This lifts the restriction that book3s_hv guests can only run one
hardware thread per core, and allows them to use up to 4 threads
per core on POWER7.  The host still has to run single-threaded.

This capability is advertised to qemu through a new KVM_CAP_PPC_SMT
capability.  The return value of the ioctl querying this capability
is the number of vcpus per virtual CPU core (vcore), currently 4.

To use this, the host kernel should be booted with all threads
active, and then all the secondary threads should be offlined.
This will put the secondary threads into nap mode.  KVM will then
wake them from nap mode and use them for running guest code (while
they are still offline).  To wake the secondary threads, we send
them an IPI using a new xics_wake_cpu() function, implemented in
arch/powerpc/sysdev/xics/icp-native.c.  In other words, at this stage
we assume that the platform has a XICS interrupt controller and
we are using icp-native.c to drive it.  Since the woken thread will
need to acknowledge and clear the IPI, we also export the base
physical address of the XICS registers using kvmppc_set_xics_phys()
for use in the low-level KVM book3s code.

When a vcpu is created, it is assigned to a virtual CPU core.
The vcore number is obtained by dividing the vcpu number by the
number of threads per core in the host.  This number is exported
to userspace via the KVM_CAP_PPC_SMT capability.  If qemu wishes
to run the guest in single-threaded mode, it should make all vcpu
numbers be multiples of the number of threads per core.

We distinguish three states of a vcpu: runnable (i.e., ready to execute
the guest), blocked (that is, idle), and busy in host.  We currently
implement a policy that the vcore can run only when all its threads
are runnable or blocked.  This way, if a vcpu needs to execute elsewhere
in the kernel or in qemu, it can do so without being starved of CPU
by the other vcpus.

When a vcore starts to run, it executes in the context of one of the
vcpu threads.  The other vcpu threads all go to sleep and stay asleep
until something happens requiring the vcpu thread to return to qemu,
or to wake up to run the vcore (this can happen when another vcpu
thread goes from busy in host state to blocked).

It can happen that a vcpu goes from blocked to runnable state (e.g.
because of an interrupt), and the vcore it belongs to is already
running.  In that case it can start to run immediately as long as
the none of the vcpus in the vcore have started to exit the guest.
We send the next free thread in the vcore an IPI to get it to start
to execute the guest.  It synchronizes with the other threads via
the vcore->entry_exit_count field to make sure that it doesn't go
into the guest if the other vcpus are exiting by the time that it
is ready to actually enter the guest.

Note that there is no fixed relationship between the hardware thread
number and the vcpu number.  Hardware threads are assigned to vcpus
as they become runnable, so we will always use the lower-numbered
hardware threads in preference to higher-numbered threads if not all
the vcpus in the vcore are runnable, regardless of which vcpus are
runnable.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>

This improves I/O performance for guests using the PAPR
paravirtualization interface by making the H_PUT_TCE hcall faster, by
implementing it in real mode.  H_PUT_TCE is used for updating virtual
IOMMU tables, and is used both for virtual I/O and for real I/O in the
PAPR interface.

Since this moves the IOMMU tables into the kernel, we define a new
KVM_CREATE_SPAPR_TCE ioctl to allow qemu to create the tables.  The
ioctl returns a file descriptor which can be used to mmap the newly
created table.  The qemu driver models use them in the same way as
userspace managed tables, but they can be updated directly by the
guest with a real-mode H_PUT_TCE implementation, reducing the number
of host/guest context switches during guest IO.

There are certain circumstances where it is useful for userland qemu
to write to the TCE table even if the kernel H_PUT_TCE path is used
most of the time.  Specifically, allowing this will avoid awkwardness
when we need to reset the table.  More importantly, we will in the
future need to write the table in order to restore its state after a
checkpoint resume or migration.
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>

This adds the infrastructure for handling PAPR hcalls in the kernel,
either early in the guest exit path while we are still in real mode,
or later once the MMU has been turned back on and we are in the full
kernel context.  The advantage of handling hcalls in real mode if
possible is that we avoid two partition switches -- and this will
become more important when we support SMT4 guests, since a partition
switch means we have to pull all of the threads in the core out of
the guest.  The disadvantage is that we can only access the kernel
linear mapping, not anything vmalloced or ioremapped, since the MMU
is off.

