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  1. 02 12月, 2012 1 次提交
  3. 01 12月, 2012 2 次提交
    • W
      KVM: x86: Emulate IA32_TSC_ADJUST MSR · ba904635
      由 Will Auld 提交于 
      CPUID.7.0.EBX[1]=1 indicates IA32_TSC_ADJUST MSR 0x3b is supported

Basic design is to emulate the MSR by allowing reads and writes to a guest
vcpu specific location to store the value of the emulated MSR while adding
the value to the vmcs tsc_offset. In this way the IA32_TSC_ADJUST value will
be included in all reads to the TSC MSR whether through rdmsr or rdtsc. This
is of course as long as the "use TSC counter offsetting" VM-execution control
is enabled as well as the IA32_TSC_ADJUST control.

However, because hardware will only return the TSC + IA32_TSC_ADJUST +
vmsc tsc_offset for a guest process when it does and rdtsc (with the correct
settings) the value of our virtualized IA32_TSC_ADJUST must be stored in one
of these three locations. The argument against storing it in the actual MSR
is performance. This is likely to be seldom used while the save/restore is
required on every transition. IA32_TSC_ADJUST was created as a way to solve
some issues with writing TSC itself so that is not an option either.

The remaining option, defined above as our solution has the problem of
returning incorrect vmcs tsc_offset values (unless we intercept and fix, not
done here) as mentioned above. However, more problematic is that storing the
data in vmcs tsc_offset will have a different semantic effect on the system
than does using the actual MSR. This is illustrated in the following example:

The hypervisor set the IA32_TSC_ADJUST, then the guest sets it and a guest
process performs a rdtsc. In this case the guest process will get
TSC + IA32_TSC_ADJUST_hyperviser + vmsc tsc_offset including
IA32_TSC_ADJUST_guest. While the total system semantics changed the semantics
as seen by the guest do not and hence this will not cause a problem.
Signed-off-by: NWill Auld <will.auld@intel.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
      ba904635
    • W
      KVM: x86: Add code to track call origin for msr assignment · 8fe8ab46
      由 Will Auld 提交于 
      In order to track who initiated the call (host or guest) to modify an msr
value I have changed function call parameters along the call path. The
specific change is to add a struct pointer parameter that points to (index,
data, caller) information rather than having this information passed as
individual parameters.

The initial use for this capability is for updating the IA32_TSC_ADJUST msr
while setting the tsc value. It is anticipated that this capability is
useful for other tasks.
Signed-off-by: NWill Auld <will.auld@intel.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
      8fe8ab46
  5. 30 11月, 2012 2 次提交
  7. 29 11月, 2012 2 次提交
  9. 28 11月, 2012 18 次提交
  11. 14 11月, 2012 3 次提交
  13. 01 11月, 2012 2 次提交
    • M
      Merge branch 'for-queue' of https://github.com/agraf/linux-2.6 into queue · f026399f
      由 Marcelo Tosatti 提交于 
      * 'for-queue' of https://github.com/agraf/linux-2.6:
  PPC: ePAPR: Convert hcall header to uapi (round 2)
  KVM: PPC: Book3S HV: Fix thinko in try_lock_hpte()
  KVM: PPC: Book3S HV: Allow DTL to be set to address 0, length 0
  KVM: PPC: Book3S HV: Fix accounting of stolen time
  KVM: PPC: Book3S HV: Run virtual core whenever any vcpus in it can run
  KVM: PPC: Book3S HV: Fixes for late-joining threads
  KVM: PPC: Book3s HV: Don't access runnable threads list without vcore lock
  KVM: PPC: Book3S HV: Fix some races in starting secondary threads
  KVM: PPC: Book3S HV: Allow KVM guests to stop secondary threads coming online
  PPC: ePAPR: Convert header to uapi
  KVM: PPC: Move mtspr/mfspr emulation into own functions
  KVM: Documentation: Fix reentry-to-be-consistent paragraph
  KVM: PPC: 44x: fix DCR read/write
      f026399f
    • J
      KVM: SVM: update MAINTAINERS entry · 7de609c8
      由 Joerg Roedel 提交于 
      I have no access to my AMD email address anymore. Update
entry in MAINTAINERS to the new address.

Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NJoerg Roedel <joro@8bytes.org>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
      7de609c8
  15. 31 10月, 2012 2 次提交
  17. 30 10月, 2012 8 次提交
    • P
      KVM: PPC: Book3S HV: Fix thinko in try_lock_hpte() · 8b5869ad
      由 Paul Mackerras 提交于 
      This fixes an error in the inline asm in try_lock_hpte() where we
were erroneously using a register number as an immediate operand.
The bug only affects an error path, and in fact the code will still
work as long as the compiler chooses some register other than r0
for the "bits" variable.  Nevertheless it should still be fixed.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>
      8b5869ad
    • P
      KVM: PPC: Book3S HV: Allow DTL to be set to address 0, length 0 · 9f8c8c78
      由 Paul Mackerras 提交于 
      Commit 55b665b0 ("KVM: PPC: Book3S HV: Provide a way for userspace
to get/set per-vCPU areas") includes a check on the length of the
dispatch trace log (DTL) to make sure the buffer is at least one entry
long.  This is appropriate when registering a buffer, but the
interface also allows for any existing buffer to be unregistered by
specifying a zero address.  In this case the length check is not
appropriate.  This makes the check conditional on the address being
non-zero.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>
      9f8c8c78
    • P
      KVM: PPC: Book3S HV: Fix accounting of stolen time · c7b67670
      由 Paul Mackerras 提交于 
      Currently the code that accounts stolen time tends to overestimate the
stolen time, and will sometimes report more stolen time in a DTL
(dispatch trace log) entry than has elapsed since the last DTL entry.
This can cause guests to underflow the user or system time measured
for some tasks, leading to ridiculous CPU percentages and total runtimes
being reported by top and other utilities.

In addition, the current code was designed for the previous policy where
a vcore would only run when all the vcpus in it were runnable, and so
only counted stolen time on a per-vcore basis.  Now that a vcore can
run while some of the vcpus in it are doing other things in the kernel
(e.g. handling a page fault), we need to count the time when a vcpu task
is preempted while it is not running as part of a vcore as stolen also.

To do this, we bring back the BUSY_IN_HOST vcpu state and extend the
vcpu_load/put functions to count preemption time while the vcpu is
in that state.  Handling the transitions between the RUNNING and
BUSY_IN_HOST states requires checking and updating two variables
(accumulated time stolen and time last preempted), so we add a new
spinlock, vcpu->arch.tbacct_lock.  This protects both the per-vcpu
stolen/preempt-time variables, and the per-vcore variables while this
vcpu is running the vcore.

Finally, we now don't count time spent in userspace as stolen time.
The task could be executing in userspace on behalf of the vcpu, or
it could be preempted, or the vcpu could be genuinely stopped.  Since
we have no way of dividing up the time between these cases, we don't
count any of it as stolen.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>
      c7b67670
    • P
      KVM: PPC: Book3S HV: Run virtual core whenever any vcpus in it can run · 8455d79e
      由 Paul Mackerras 提交于 
      Currently the Book3S HV code implements a policy on multi-threaded
processors (i.e. POWER7) that requires all of the active vcpus in a
virtual core to be ready to run before we run the virtual core.
However, that causes problems on reset, because reset stops all vcpus
except vcpu 0, and can also reduce throughput since all four threads
in a virtual core have to wait whenever any one of them hits a
hypervisor page fault.

