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  1. 02 3月, 2017 1 次提交
  3. 17 2月, 2017 2 次提交
    • P
      KVM: race-free exit from KVM_RUN without POSIX signals · 460df4c1
      由 Paolo Bonzini 提交于 
      The purpose of the KVM_SET_SIGNAL_MASK API is to let userspace "kick"
a VCPU out of KVM_RUN through a POSIX signal.  A signal is attached
to a dummy signal handler; by blocking the signal outside KVM_RUN and
unblocking it inside, this possible race is closed:

          VCPU thread                     service thread
   --------------------------------------------------------------
        check flag
                                          set flag
                                          raise signal
        (signal handler does nothing)
        KVM_RUN

However, one issue with KVM_SET_SIGNAL_MASK is that it has to take
tsk->sighand->siglock on every KVM_RUN.  This lock is often on a
remote NUMA node, because it is on the node of a thread's creator.
Taking this lock can be very expensive if there are many userspace
exits (as is the case for SMP Windows VMs without Hyper-V reference
time counter).

As an alternative, we can put the flag directly in kvm_run so that
KVM can see it:

          VCPU thread                     service thread
   --------------------------------------------------------------
                                          raise signal
        signal handler
          set run->immediate_exit
        KVM_RUN
          check run->immediate_exit
Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com>
Reviewed-by: NDavid Hildenbrand <david@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      460df4c1
    • P
      s390: Audit and remove any remaining unnecessary uses of module.h · d3217967
      由 Paul Gortmaker 提交于 
      Historically a lot of these existed because we did not have
a distinction between what was modular code and what was providing
support to modules via EXPORT_SYMBOL and friends.  That changed
when we forked out support for the latter into the export.h file.

This means we should be able to reduce the usage of module.h
in code that is obj-y Makefile or bool Kconfig.  The advantage
in doing so is that module.h itself sources about 15 other headers;
adding significantly to what we feed cpp, and it can obscure what
headers we are effectively using.

Since module.h was the source for init.h (for __init) and for
export.h (for EXPORT_SYMBOL) we consider each change instance
for the presence of either and replace as needed.  An instance
where module_param was used without moduleparam.h was also fixed,
as well as implicit use of ptrace.h and string.h headers.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
      d3217967
  5. 06 2月, 2017 1 次提交
  7. 30 1月, 2017 6 次提交
  9. 20 1月, 2017 1 次提交
    • C
      KVM: s390: do not expose random data via facility bitmap · 04478197
      由 Christian Borntraeger 提交于 
      kvm_s390_get_machine() populates the facility bitmap by copying bytes
from the host results that are stored in a 256 byte array in the prefix
page. The KVM code does use the size of the target buffer (2k), thus
copying and exposing unrelated kernel memory (mostly machine check
related logout data).

Let's use the size of the source buffer instead.  This is ok, as the
target buffer will always be greater or equal than the source buffer as
the KVM internal buffers (and thus S390_ARCH_FAC_LIST_SIZE_BYTE) cover
the maximum possible size that is allowed by STFLE, which is 256
doublewords. All structures are zero allocated so we can leave bytes
256-2047 unchanged.

Add a similar fix for kvm_arch_init_vm().
Reported-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
[found with smatch]
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
CC: stable@vger.kernel.org
Acked-by: NCornelia Huck <cornelia.huck@de.ibm.com>
      04478197
  11. 23 11月, 2016 2 次提交
    • C
      KVM: s390: handle floating point registers in the run ioctl not in vcpu_put/load · e1788bb9
      由 Christian Borntraeger 提交于 
      Right now we switch the host fprs/vrs in kvm_arch_vcpu_load and switch
back in kvm_arch_vcpu_put. This process is already optimized
since commit 9977e886 ("s390/kernel: lazy restore fpu registers")
avoiding double save/restores on schedule. We still reload the pointers
and test the guest fpc on each context switch, though.

We can minimize the cost of vcpu_load/put by doing the test in the
VCPU_RUN ioctl itself. As most VCPU threads almost never exit to
userspace in the common fast path, this allows to avoid this overhead
for the common case (eventfd driven I/O, all exits including sleep
handled in the kernel) - making kvm_arch_vcpu_load/put basically
disappear in perf top.

Also adapt the fpu get/set ioctls.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
      e1788bb9
    • C
      KVM: s390: handle access registers in the run ioctl not in vcpu_put/load · 31d8b8d4
      由 Christian Borntraeger 提交于 
      Right now we save the host access registers in kvm_arch_vcpu_load
and load them in kvm_arch_vcpu_put. Vice versa for the guest access
registers. On schedule this means, that we load/save access registers
multiple times.

e.g. VCPU_RUN with just one reschedule and then return does

[from user space via VCPU_RUN]
- save the host registers in kvm_arch_vcpu_load (via ioctl)
- load the guest registers in kvm_arch_vcpu_load (via ioctl)
- do guest stuff
- decide to schedule/sleep
- save the guest registers in kvm_arch_vcpu_put (via sched)
- load the host registers in kvm_arch_vcpu_put (via sched)
- save the host registers in switch_to (via sched)
- schedule
- return
- load the host registers in switch_to (via sched)
- save the host registers in kvm_arch_vcpu_load (via sched)
- load the guest registers in kvm_arch_vcpu_load (via sched)
- do guest stuff
- decide to go to userspace
- save the guest registers in kvm_arch_vcpu_put (via ioctl)
- load the host registers in kvm_arch_vcpu_put (via ioctl)
[back to user space]

As the kernel does not use access registers, we can avoid
this reloading and simply piggy back on switch_to (let it save
the guest values instead of host values in thread.acrs) by
moving the host/guest switch into the VCPU_RUN ioctl function.
We now do

[from user space via VCPU_RUN]
- save the host registers in kvm_arch_vcpu_ioctl_run
- load the guest registers in kvm_arch_vcpu_ioctl_run
- do guest stuff
- decide to schedule/sleep
- save the guest registers in switch_to
- schedule
- return
- load the guest registers in switch_to (via sched)
- do guest stuff
- decide to go to userspace
- save the guest registers in kvm_arch_vcpu_ioctl_run
- load the host registers in kvm_arch_vcpu_ioctl_run

This seems to save about 10% of the vcpu_put/load functions
according to perf.

As vcpu_load no longer switches the acrs, We can also loading
the acrs in kvm_arch_vcpu_ioctl_set_sregs.
Suggested-by: NFan Zhang <zhangfan@linux.vnet.ibm.com>
Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
      31d8b8d4
  13. 16 9月, 2016 1 次提交
  15. 08 9月, 2016 3 次提交
  17. 29 8月, 2016 1 次提交
  19. 26 8月, 2016 1 次提交
  21. 25 8月, 2016 1 次提交
  23. 12 8月, 2016 2 次提交
  25. 18 7月, 2016 1 次提交
  27. 01 7月, 2016 1 次提交
  29. 21 6月, 2016 11 次提交
  31. 20 6月, 2016 5 次提交