(Based on Ron Minnich's LGUEST_PLAN9_SYSCALL patch).
This patch allows Guests to specify what system call vector they want,
and we try to reserve it. We only allow one non-Linux system call
vector, to try to avoid DoS on the Host.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This is my first step in the migration of page_tables.c to the kernel
types and functions/macros (2.6.23-rc3). Seems to be working OK.
Signed-off-by: Matias Zabaljauregui <matias.zabaljauregui@cern.ch>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Move setup_regs() to lguest_arch_setup_regs() in i386_core.c given
that this is very architecture specific.
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Apply Clue 2x4 to lguest userland<->kernel handling code and the
lguest launcher. Pointers are not to be passed in u32's!
Basic rule of thumb: Anything passing u32's back and forth should be
passing unsigned longs to be portable to 64 bit archs.
For those who forgotten already, I repeat: NO POINTERS IN u32!
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Clean up the hypercall code to make the code in hypercalls.c
architecture independent. First process the common hypercalls and
then call lguest_arch_do_hcall() if the call hasn't been handled.
Rename struct hcall_ring to hcall_args.
This patch requires the previous patch which reorganize the layout of
struct lguest_regs on i386 so they match the layout of struct
hcall_args.
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Currently we look at the "trapnum" to see if the Guest wants a
hypercall. But once the hypercall is done we have to reset trapnum to
a bogus value, otherwise if we exit to userspace and return, we'd run
the same hypercall twice (that was a nasty bug to find!).
This has two main effects:
1) When Jes's patch changes the hypercall args to be a generic "struct
hcall_args" we simply change the type of "lg->hcall". It's set by
arch code, so if it has to copy args or something it can do so, and
point "hcall" into lg->arch somewhere.
2) Async hypercalls only get run when an actual hypercall is pending.
This simplfies the code a little and is a more logical semantic.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Move eax next to ebx/ecx/edx in struct lguest_regs on i386, so they
will be located together and allow it to map directly to a struct
hcall_ring entry (which will be renamed struct hcall_args as in a
subsequent patch).
This is in preparation for making the code hcall code architecture
independent.
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Separate i386 architecture specific from core.c and move it to
x86/core.c and add x86/lguest.h header file to match.
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This simplifies the code a little, in preparation for allowing
alternate system call vectors in guests (Plan 9 uses 0x40).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Back when we had all the Guest state in the switcher, we had a fixed
array of them. This is no longer necessary.
If we switch the network code to using random_ether_addr (46 bits is
enough to avoid clashes), we can get rid of the concept of "guest id"
altogether.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
In order to avoid problematic special linking of the Launcher, we give
the Host an offset: this means we can use any memory region in the
Launcher as Guest memory rather than insisting on mmap() at 0.
The result is quite pleasing: a number of casts are replaced with
simple additions.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
lguest uses a "switcher" shim mapped high to bounce between host and
guest. As lguest becomes less i386-centric, we separate this code
into a subdir.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Lguest has two sides: host support (to launch guests) and guest
support (replacement boot path and paravirt_ops). This moves the
guest side to arch/x86/lguest where it's closer to related code.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Currently lguest will spend a lot of of time waking up the host, as it
cannot go tickless (if the [host] TSC has been marked unstable). On my
laptop I was getting ~40% of wakeups from lguest.
With this patch applied, my laptop is much happier!
Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Use copy_to_user() when copying a struct timespec to the guest -
put_user() cannot handle two long's in one go on a 64bit arch.
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jes Sorensen <jes@sgi.com>
Cc: Al Viro <viro@ftp.linux.org.uk>
1) Group all the "guest OS" support options together, under a PARAVIRT_GUEST
menu.
2) Make those options select CONFIG_PARAVIRT, as suggested by Andi.
