Commit Graph

35 Commits

Author SHA1 Message Date
Paul Mackerras
297e21053a KVM: Give IRQFD its own separate enabling Kconfig option
Currently, the IRQFD code is conditional on CONFIG_HAVE_KVM_IRQ_ROUTING.
So that we can have the IRQFD code compiled in without having the
IRQ routing code, this creates a new CONFIG_HAVE_KVM_IRQFD, makes
the IRQFD code conditional on it instead of CONFIG_HAVE_KVM_IRQ_ROUTING,
and makes all the platforms that currently select HAVE_KVM_IRQ_ROUTING
also select HAVE_KVM_IRQFD.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Tested-by: Eric Auger <eric.auger@linaro.org>
Tested-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-08-05 14:26:28 +02:00
Randy Dunlap
94491620e1 kvm: make KVM_MMU_AUDIT help text more readable
Make KVM_MMU_AUDIT kconfig help text readable and collapse
two spaces between words down to one space.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-01-20 12:59:26 +01:00
Alex Williamson
ec53500fae kvm: Add VFIO device
So far we've succeeded at making KVM and VFIO mostly unaware of each
other, but areas are cropping up where a connection beyond eventfds
and irqfds needs to be made.  This patch introduces a KVM-VFIO device
that is meant to be a gateway for such interaction.  The user creates
the device and can add and remove VFIO groups to it via file
descriptors.  When a group is added, KVM verifies the group is valid
and gets a reference to it via the VFIO external user interface.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-10-30 19:02:03 +01:00
Alex Williamson
2a5bab1004 kvm: Allow build-time configuration of KVM device assignment
We hope to at some point deprecate KVM legacy device assignment in
favor of VFIO-based assignment.  Towards that end, allow legacy
device assignment to be deconfigured.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-04-28 12:58:56 +03:00
Alexander Graf
a725d56a02 KVM: Introduce CONFIG_HAVE_KVM_IRQ_ROUTING
Quite a bit of code in KVM has been conditionalized on availability of
IOAPIC emulation. However, most of it is generically applicable to
platforms that don't have an IOPIC, but a different type of irq chip.

Make code that only relies on IRQ routing, not an APIC itself, on
CONFIG_HAVE_KVM_IRQ_ROUTING, so that we can reuse it later.

Signed-off-by: Alexander Graf <agraf@suse.de>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
2013-04-26 20:27:14 +02:00
Liu, Jinsong
92b5265d38 KVM: Depend on HIGH_RES_TIMERS
KVM lapic timer and tsc deadline timer based on hrtimer,
setting a leftmost node to rb tree and then do hrtimer reprogram.
If hrtimer not configured as high resolution, hrtimer_enqueue_reprogram
do nothing and then make kvm lapic timer and tsc deadline timer fail.

Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2012-09-10 11:10:03 +03:00
Raghavendra K T
f2a7434731 KVM: Add config to support ple or cpu relax optimzation
Suggested-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com> # on s390x
Signed-off-by: Avi Kivity <avi@redhat.com>
2012-07-23 13:00:53 +03:00
Jan Kiszka
07975ad3b3 KVM: Introduce direct MSI message injection for in-kernel irqchips
Currently, MSI messages can only be injected to in-kernel irqchips by
defining a corresponding IRQ route for each message. This is not only
unhandy if the MSI messages are generated "on the fly" by user space,
IRQ routes are a limited resource that user space has to manage
carefully.

By providing a direct injection path, we can both avoid using up limited
resources and simplify the necessary steps for user land.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2012-04-24 15:59:47 +03:00
Gleb Natapov
f5132b0138 KVM: Expose a version 2 architectural PMU to a guests
Use perf_events to emulate an architectural PMU, version 2.

Based on PMU version 1 emulation by Avi Kivity.

[avi: adjust for cpuid.c]
[jan: fix anonymous field initialization for older gcc]

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2011-12-27 11:24:29 +02:00
Avi Kivity
43771ebfc9 KVM: Make KVM_INTEL depend on CPU_SUP_INTEL
PMU virtualization needs to talk to Intel-specific bits of perf; these are
only available when CPU_SUP_INTEL=y.