This relaxes the policy, allowing the virtual core to run as soon as
any vcpu in it is runnable.  With this, the KVMPPC_VCPU_STOPPED state
and the KVMPPC_VCPU_BUSY_IN_HOST state have been combined into a single
KVMPPC_VCPU_NOTREADY state, since we no longer need to distinguish
between them.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>
      8455d79e
    • P
      KVM: PPC: Book3S HV: Fixes for late-joining threads · 2f12f034
      由 Paul Mackerras 提交于 
      If a thread in a virtual core becomes runnable while other threads
in the same virtual core are already running in the guest, it is
possible for the latecomer to join the others on the core without
first pulling them all out of the guest.  Currently this only happens
rarely, when a vcpu is first started.  This fixes some bugs and
omissions in the code in this case.

First, we need to check for VPA updates for the latecomer and make
a DTL entry for it.  Secondly, if it comes along while the master
vcpu is doing a VPA update, we don't need to do anything since the
master will pick it up in kvmppc_run_core.  To handle this correctly
we introduce a new vcore state, VCORE_STARTING.  Thirdly, there is
a race because we currently clear the hardware thread's hwthread_req
before waiting to see it get to nap.  A latecomer thread could have
its hwthread_req cleared before it gets to test it, and therefore
never increment the nap_count, leading to messages about wait_for_nap
timeouts.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>
      2f12f034
    • P
      KVM: PPC: Book3s HV: Don't access runnable threads list without vcore lock · 913d3ff9
      由 Paul Mackerras 提交于 
      There were a few places where we were traversing the list of runnable
threads in a virtual core, i.e. vc->runnable_threads, without holding
the vcore spinlock.  This extends the places where we hold the vcore
spinlock to cover everywhere that we traverse that list.

Since we possibly need to sleep inside kvmppc_book3s_hv_page_fault,
this moves the call of it from kvmppc_handle_exit out to
kvmppc_vcpu_run, where we don't hold the vcore lock.

In kvmppc_vcore_blocked, we don't actually need to check whether
all vcpus are ceded and don't have any pending exceptions, since the
caller has already done that.  The caller (kvmppc_run_vcpu) wasn't
actually checking for pending exceptions, so we add that.

The change of if to while in kvmppc_run_vcpu is to make sure that we
never call kvmppc_remove_runnable() when the vcore state is RUNNING or
EXITING.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>
      913d3ff9
    • P
      KVM: PPC: Book3S HV: Fix some races in starting secondary threads · 7b444c67
      由 Paul Mackerras 提交于 
      Subsequent patches implementing in-kernel XICS emulation will make it
possible for IPIs to arrive at secondary threads at arbitrary times.
This fixes some races in how we start the secondary threads, which
if not fixed could lead to occasional crashes of the host kernel.

This makes sure that (a) we have grabbed all the secondary threads,
and verified that they are no longer in the kernel, before we start
any thread, (b) that the secondary thread loads its vcpu pointer
after clearing the IPI that woke it up (so we don't miss a wakeup),
and (c) that the secondary thread clears its vcpu pointer before
incrementing the nap count.  It also removes unnecessary setting
of the vcpu and vcore pointers in the paca in kvmppc_core_vcpu_load.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>
      7b444c67
    • P
      KVM: PPC: Book3S HV: Allow KVM guests to stop secondary threads coming online · 512691d4
      由 Paul Mackerras 提交于 
      When a Book3S HV KVM guest is running, we need the host to be in
single-thread mode, that is, all of the cores (or at least all of
the cores where the KVM guest could run) to be running only one
active hardware thread.  This is because of the hardware restriction
in POWER processors that all of the hardware threads in the core
must be in the same logical partition.  Complying with this restriction
is much easier if, from the host kernel's point of view, only one
hardware thread is active.

This adds two hooks in the SMP hotplug code to allow the KVM code to
make sure that secondary threads (i.e. hardware threads other than
thread 0) cannot come online while any KVM guest exists.  The KVM
code still has to check that any core where it runs a guest has the
secondary threads offline, but having done that check it can now be
sure that they will not come online while the guest is running.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>
      512691d4