3) Make kconfig help titles consistent.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Cc: Zach Amsden <zach@vmware.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Chris Wright <chrisw@sous-sol.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/avi/kvm:
KVM: Use new smp_call_function_mask() in kvm_flush_remote_tlbs()
sched: don't clear PF_VCPU in scheduler
KVM: Improve local apic timer wraparound handling
KVM: Fix local apic timer divide by zero
KVM: Move kvm_guest_exit() after local_irq_enable()
KVM: x86 emulator: fix access registers for instructions with ModR/M byte and Mod = 3
KVM: VMX: Force vm86 mode if setting flags during real mode
KVM: x86 emulator: implement 'movnti mem, reg'
KVM: VMX: Reset mmu context when entering real mode
KVM: VMX: Handle NMIs before enabling interrupts and preemption
KVM: MMU: Set shadow pte atomically in mmu_pte_write_zap_pte()
KVM: x86 emulator: fix repne/repnz decoding
KVM: x86 emulator: fix merge screwup due to emulator split
* 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6: (30 commits)
[IPSEC] IPV6: Fix to add tunnel mode SA correctly.
[NET]: Cut off the queue_mapping field from sk_buff
[NET]: Hide the queue_mapping field inside netif_subqueue_stopped
[NET]: Make and use skb_get_queue_mapping
[NET]: Use the skb_set_queue_mapping where appropriate
[INET]: Use MODULE_ALIAS_NET_PF_PROTO_TYPE where possible.
[INET]: Let inet_diag and friends autoload
[NIU]: Cleanup PAGE_SIZE checks a bit
[NET]: Fix SKB_WITH_OVERHEAD calculation
[ATM]: Fix clip module reload crash.
[TG3]: Update version to 3.85
[TG3]: PCI command adjustment
[TG3]: Add management FW version to ethtool report
[TG3]: Add 5723 support
[Bluetooth] Convert RFCOMM to use kthread API
[Bluetooth] Add constant for Bluetooth socket options level
[Bluetooth] Add support for handling simple eSCO links
[Bluetooth] Add address and channel attribute to RFCOMM TTY device
[Bluetooth] Fix wrong argument in debug code of HIDP
[Bluetooth] Add generic driver for Bluetooth USB devices
...
* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc:
[POWERPC] Enable restart support for lite5200 board
[POWERPC] Add restart support for mpc52xx based platforms
[POWERPC] Update device tree binding for mpc5200 gpt
[POWERPC] Add mpc52xx_find_and_map_path(), refactor utility functions
[POWERPC] bestcomm: Restrict bus prefetch bugfix to original mpc5200 silicon.
* git://git.infradead.org/battery-2.6:
apm_power: calculate to_full/to_empty time using energy
apm_power: improve battery finding algorithm
apm_power: fix obviously wrong logic for time reporting
* 'master' of ssh://master.kernel.org/pub/scm/linux/kernel/git/mchehab/v4l-dvb: (37 commits)
V4L/DVB (6382): saa7134: fix NULL dereference at suspend time for cards without IR receiver
V4L/DVB (6380): ivtvfb: Removal of the 'osd_compat' module option
V4L/DVB (6379): patch which improves GotView Saa7135 remote control
V4L/DVB (6378b): Updates info about the removal of V4L1 at feature-removal-schedule.txt
V4L/DVB (6378a): Removal of VIDIOC_[G|S]_MPEGCOMP from feature-removal-schedule.txt
V4L/DVB (6378): DiB0700-device: Using 1.10 firmware
V4L/DVB (6357): pvrusb2: Improve encoder chip health tracking
V4L/DVB (6356): "while (!ca->wakeup)" breaks the CAM initialisation
V4L/DVB (6352): ir-kbd-i2c: Missing break statement
V4L/DVB (6350): V4L: possible leak in em28xx_init_isoc
V4L/DVB (6348): ivtv: undo video mute when closing the radio
V4L/DVB (6347): ivtv: fix video mute when radio is used
V4L/DVB (6346): ivtvfb: YUV output size fix when ivtvfb is not loaded
V4L/DVB (6345): ivtvfb: YUV handling of an image which is not visible in the display area
V4L/DVB (6343): ivtvfb: check return value of unregister_framebuffer
V4L/DVB (6342): ivtv: fix circular locking (bug 9037)
V4L/DVB (6341): ivtv: fix resizing MPEG1 streams
V4L/DVB (6340): ivtvfb: screen mode change sometimes goes wrong
V4L/DVB (6339): ivtv: set the video color to black instead of green when capturing from the radio
V4L/DVB (6338): ivtv: fix incorrect EBUSY return
...