Fixes

  arch/x86/built-in.o: In function `atomic_switch_perf_msrs':
  vmx.c:(.text+0x6b1d4): undefined reference to `perf_guest_get_msrs'

Reported-by: Ingo Molnar <mingo@elte.hu>
Reported-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2011-12-27 11:22:27 +02:00
Randy Dunlap
df3d8ae1f8 KVM: uses TASKSTATS, depends on NET
CONFIG_TASKSTATS just had a change to use netlink, including
a change to "depends on NET".  Since "select" does not follow
dependencies, KVM also needs to depend on NET to prevent build
errors when CONFIG_NET is not enabled.

Sample of the reported "undefined reference" build errors:

taskstats.c:(.text+0x8f686): undefined reference to `nla_put'
taskstats.c:(.text+0x8f721): undefined reference to `nla_reserve'
taskstats.c:(.text+0x8f8fb): undefined reference to `init_net'
taskstats.c:(.text+0x8f905): undefined reference to `netlink_unicast'
taskstats.c:(.text+0x8f934): undefined reference to `kfree_skb'
taskstats.c:(.text+0x8f9e9): undefined reference to `skb_clone'
taskstats.c:(.text+0x90060): undefined reference to `__alloc_skb'
taskstats.c:(.text+0x901e9): undefined reference to `skb_put'
taskstats.c:(.init.text+0x4665): undefined reference to `genl_register_family'
taskstats.c:(.init.text+0x4699): undefined reference to `genl_register_ops'
taskstats.c:(.init.text+0x4710): undefined reference to `genl_unregister_ops'
taskstats.c:(.init.text+0x471c): undefined reference to `genl_unregister_family'

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2011-08-16 19:00:41 +03:00
Randy Dunlap
fd079facb3 KVM: fix TASK_DELAY_ACCT kconfig warning
Fix kconfig dependency warning:

warning: (KVM) selects TASK_DELAY_ACCT which has unmet direct dependencies (TASKSTATS)

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Avi Kivity <avi@redhat.com>
2011-07-27 14:22:06 +03:00
Linus Torvalds
5fabc487c9 Merge branch 'kvm-updates/3.1' of git://git.kernel.org/pub/scm/virt/kvm/kvm
* 'kvm-updates/3.1' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (143 commits)
  KVM: IOMMU: Disable device assignment without interrupt remapping
  KVM: MMU: trace mmio page fault
  KVM: MMU: mmio page fault support
  KVM: MMU: reorganize struct kvm_shadow_walk_iterator
  KVM: MMU: lockless walking shadow page table
  KVM: MMU: do not need atomicly to set/clear spte
  KVM: MMU: introduce the rules to modify shadow page table
  KVM: MMU: abstract some functions to handle fault pfn
  KVM: MMU: filter out the mmio pfn from the fault pfn
  KVM: MMU: remove bypass_guest_pf
  KVM: MMU: split kvm_mmu_free_page
  KVM: MMU: count used shadow pages on prepareing path
  KVM: MMU: rename 'pt_write' to 'emulate'
  KVM: MMU: cleanup for FNAME(fetch)
  KVM: MMU: optimize to handle dirty bit
  KVM: MMU: cache mmio info on page fault path
  KVM: x86: introduce vcpu_mmio_gva_to_gpa to cleanup the code
  KVM: MMU: do not update slot bitmap if spte is nonpresent
  KVM: MMU: fix walking shadow page table
  KVM guest: KVM Steal time registration
  ...
2011-07-24 09:07:03 -07:00
Ohad Ben-Cohen
e72542191c virtio: expose for non-virtualization users too
virtio has been so far used only in the context of virtualization,
and the virtio Kconfig was sourced directly by the relevant arch
Kconfigs when VIRTUALIZATION was selected.

Now that we start using virtio for inter-processor communications,
we need to source the virtio Kconfig outside of the virtualization
scope too.

Moreover, some architectures might use virtio for both virtualization
and inter-processor communications, so directly sourcing virtio
might yield unexpected results due to conflicting selections.

The simple solution offered by this patch is to always source virtio's
Kconfig in drivers/Kconfig, and remove it from the appropriate arch
Kconfigs. Additionally, a virtio menu entry has been added so virtio
drivers don't show up in the general drivers menu.

This way anyone can use virtio, though it's arguably less accessible
(and neat!) for virtualization users now.

Note: some architectures (mips and sh) seem to have a VIRTUALIZATION
menu merely for sourcing virtio's Kconfig, so that menu is removed too.

Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-07-23 16:20:30 +09:30
Glauber Costa
c9aaa8957f KVM: Steal time implementation
To implement steal time, we need the hypervisor to pass the guest
information about how much time was spent running other processes
outside the VM, while the vcpu had meaningful work to do - halt
time does not count.

This information is acquired through the run_delay field of
delayacct/schedstats infrastructure, that counts time spent in a
runqueue but not running.

Steal time is a per-cpu information, so the traditional MSR-based
infrastructure is used. A new msr, KVM_MSR_STEAL_TIME, holds the
memory area address containing information about steal time

This patch contains the hypervisor part of the steal time infrasructure,
and can be backported independently of the guest portion.

[avi, yongjie: export delayacct_on, to avoid build failures in some configs]

Signed-off-by: Glauber Costa <glommer@redhat.com>
Tested-by: Eric B Munson <emunson@mgebm.net>
CC: Rik van Riel <riel@redhat.com>
CC: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Yongjie Ren <yongjie.ren@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2011-07-14 12:59:14 +03:00
Gleb Natapov
af585b921e KVM: Halt vcpu if page it tries to access is swapped out
If a guest accesses swapped out memory do not swap it in from vcpu thread
context. Schedule work to do swapping and put vcpu into halted state
instead.

Interrupts will still be delivered to the guest and if interrupt will
cause reschedule guest will continue to run another task.

[avi: remove call to get_user_pages_noio(), nacked by Linus; this
      makes everything synchrnous again]

Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2011-01-12 11:21:39 +02:00
Xiao Guangrong
8b1fe17cc7 KVM: MMU: support disable/enable mmu audit dynamicly
Add a r/w module parameter named 'mmu_audit', it can control audit
enable/disable:

enable:
  echo 1 > /sys/module/kvm/parameters/mmu_audit

disable:
  echo 0 > /sys/module/kvm/parameters/mmu_audit

This patch not change the logic

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2010-10-24 10:51:56 +02:00
Linus Torvalds
c812a51d11 Merge branch 'kvm-updates/2.6.34' of git://git.kernel.org/pub/scm/virt/kvm/kvm
* 'kvm-updates/2.6.34' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (145 commits)
  KVM: x86: Add KVM_CAP_X86_ROBUST_SINGLESTEP
  KVM: VMX: Update instruction length on intercepted BP
  KVM: Fix emulate_sys[call, enter, exit]()'s fault handling
  KVM: Fix segment descriptor loading
  KVM: Fix load_guest_segment_descriptor() to inject page fault
  KVM: x86 emulator: Forbid modifying CS segment register by mov instruction
  KVM: Convert kvm->requests_lock to raw_spinlock_t
  KVM: Convert i8254/i8259 locks to raw_spinlocks
  KVM: x86 emulator: disallow opcode 82 in 64-bit mode
  KVM: x86 emulator: code style cleanup
  KVM: Plan obsolescence of kernel allocated slots, paravirt mmu
  KVM: x86 emulator: Add LOCK prefix validity checking
  KVM: x86 emulator: Check CPL level during privilege instruction emulation
  KVM: x86 emulator: Fix popf emulation
  KVM: x86 emulator: Check IOPL level during io instruction emulation
  KVM: x86 emulator: fix memory access during x86 emulation
  KVM: x86 emulator: Add Virtual-8086 mode of emulation
  KVM: x86 emulator: Add group9 instruction decoding
  KVM: x86 emulator: Add group8 instruction decoding
  KVM: do not store wqh in irqfd
  ...

Trivial conflicts in Documentation/feature-removal-schedule.txt
2010-03-05 13:12:34 -08:00
Avi Kivity
50eb2a3cd0 KVM: Add KVM_MMIO kconfig item
s390 doesn't have mmio, this will simplify ifdefing it out.

Signed-off-by: Avi Kivity <avi@redhat.com>
2010-03-01 12:35:41 -03:00
Michael S. Tsirkin
3a4d5c94e9 vhost_net: a kernel-level virtio server
What it is: vhost net is a character device that can be used to reduce
the number of system calls involved in virtio networking.
Existing virtio net code is used in the guest without modification.