This also adds code to handle the following hcalls in real mode:

H_ENTER       Add an HPTE to the hashed page table
H_REMOVE      Remove an HPTE from the hashed page table
H_READ        Read HPTEs from the hashed page table
H_PROTECT     Change the protection bits in an HPTE
H_BULK_REMOVE Remove up to 4 HPTEs from the hashed page table
H_SET_DABR    Set the data address breakpoint register

Plus code to handle the following hcalls in the kernel:

H_CEDE        Idle the vcpu until an interrupt or H_PROD hcall arrives
H_PROD        Wake up a ceded vcpu
H_REGISTER_VPA Register a virtual processor area (VPA)

The code that runs in real mode has to be in the base kernel, not in
the module, if KVM is compiled as a module.  The real-mode code can
only access the kernel linear mapping, not vmalloc or ioremap space.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>

This adds support for KVM running on 64-bit Book 3S processors,
specifically POWER7, in hypervisor mode.  Using hypervisor mode means
that the guest can use the processor's supervisor mode.  That means
that the guest can execute privileged instructions and access privileged
registers itself without trapping to the host.  This gives excellent
performance, but does mean that KVM cannot emulate a processor
architecture other than the one that the hardware implements.

This code assumes that the guest is running paravirtualized using the
PAPR (Power Architecture Platform Requirements) interface, which is the
interface that IBM's PowerVM hypervisor uses.  That means that existing
Linux distributions that run on IBM pSeries machines will also run
under KVM without modification.  In order to communicate the PAPR
hypercalls to qemu, this adds a new KVM_EXIT_PAPR_HCALL exit code
to include/linux/kvm.h.

Currently the choice between book3s_hv support and book3s_pr support
(i.e. the existing code, which runs the guest in user mode) has to be
made at kernel configuration time, so a given kernel binary can only
do one or the other.

This new book3s_hv code doesn't support MMIO emulation at present.
Since we are running paravirtualized guests, this isn't a serious
restriction.

With the guest running in supervisor mode, most exceptions go straight
to the guest.  We will never get data or instruction storage or segment
interrupts, alignment interrupts, decrementer interrupts, program
interrupts, single-step interrupts, etc., coming to the hypervisor from
the guest.  Therefore this introduces a new KVMTEST_NONHV macro for the
exception entry path so that we don't have to do the KVM test on entry
to those exception handlers.

We do however get hypervisor decrementer, hypervisor data storage,
hypervisor instruction storage, and hypervisor emulation assist
interrupts, so we have to handle those.

In hypervisor mode, real-mode accesses can access all of RAM, not just
a limited amount.  Therefore we put all the guest state in the vcpu.arch
and use the shadow_vcpu in the PACA only for temporary scratch space.
We allocate the vcpu with kzalloc rather than vzalloc, and we don't use
anything in the kvmppc_vcpu_book3s struct, so we don't allocate it.
We don't have a shared page with the guest, but we still need a
kvm_vcpu_arch_shared struct to store the values of various registers,
so we include one in the vcpu_arch struct.

The POWER7 processor has a restriction that all threads in a core have
to be in the same partition.  MMU-on kernel code counts as a partition
(partition 0), so we have to do a partition switch on every entry to and
exit from the guest.  At present we require the host and guest to run
in single-thread mode because of this hardware restriction.

This code allocates a hashed page table for the guest and initializes
it with HPTEs for the guest's Virtual Real Memory Area (VRMA).  We
require that the guest memory is allocated using 16MB huge pages, in
order to simplify the low-level memory management.  This also means that
we can get away without tracking paging activity in the host for now,
since huge pages can't be paged or swapped.

This also adds a few new exports needed by the book3s_hv code.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>

Instead of doing the kvm_guest_enter/exit() and local_irq_dis/enable()
calls in powerpc.c, this moves them down into the subarch-specific
book3s_pr.c and booke.c.  This eliminates an extra local_irq_enable()
call in book3s_pr.c, and will be needed for when we do SMT4 guest
support in the book3s hypervisor mode code.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>

This arranges for the top-level arch/powerpc/kvm/powerpc.c file to
pass down some of the calls it gets to the lower-level subarchitecture
specific code.  The lower-level implementations (in booke.c and book3s.c)
are no-ops.  The coming book3s_hv.c will need this.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>

This is a shared page used for paravirtualization.  It is always present
in the guest kernel's effective address space at the address indicated
by the hypercall that enables it.

The physical address specified by the hypercall is not used, as
e500 does not have real mode.
Signed-off-by: NScott Wood <scottwood@freescale.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

Signed-off-by: NScott Wood <scottwood@freescale.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

Linux doesn't use USPRG0 (now renamed VRSAVE in the architecture, even
when Altivec isn't involved), but a guest might.
Signed-off-by: NScott Wood <scottwood@freescale.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