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6:
firewire: fw-ohci: shut up a superfluous compiler warning
firewire: fw-ohci: log a note about unsupported features
* 'sg' of git://git.kernel.dk/linux-2.6-block:
Add CONFIG_DEBUG_SG sg validation
Change table chaining layout
Update arch/ to use sg helpers
Update swiotlb to use sg helpers
Update net/ to use sg helpers
Update fs/ to use sg helpers
[SG] Update drivers to use sg helpers
[SG] Update crypto/ to sg helpers
[SG] Update block layer to use sg helpers
[SG] Add helpers for manipulating SG entries
New warning since commit ab88ca488b,
"firewire: fw-ohci: missing dma_unmap_single":
drivers/firewire/fw-ohci.c: In function 'at_context_transmit':
drivers/firewire/fw-ohci.c:609: warning: 'payload_bus' may be used
uninitialized in this function
Access to payload_bus is conditional on packet->payload_length > 0,
and that won't change while in at_context_queue_packet.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
because there seems to be more time needed to implement this.
Also, change related error return values to more appropriate ones.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
In kvm_flush_remote_tlbs(), replace a loop using smp_call_function_single()
by a single call to smp_call_function_mask() (which is new for x86_64).
Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>
x86_64 defines ARCH_HAS_SG_CHAIN. So if IOMMU implementations don't
support sg chaining, we will get data corruption.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
pci_dev's->sysdata is highly overloaded and currently IOMMU is broken due
to IOMMU code depending on this field.
This patch introduces new field in pci_dev's dev.archdata struct to hold
IOMMU specific per device IOMMU private data.
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Greg KH <greg@kroah.com>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch adds PageSelectiveInvalidation support replacing existing
DomainSelectiveInvalidation for intel_{map/unmap}_sg() calls and also
enables to mapping one big contiguous DMA virtual address which is mapped
to discontiguous physical address for SG map/unmap calls.
"Doamin selective invalidations" wipes out the IOMMU address translation
cache based on domain ID where as "Page selective invalidations" wipes out
the IOMMU address translation cache for that address mask range which is
more cache friendly when compared to Domain selective invalidations.
Here is how it is done.
1) changes to iova.c
alloc_iova() now takes a bool size_aligned argument, which
when when set, returns the io virtual address that is
naturally aligned to 2 ^ x, where x is the order
of the size requested.
Returning this io vitual address which is naturally
aligned helps iommu to do the "page selective
invalidations" which is IOMMU cache friendly
over "domain selective invalidations".
2) Changes to driver/pci/intel-iommu.c
Clean up intel_{map/unmap}_{single/sg} () calls so that
s/g map/unamp calls is no more dependent on
intel_{map/unmap}_single()
intel_map_sg() now computes the total DMA virtual address
required and allocates the size aligned total DMA virtual address
and maps the discontiguous physical address to the allocated
contiguous DMA virtual address.
In the intel_unmap_sg() case since the DMA virtual address
is contiguous and size_aligned, PageSelectiveInvalidation
is used replacing earlier DomainSelectiveInvalidations.
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Greg KH <greg@kroah.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Suresh B <suresh.b.siddha@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This config option (DMAR_FLPY_WA) sets up 1:1 mapping for the floppy device so
that the floppy device which does not use DMA api's will continue to work.
Once the floppy driver starts using DMA api's this config option can be turn
off or this patch can be yanked out of kernel at that time.