There's similarity with vringfd, with some differences and reduced scope
- uses eventfd for signalling
- structures can be moved around in memory at any time (good for
  migration, bug work-arounds in userspace)
- write logging is supported (good for migration)
- support memory table and not just an offset (needed for kvm)

common virtio related code has been put in a separate file vhost.c and
can be made into a separate module if/when more backends appear.  I used
Rusty's lguest.c as the source for developing this part : this supplied
me with witty comments I wouldn't be able to write myself.

What it is not: vhost net is not a bus, and not a generic new system
call. No assumptions are made on how guest performs hypercalls.
Userspace hypervisors are supported as well as kvm.

How it works: Basically, we connect virtio frontend (configured by
userspace) to a backend. The backend could be a network device, or a tap
device.  Backend is also configured by userspace, including vlan/mac
etc.

Status: This works for me, and I haven't see any crashes.
Compared to userspace, people reported improved latency (as I save up to
4 system calls per packet), as well as better bandwidth and CPU
utilization.

Features that I plan to look at in the future:
- mergeable buffers
- zero copy
- scalability tuning: figure out the best threading model to use

Note on RCU usage (this is also documented in vhost.h, near
private_pointer which is the value protected by this variant of RCU):
what is happening is that the rcu_dereference() is being used in a
workqueue item.  The role of rcu_read_lock() is taken on by the start of
execution of the workqueue item, of rcu_read_unlock() by the end of
execution of the workqueue item, and of synchronize_rcu() by
flush_workqueue()/flush_work(). In the future we might need to apply
some gcc attribute or sparse annotation to the function passed to
INIT_WORK(). Paul's ack below is for this RCU usage.

(Includes fixes by Alan Cox <alan@linux.intel.com>,
David L Stevens <dlstevens@us.ibm.com>,
Chris Wright <chrisw@redhat.com>)

Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-01-15 01:43:29 -08:00
Avi Kivity
18863bdd60 KVM: x86 shared msr infrastructure
The various syscall-related MSRs are fairly expensive to switch.  Currently
we switch them on every vcpu preemption, which is far too often:

- if we're switching to a kernel thread (idle task, threaded interrupt,
  kernel-mode virtio server (vhost-net), for example) and back, then
  there's no need to switch those MSRs since kernel threasd won't
  be exiting to userspace.

- if we're switching to another guest running an identical OS, most likely
  those MSRs will have the same value, so there's little point in reloading
  them.

- if we're running the same OS on the guest and host, the MSRs will have
  identical values and reloading is unnecessary.

This patch uses the new user return notifiers to implement last-minute
switching, and checks the msr values to avoid unnecessary reloading.

Signed-off-by: Avi Kivity <avi@redhat.com>
2009-12-03 09:32:21 +02:00
Marcelo Tosatti
2023a29cbe KVM: remove old KVMTRACE support code
Return EOPNOTSUPP for KVM_TRACE_ENABLE/PAUSE/DISABLE ioctls.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2009-09-10 08:33:03 +03:00
Gleb Natapov
73880c80aa KVM: Break dependency between vcpu index in vcpus array and vcpu_id.
Archs are free to use vcpu_id as they see fit. For x86 it is used as
vcpu's apic id. New ioctl is added to configure boot vcpu id that was
assumed to be 0 till now.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2009-09-10 08:32:52 +03:00
Gregory Haskins
721eecbf4f KVM: irqfd
KVM provides a complete virtual system environment for guests, including
support for injecting interrupts modeled after the real exception/interrupt
facilities present on the native platform (such as the IDT on x86).
Virtual interrupts can come from a variety of sources (emulated devices,
pass-through devices, etc) but all must be injected to the guest via
the KVM infrastructure.  This patch adds a new mechanism to inject a specific
interrupt to a guest using a decoupled eventfd mechnanism:  Any legal signal
on the irqfd (using eventfd semantics from either userspace or kernel) will
translate into an injected interrupt in the guest at the next available
interrupt window.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2009-09-10 08:32:41 +03:00
Avi Kivity
0ba12d1081 KVM: Move common KVM Kconfig items to new file virt/kvm/Kconfig
Reduce Kconfig code duplication.