Following dump is observed on host when clearing the exit timing counters

[root@p1021mds kvm]# echo -n 'c' > vm1200_vcpu0_timing
INFO: task echo:1276 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
echo          D 0ff5bf94     0  1276   1190 0x00000000
Call Trace:
[c2157e40] [c0007908] __switch_to+0x9c/0xc4
[c2157e50] [c040293c] schedule+0x1b4/0x3bc
[c2157e90] [c04032dc] __mutex_lock_slowpath+0x74/0xc0
[c2157ec0] [c00369e4] kvmppc_init_timing_stats+0x20/0xb8
[c2157ed0] [c0036b00] kvmppc_exit_timing_write+0x84/0x98
[c2157ef0] [c00b9f90] vfs_write+0xc0/0x16c
[c2157f10] [c00ba284] sys_write+0x4c/0x90
[c2157f40] [c000e320] ret_from_syscall+0x0/0x3c

        The vcpu->mutex is used by kvm_ioctl_* (KVM_RUN etc) and same was
used when clearing the stats (in kvmppc_init_timing_stats()). What happens
is that when the guest is idle then it held the vcpu->mutx. While the
exiting timing process waits for guest to release the vcpu->mutex and
a hang state is reached.

        Now using seprate lock for exit timing stats.
Signed-off-by: NBharat Bhushan <Bharat.Bhushan@freescale.com>
Acked-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

IA64 support forces us to abstract the allocation of the kvm structure.
But instead of mixing this up with arch-specific initialization and
doing the same on destruction, split both steps. This allows to move
generic destruction calls into generic code.

It also fixes error clean-up on failures of kvm_create_vm for IA64.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Structure kvm_ppc_pvinfo is copied to userland with flags and
pad fields unitialized.  It leads to leaking of contents of
kernel stack memory.
Signed-off-by: NVasiliy Kulikov <segooon@gmail.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Now that we have all the level interrupt magic in place, let's
expose the capability to user space, so it can make use of it!
Signed-off-by: NAlexander Graf <agraf@suse.de>

Now that the actual mtsr doesn't do anything anymore, we can move the sr
contents over to the shared page, so a guest can directly read and write
its sr contents from guest context.
Signed-off-by: NAlexander Graf <agraf@suse.de>

We will soon add SR PV support to the shared page, so we need some
infrastructure that allows the guest to query for features KVM exports.

This patch adds a second return value to the magic mapping that
indicated to the guest which features are available.
Signed-off-by: NAlexander Graf <agraf@suse.de>

We need to tell the guest the opcodes that make up a hypercall through
interfaces that are controlled by userspace. So we need to add a call
for userspace to allow it to query those opcodes so it can pass them
on.

This is required because the hypercall opcodes can change based on
the hypervisor conditions. If we're running in hardware accelerated
hypervisor mode, a hypercall looks different from when we're running
without hardware acceleration.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Now that we have the shared page in place and the MMU code knows about
the magic page, we can expose that capability to the guest!
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

To communicate with KVM directly we need to plumb some sort of interface
between the guest and KVM. Usually those interfaces use hypercalls.

This hypercall implementation is described in the last patch of the series
in a special documentation file. Please read that for further information.

This patch implements stubs to handle KVM PPC hypercalls on the host and
guest side alike.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

One of the most obvious registers to share with the guest directly is the
MSR. The MSR contains the "interrupts enabled" flag which the guest has to
toggle in critical sections.

So in order to bring the overhead of interrupt en- and disabling down, let's
put msr into the shared page. Keep in mind that even though you can fully read
its contents, writing to it doesn't always update all state. There are a few
safe fields that don't require hypervisor interaction. See the documentation
for a list of MSR bits that are safe to be set from inside the guest.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

As advertised in feature-removal-schedule.txt.  Equivalent support is provided
by overlapping memory regions.
Signed-off-by: NAvi Kivity <avi@redhat.com>

Fix compile warning:
  CC [M]  arch/powerpc/kvm/powerpc.o
  arch/powerpc/kvm/powerpc.c: In function 'kvm_arch_vcpu_ioctl_run':
  arch/powerpc/kvm/powerpc.c:290: warning: 'gpr' may be used uninitialized in this function
  arch/powerpc/kvm/powerpc.c:290: note: 'gpr' was declared here
Signed-off-by: NDenis Kirjanov <dkirjanov@kernel.org>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Now that all arch specific ioctls have centralized locking, it is easy to
move it to the central dispatcher.
Signed-off-by: NAvi Kivity <avi@redhat.com>

Signed-off-by: NAvi Kivity <avi@redhat.com>

All vcpu ioctls need to be locked, so instead of locking each one specifically
we lock at the generic dispatcher.

This patch only updates generic ioctls and leaves arch specific ioctls alone.
Signed-off-by: NAvi Kivity <avi@redhat.com>

We already have some inline fuctions we use to access vcpu or svcpu structs,
depending on whether we're on booke or book3s. Since we just put a few more
registers into the svcpu, we also need to make sure the respective callbacks
are available and get used.

So this patch moves direct use of the now in the svcpu struct fields to
inline function calls. While at it, it also moves the definition of those
inline function calls to respective header files for booke and book3s,
greatly improving readability.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

BookE KVM doesn't know about QPRs, so let's not try to access then.