[akpm@linux-foundation.org: cleanups, rename things, build fix]
[jengelh@computergmbh.de: Kconfig fixes]
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: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When we fix all the opensource gfx drivers to use the DMA api's, at that time
we can yank this config options out.
[jengelh@computergmbh.de: Kconfig fixes]
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: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
MSI interrupt handler registrations and fault handling support for Intel-IOMMU
hadrware.
This patch enables the MSI interrupts for the DMA remapping units and in the
interrupt handler read the fault cause and outputs the same on to the console.
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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Intel IOMMU driver needs memory during DMA map calls to setup its internal
page tables and for other data structures. As we all know that these DMA map
calls are mostly called in the interrupt context or with the spinlock held by
the upper level drivers(network/storage drivers), so in order to avoid any
memory allocation failure due to low memory issues, this patch makes memory
allocation by temporarily setting PF_MEMALLOC flags for the current task
before making memory allocation calls.
We evaluated mempools as a backup when kmem_cache_alloc() fails
and found that mempools are really not useful here because
1) We don't know for sure how much to reserve in advance
2) And mempools are not useful for GFP_ATOMIC case (as we call
memory alloc functions with GFP_ATOMIC)
(akpm: point 2 is wrong...)
With PF_MEMALLOC flag set in the current->flags, the VM subsystem avoids any
watermark checks before allocating memory thus guarantee'ing the memory till
the last free page. Further, looking at the code in mm/page_alloc.c in
__alloc_pages() function, looks like this flag is useful only in the
non-interrupt context.
If we are in the interrupt context and memory allocation in IOMMU driver fails
for some reason, then the DMA map api's will return failure and it is up to
the higher level drivers to retry. Suppose, if upper level driver programs
the controller with the buggy DMA virtual address, the IOMMU will block that
DMA transaction when that happens thus preventing any corruption to main
memory.
So far in our test scenario, we were unable to create any memory allocation
failure inside dma map api calls.
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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
This code implements a generic IOVA allocation and management. As per Dave's
suggestion we are now allocating IO virtual address from Higher DMA limit
address rather than lower end address and this eliminated the need to preserve
the IO virtual address for multiple devices sharing the same domain virtual
address.
Also this code uses red black trees to store the allocated and reserved iova
nodes. This showed a good performance improvements over previous linear
linked list.
[akpm@linux-foundation.org: remove inlines]
[akpm@linux-foundation.org: coding style fixes]
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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When devices are under a p2p bridge, upstream transactions get replaced by the
device id of the bridge as it owns the PCIE transaction. Hence its necessary
to setup translations on behalf of the bridge as well. Due to this limitation
all devices under a p2p share the same domain in a DMAR.
We just cache the type of device, if its a native PCIe device
or not for later use.
[akpm@linux-foundation.org: BUG_ON -> WARN_ON+recover]
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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
Current memory notifier has some defects yet. (Fortunately, nothing uses
it.) This patch is to fix and rearrange for them.
- Add information of start_pfn, nr_pages, and node id if node status is
changes from/to memoryless node for callback functions.
Callbacks can't do anything without those information.
- Add notification going-online status.
It is necessary for creating per node structure before the node's
pages are available.
- Move GOING_OFFLINE status notification after page isolation.
It is good place for return memory like cache for callback,
because returned page is not used again.
- Make CANCEL events for rollingback when error occurs.
- Delete MEM_MAPPING_INVALID notification. It will be not used.
- Fix compile error of (un)register_memory_notifier().
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Calling saa7134_ir_stop at suspend is no good idea
for saa7134 cards without remote control.
Signed-off-by: Matthias Schwarzott <zzam@gentoo.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Due to changes in the core ivtv driver as of release 1.0, the osd_compat
module option has been rendered obsolete. This patch removes the option and
all code associated with it.
Signed-off-by: Ian Armstrong <ian@iarmst.demon.co.uk>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
