diff options
author | Keshavamurthy, Anil S | 2007-10-21 16:41:49 -0700 |
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committer | Linus Torvalds | 2007-10-22 08:13:18 -0700 |
commit | ba39592764ed20cee09aae5352e603a27bf56b0d (patch) | |
tree | efe7ec88bbd4d6b08b639830352c68411a7ef7fb /Documentation | |
parent | f8de50eb6b085572ea773f26e066835ea3d3028b (diff) |
Intel IOMMU: Intel IOMMU driver
Actual intel IOMMU driver. Hardware spec can be found at:
http://www.intel.com/technology/virtualization
This driver sets X86_64 'dma_ops', so hook into standard DMA APIs. In this
way, PCI driver will get virtual DMA address. This change is transparent to
PCI drivers.
[akpm@linux-foundation.org: remove unneeded cast]
[akpm@linux-foundation.org: build fix]
[bunk@stusta.de: fix duplicate CONFIG_DMAR Makefile line]
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Muli Ben-Yehuda <muli@il.ibm.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/Intel-IOMMU.txt | 93 | ||||
-rw-r--r-- | Documentation/kernel-parameters.txt | 10 |
2 files changed, 103 insertions, 0 deletions
diff --git a/Documentation/Intel-IOMMU.txt b/Documentation/Intel-IOMMU.txt new file mode 100644 index 000000000000..cbb4dbaef761 --- /dev/null +++ b/Documentation/Intel-IOMMU.txt @@ -0,0 +1,93 @@ +Linux IOMMU Support +=================== + +The architecture spec can be obtained from the below location. + +http://www.intel.com/technology/virtualization/ + +This guide gives a quick cheat sheet for some basic understanding. + +Some Keywords + +DMAR - DMA remapping +DRHD - DMA Engine Reporting Structure +RMRR - Reserved memory Region Reporting Structure +ZLR - Zero length reads from PCI devices +IOVA - IO Virtual address. + +Basic stuff +----------- + +ACPI enumerates and lists the different DMA engines in the platform, and +device scope relationships between PCI devices and which DMA engine controls +them. + +What is RMRR? +------------- + +There are some devices the BIOS controls, for e.g USB devices to perform +PS2 emulation. The regions of memory used for these devices are marked +reserved in the e820 map. When we turn on DMA translation, DMA to those +regions will fail. Hence BIOS uses RMRR to specify these regions along with +devices that need to access these regions. OS is expected to setup +unity mappings for these regions for these devices to access these regions. + +How is IOVA generated? +--------------------- + +Well behaved drivers call pci_map_*() calls before sending command to device +that needs to perform DMA. Once DMA is completed and mapping is no longer +required, device performs a pci_unmap_*() calls to unmap the region. + +The Intel IOMMU driver allocates a virtual address per domain. Each PCIE +device has its own domain (hence protection). Devices under p2p bridges +share the virtual address with all devices under the p2p bridge due to +transaction id aliasing for p2p bridges. + +IOVA generation is pretty generic. We used the same technique as vmalloc() +but these are not global address spaces, but separate for each domain. +Different DMA engines may support different number of domains. + +We also allocate gaurd pages with each mapping, so we can attempt to catch +any overflow that might happen. + + +Graphics Problems? +------------------ +If you encounter issues with graphics devices, you can try adding +option intel_iommu=igfx_off to turn off the integrated graphics engine. + +Some exceptions to IOVA +----------------------- +Interrupt ranges are not address translated, (0xfee00000 - 0xfeefffff). +The same is true for peer to peer transactions. Hence we reserve the +address from PCI MMIO ranges so they are not allocated for IOVA addresses. + +Boot Message Sample +------------------- + +Something like this gets printed indicating presence of DMAR tables +in ACPI. + +ACPI: DMAR (v001 A M I OEMDMAR 0x00000001 MSFT 0x00000097) @ 0x000000007f5b5ef0 + +When DMAR is being processed and initialized by ACPI, prints DMAR locations +and any RMRR's processed. + +ACPI DMAR:Host address width 36 +ACPI DMAR:DRHD (flags: 0x00000000)base: 0x00000000fed90000 +ACPI DMAR:DRHD (flags: 0x00000000)base: 0x00000000fed91000 +ACPI DMAR:DRHD (flags: 0x00000001)base: 0x00000000fed93000 +ACPI DMAR:RMRR base: 0x00000000000ed000 end: 0x00000000000effff +ACPI DMAR:RMRR base: 0x000000007f600000 end: 0x000000007fffffff + +When DMAR is enabled for use, you will notice.. + +PCI-DMA: Using DMAR IOMMU + +TBD +---- + +- For compatibility testing, could use unity map domain for all devices, just + provide a 1-1 for all useful memory under a single domain for all devices. +- API for paravirt ops for abstracting functionlity for VMM folks. diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 6accd360da73..8157417724a8 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -772,6 +772,16 @@ and is between 256 and 4096 characters. It is defined in the file inttest= [IA64] + intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option + off + Disable intel iommu driver. + igfx_off [Default Off] + By default, gfx is mapped as normal device. If a gfx + device has a dedicated DMAR unit, the DMAR unit is + bypassed by not enabling DMAR with this option. In + this case, gfx device will use physical address for + DMA. + io7= [HW] IO7 for Marvel based alpha systems See comment before marvel_specify_io7 in arch/alpha/kernel/core_marvel.c. |