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mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-24 05:04:00 +08:00
linux-next/drivers/pci
Keshavamurthy, Anil S 10e5247f40 Intel IOMMU: DMAR detection and parsing logic
This patch supports the upcomming Intel IOMMU hardware a.k.a.  Intel(R)
Virtualization Technology for Directed I/O Architecture and the hardware spec
for the same can be found here
http://www.intel.com/technology/virtualization/index.htm

FAQ! (questions from akpm, answers from ak)

> So...  what's all this code for?
>
> I assume that the intent here is to speed things up under Xen, etc?

Yes in some cases, but not this code.  That would be the Xen version of this
code that could potentially assign whole devices to guests.  I expect this to
be only useful in some special cases though because most hardware is not
virtualizable and you typically want an own instance for each guest.

Ok at some point KVM might implement this too; i likely would use this code
for this.

> Do we
> have any benchmark results to help us to decide whether a merge would be
> justified?

The main advantage for doing it in the normal kernel is not performance, but
more safety.  Broken devices won't be able to corrupt memory by doing random
DMA.

Unfortunately that doesn't work for graphics yet, for that need user space
interfaces for the X server are needed.

There are some potential performance benefits too:

- When you have a device that cannot address the complete address range an
  IOMMU can remap its memory instead of bounce buffering.  Remapping is likely
  cheaper than copying.

- The IOMMU can merge sg lists into a single virtual block.  This could
  potentially speed up SG IO when the device is slow walking SG lists.  [I
  long ago benchmarked 5% on some block benchmark with an old MPT Fusion; but
  it probably depends a lot on the HBA]

And you get better driver debugging because unexpected memory accesses from
the devices will cause a trappable event.

>
> Does it slow anything down?

It adds more overhead to each IO so yes.

This patch:

Add support for early detection and parsing of DMAR's (DMA Remapping) reported
to OS via ACPI tables.

DMA remapping(DMAR) devices support enables independent address translations
for Direct Memory Access(DMA) from Devices.  These DMA remapping devices are
reported via ACPI tables and includes pci device scope covered by these DMA
remapping device.

For detailed info on the specification of "Intel(R) Virtualization Technology
for Directed I/O Architecture" please see
http://www.intel.com/technology/virtualization/index.htm

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>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-22 08:13:18 -07:00
..
hotplug Get rid of unused variable warning in drivers/pci/hotplug/pci_hotplug_core.c 2007-10-15 09:07:58 -07:00
pcie pci: implement "pci=noaer" 2007-10-12 15:03:17 -07:00
.gitignore Add some basic .gitignore files 2005-10-18 08:26:15 -07:00
access.c [PATCH] severing module.h->sched.h 2006-12-04 02:00:22 -05:00
bus.c pci: do not mark exported functions as __devinit 2007-05-02 19:02:35 -07:00
dmar.c Intel IOMMU: DMAR detection and parsing logic 2007-10-22 08:13:18 -07:00
hotplug.c Driver core: change add_uevent_var to use a struct 2007-10-12 14:51:01 -07:00
htirq.c PCI: Use pci_find_ht_capability() in drivers/pci/htirq.c 2006-12-20 10:54:42 -08:00
Kconfig PCI: remove the broken PCI_MULTITHREAD_PROBE option 2007-05-02 19:02:38 -07:00
Makefile Intel IOMMU: DMAR detection and parsing logic 2007-10-22 08:13:18 -07:00
msi.c MSI: Use correct data offset for 32-bit MSI in read_msi_msg() 2007-10-12 15:03:17 -07:00
msi.h PCI: Make some MSI-X #defines generic 2006-12-01 14:36:56 -08:00
pci-acpi.c ACPI: restore CONFIG_ACPI_SLEEP 2007-07-29 16:53:59 -07:00
pci-driver.c Merge master.kernel.org:/pub/scm/linux/kernel/git/gregkh/pci-2.6 2007-10-12 15:50:23 -07:00
pci-sysfs.c Remove capability.h from mm.h 2007-07-16 09:05:45 -07:00
pci.c more trivial signedness fixes in drivers 2007-10-14 12:41:52 -07:00
pci.h Merge master.kernel.org:/pub/scm/linux/kernel/git/gregkh/pci-2.6 2007-10-12 15:50:23 -07:00
probe.c PCI: modify PCI bridge control ISA flag for clarity 2007-10-12 15:03:18 -07:00
proc.c pci: write file size to inode on proc bus file write 2007-10-12 15:03:17 -07:00
quirks.c PCI: re-enable onboard sound on "MSI K8T Neo2-FIR" 2007-10-12 15:03:16 -07:00
remove.c PCI: add pci_stop_bus_device 2006-09-26 17:43:54 -07:00
rom.c [IA64] SN: Correct ROM resource length for BIOS copy 2007-07-09 13:37:18 -07:00
search.c use no_pci_devices() in pci/search.c 2007-07-16 09:05:41 -07:00
setup-bus.c PCI: remove transparent bridge sizing 2007-10-12 15:03:17 -07:00
setup-irq.c kobjects: fix up improper use of the kobject name field 2007-10-12 14:51:02 -07:00
setup-res.c pci: do not mark exported functions as __devinit 2007-05-02 19:02:35 -07:00
syscall.c pci syscall.c: Switch to refcounting API 2007-07-11 16:02:07 -07:00