
- if (ret)
+ hw ? CONTEXT_TT_PASS_THROUGH :
+ CONTEXT_TT_MULTI_LEVEL);
+ if (ret) {
+ /* device not associated with an iommu */
+ if (ret == -ENODEV)
+ continue;
return ret;
+ }
+ pr_info("IOMMU: %s identity mapping for device %s\n",
+ hw ? "hardware" : "software", pci_name(pdev));
}
}


--

2012-02-22 20:20:06

by Andrew Morton

Subject: Re: [PATCH 1/3] x86 PCI: Fix identity mapping for sandy bridge

On Thu, 02 Feb 2012 17:56:51 -0600
Mike Travis <[email protected]> wrote:

> --- linux.orig/drivers/iommu/intel-iommu.c
> +++ linux/drivers/iommu/intel-iommu.c
> @@ -48,8 +48,6 @@
> #define ROOT_SIZE VTD_PAGE_SIZE
> #define CONTEXT_SIZE VTD_PAGE_SIZE
>
> -#define IS_BRIDGE_HOST_DEVICE(pdev) \
> - ((pdev->class >> 8) == PCI_CLASS_BRIDGE_HOST)
> #define IS_GFX_DEVICE(pdev) ((pdev->class >> 16) == PCI_BASE_CLASS_DISPLAY)
> #define IS_ISA_DEVICE(pdev) ((pdev->class >> 8) == PCI_CLASS_BRIDGE_ISA)
> #define IS_AZALIA(pdev) ((pdev)->vendor == 0x8086 && (pdev)->device == 0x3a3e)

I suppose it would be tiresome to point out what happens when someone
does IS_GFX_DEVICE(pdev + 1).

Macros: Just Don't Do It.