This fixes a build error on BookE KVM.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

MOL uses its own hypercall interface to call back into userspace when
the guest wants to do something.

So let's implement that as an exit reason, specify it with a CAP and
only really use it when userspace wants us to.

The only user of it so far is MOL.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Some times we don't want all capabilities to be available to all
our vcpus. One example for that is the OSI interface, implemented
in the next patch.

In order to have a generic mechanism in how to enable capabilities
individually, this patch introduces a new ioctl that can be used
for this purpose. That way features we don't want in all guests or
userspace configurations can just not be enabled and we're good.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Userspace can tell us that it wants to trigger an interrupt. But
so far it can't tell us that it wants to stop triggering one.

So let's interpret the parameter to the ioctl that we have anyways
to tell us if we want to raise or lower the interrupt line.
Signed-off-by: NAlexander Graf <agraf@suse.de>

v2 -> v3:

 - Add CAP for unset irq
Signed-off-by: NAvi Kivity <avi@redhat.com>

If fail to create the vcpu, we should not create the debugfs
for it.
Signed-off-by: NWei Yongjun <yjwei@cn.fujitsu.com>
Acked-by: NAlexander Graf <agraf@suse.de>
Cc: stable@kernel.org
Signed-off-by: NAvi Kivity <avi@redhat.com>

When we destory a vcpu, we should also make sure to kill all pending
timers that could still be up. When not doing this, hrtimers might
dereference null pointers trying to call our code.

This patch fixes spontanious kernel panics seen after closing VMs.
Signed-off-by: NAlexander Graf <alex@csgraf.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

We need to tell userspace that we can emulate paired single instructions.
So let's add a capability export.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

The guest I was trying to get to run uses the LHA and LHAU instructions.
Those instructions basically do a load, but also sign extend the result.

Since we need to fill our registers by hand when doing MMIO, we also need
to sign extend manually.

This patch implements sign extended MMIO and the LHA(U) instructions.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Right now MMIO access can only happen for GPRs and is at most 32 bit wide.
That's actually enough for almost all types of hardware out there.

Unfortunately, the guest I was using used FPU writes to MMIO regions, so
it ended up writing 64 bit MMIOs using FPRs and QPRs.

So let's add code to handle those odd cases too.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: NTejun Heo <tj@kernel.org>
Guess-its-ok-by: NChristoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

cleanup_srcu_struct on VM destruction remains broken:

BUG: unable to handle kernel paging request at ffffffffffffffff
IP: [<ffffffff802533d2>] srcu_read_lock+0x16/0x21
RIP: 0010:[<ffffffff802533d2>]  [<ffffffff802533d2>] srcu_read_lock+0x16/0x21
Call Trace:
 [<ffffffffa05354c4>] kvm_arch_vcpu_uninit+0x1b/0x48 [kvm]
 [<ffffffffa05339c6>] kvm_vcpu_uninit+0x9/0x15 [kvm]
 [<ffffffffa0569f7d>] vmx_free_vcpu+0x7f/0x8f [kvm_intel]
 [<ffffffffa05357b5>] kvm_arch_destroy_vm+0x78/0x111 [kvm]
 [<ffffffffa053315b>] kvm_put_kvm+0xd4/0xfe [kvm]

Move it to kvm_arch_destroy_vm.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Reported-by: NJan Kiszka <jan.kiszka@siemens.com>

All code in PPC KVM currently accesses gprs in the vcpu struct directly.

While there's nothing wrong with that wrt the current way gprs are stored
and loaded, it doesn't suffice for the PACA acceleration that will follow
in this patchset.

So let's just create little wrapper inline functions that we call whenever
a GPR needs to be read from or written to. The compiled code shouldn't really
change at all for now.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Required for SRCU convertion later.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Currently userspace has no chance to find out which virtual address space we're
in and resolve addresses. While that is a big problem for migration, it's also
unpleasent when debugging, as gdb and the monitor don't work on virtual
addresses.

This patch exports enough of the MMU segment state to userspace to make
debugging work and thus also includes the groundwork for migration.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

X86 CPUs need to have some magic happening to enable the virtualization
extensions on them. This magic can result in unpleasant results for
users, like blocking other VMMs from working (vmx) or using invalid TLB
entries (svm).

Currently KVM activates virtualization when the respective kernel module
is loaded. This blocks us from autoloading KVM modules without breaking
other VMMs.

To circumvent this problem at least a bit, this patch introduces on
demand activation of virtualization. This means, that instead
virtualization is enabled on creation of the first virtual machine
and disabled on destruction of the last one.

So using this, KVM can be easily autoloaded, while keeping other
hypervisors usable.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>