Signed-off-by: Avi Kivity <avi@redhat.com>
2009-09-10 08:32:41 +03:00
Robert P. J. Day
58f8ac279a KVM: Expand on "help" info to specify kvm intel and amd module names
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Avi Kivity <avi@redhat.com>
2009-06-10 11:48:55 +03:00
Ingo Molnar
8302294f43 Merge branch 'tracing/core-v2' into tracing-for-linus
Conflicts:
	include/linux/slub_def.h
	lib/Kconfig.debug
	mm/slob.c
	mm/slub.c
2009-04-02 00:49:02 +02:00
Avi Kivity
5d9b8e30f5 KVM: Add CONFIG_HAVE_KVM_IRQCHIP
Two KVM archs support irqchips and two don't.  Add a Kconfig item to
make selecting between the two models easier.

Signed-off-by: Avi Kivity <avi@redhat.com>
2009-03-24 11:03:02 +02:00
Ingo Molnar
b6ab4afee4 tracing, kvm: change MARKERS to select instead of depends on
Impact: build fix

fix:

 kernel/trace/Kconfig:42:error: found recursive dependency: TRACING ->
 TRACEPOINTS -> MARKERS -> KVM_TRACE -> RELAY -> KMEMTRACE -> TRACING

markers is a facility that should be selected - not depended on
by an interactive Kconfig entry.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-30 09:41:04 +01:00
Avi Kivity
ca93e992fd KVM: Require the PCI subsystem
PCI device assignment makes calls to pci code, so require it to be built
into the kernel.

Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-11-11 20:56:13 +02:00
Andrea Arcangeli
cddb8a5c14 mmu-notifiers: core
With KVM/GFP/XPMEM there isn't just the primary CPU MMU pointing to pages.
 There are secondary MMUs (with secondary sptes and secondary tlbs) too.
sptes in the kvm case are shadow pagetables, but when I say spte in
mmu-notifier context, I mean "secondary pte".  In GRU case there's no
actual secondary pte and there's only a secondary tlb because the GRU
secondary MMU has no knowledge about sptes and every secondary tlb miss
event in the MMU always generates a page fault that has to be resolved by
the CPU (this is not the case of KVM where the a secondary tlb miss will
walk sptes in hardware and it will refill the secondary tlb transparently
to software if the corresponding spte is present).  The same way
zap_page_range has to invalidate the pte before freeing the page, the spte
(and secondary tlb) must also be invalidated before any page is freed and
reused.

Currently we take a page_count pin on every page mapped by sptes, but that
means the pages can't be swapped whenever they're mapped by any spte
because they're part of the guest working set.  Furthermore a spte unmap
event can immediately lead to a page to be freed when the pin is released
(so requiring the same complex and relatively slow tlb_gather smp safe
logic we have in zap_page_range and that can be avoided completely if the
spte unmap event doesn't require an unpin of the page previously mapped in
the secondary MMU).

The mmu notifiers allow kvm/GRU/XPMEM to attach to the tsk->mm and know
when the VM is swapping or freeing or doing anything on the primary MMU so
that the secondary MMU code can drop sptes before the pages are freed,
avoiding all page pinning and allowing 100% reliable swapping of guest
physical address space.  Furthermore it avoids the code that teardown the
mappings of the secondary MMU, to implement a logic like tlb_gather in
zap_page_range that would require many IPI to flush other cpu tlbs, for
each fixed number of spte unmapped.

To make an example: if what happens on the primary MMU is a protection
downgrade (from writeable to wrprotect) the secondary MMU mappings will be
invalidated, and the next secondary-mmu-page-fault will call
get_user_pages and trigger a do_wp_page through get_user_pages if it
called get_user_pages with write=1, and it'll re-establishing an updated
spte or secondary-tlb-mapping on the copied page.  Or it will setup a
readonly spte or readonly tlb mapping if it's a guest-read, if it calls
get_user_pages with write=0.  This is just an example.

This allows to map any page pointed by any pte (and in turn visible in the
primary CPU MMU), into a secondary MMU (be it a pure tlb like GRU, or an
full MMU with both sptes and secondary-tlb like the shadow-pagetable layer
with kvm), or a remote DMA in software like XPMEM (hence needing of
schedule in XPMEM code to send the invalidate to the remote node, while no
need to schedule in kvm/gru as it's an immediate event like invalidating
primary-mmu pte).

At least for KVM without this patch it's impossible to swap guests
reliably.  And having this feature and removing the page pin allows
several other optimizations that simplify life considerably.

Dependencies:

1) mm_take_all_locks() to register the mmu notifier when the whole VM
   isn't doing anything with "mm".  This allows mmu notifier users to keep
   track if the VM is in the middle of the invalidate_range_begin/end
   critical section with an atomic counter incraese in range_begin and
   decreased in range_end.  No secondary MMU page fault is allowed to map
   any spte or secondary tlb reference, while the VM is in the middle of
   range_begin/end as any page returned by get_user_pages in that critical
   section could later immediately be freed without any further
   ->invalidate_page notification (invalidate_range_begin/end works on
   ranges and ->invalidate_page isn't called immediately before freeing
   the page).  To stop all page freeing and pagetable overwrites the
   mmap_sem must be taken in write mode and all other anon_vma/i_mmap
   locks must be taken too.

2) It'd be a waste to add branches in the VM if nobody could possibly
   run KVM/GRU/XPMEM on the kernel, so mmu notifiers will only enabled if
   CONFIG_KVM=m/y.  In the current kernel kvm won't yet take advantage of
   mmu notifiers, but this already allows to compile a KVM external module
   against a kernel with mmu notifiers enabled and from the next pull from
   kvm.git we'll start using them.  And GRU/XPMEM will also be able to
   continue the development by enabling KVM=m in their config, until they
   submit all GRU/XPMEM GPLv2 code to the mainline kernel.  Then they can
   also enable MMU_NOTIFIERS in the same way KVM does it (even if KVM=n).
   This guarantees nobody selects MMU_NOTIFIER=y if KVM and GRU and XPMEM
   are all =n.

The mmu_notifier_register call can fail because mm_take_all_locks may be
interrupted by a signal and return -EINTR.  Because mmu_notifier_reigster
is used when a driver startup, a failure can be gracefully handled.  Here
an example of the change applied to kvm to register the mmu notifiers.
Usually when a driver startups other allocations are required anyway and
-ENOMEM failure paths exists already.

 struct  kvm *kvm_arch_create_vm(void)
 {
        struct kvm *kvm = kzalloc(sizeof(struct kvm), GFP_KERNEL);
+       int err;

        if (!kvm)
                return ERR_PTR(-ENOMEM);

        INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);

+       kvm->arch.mmu_notifier.ops = &kvm_mmu_notifier_ops;
+       err = mmu_notifier_register(&kvm->arch.mmu_notifier, current->mm);
+       if (err) {
+               kfree(kvm);
+               return ERR_PTR(err);
+       }
+
        return kvm;
 }

mmu_notifier_unregister returns void and it's reliable.

The patch also adds a few needed but missing includes that would prevent
kernel to compile after these changes on non-x86 archs (x86 didn't need
them by luck).

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix mm/filemap_xip.c build]
[akpm@linux-foundation.org: fix mm/mmu_notifier.c build]
Signed-off-by: Andrea Arcangeli <andrea@qumranet.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Kanoj Sarcar <kanojsarcar@yahoo.com>
Cc: Roland Dreier <rdreier@cisco.com>
Cc: Steve Wise <swise@opengridcomputing.com>
Cc: Avi Kivity <avi@qumranet.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Anthony Liguori <aliguori@us.ibm.com>
Cc: Chris Wright <chrisw@redhat.com>
Cc: Marcelo Tosatti <marcelo@kvack.org>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Izik Eidus <izike@qumranet.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-28 16:30:21 -07:00
Feng(Eric) Liu
d4c9ff2d1b KVM: Add kvm trace userspace interface
This interface allows user a space application to read the trace of kvm
related events through relayfs.

Signed-off-by: Feng (Eric) Liu <eric.e.liu@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 12:01:22 +03:00
Avi Kivity
268fe02ae0 KVM: no longer EXPERIMENTAL
Long overdue.

Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 12:00:36 +03:00
Anthony Liguori
0ad07ec1fd virtio: Put the virtio under the virtualization menu
This patch moves virtio under the virtualization menu and changes virtio
devices to not claim to only be for lguest.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04 23:50:05 +11:00
Avi Kivity
edf884172e KVM: Move arch dependent files to new directory arch/x86/kvm/
This paves the way for multiple architecture support.  Note that while
ioapic.c could potentially be shared with ia64, it is also moved.

Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-01-30 18:01:18 +02:00