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  1. 22 Aug, 2015 6 commits
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Implement dynamic micro-threading on POWER8 · b4deba5c
      Paul Mackerras authored 
      This builds on the ability to run more than one vcore on a physical
core by using the micro-threading (split-core) modes of the POWER8
chip.  Previously, only vcores from the same VM could be run together,
and (on POWER8) only if they had just one thread per core.  With the
ability to split the core on guest entry and unsplit it on guest exit,
we can run up to 8 vcpu threads from up to 4 different VMs, and we can
run multiple vcores with 2 or 4 vcpus per vcore.

Dynamic micro-threading is only available if the static configuration
of the cores is whole-core mode (unsplit), and only on POWER8.

To manage this, we introduce a new kvm_split_mode struct which is
shared across all of the subcores in the core, with a pointer in the
paca on each thread.  In addition we extend the core_info struct to
have information on each subcore.  When deciding whether to add a
vcore to the set already on the core, we now have two possibilities:
(a) piggyback the vcore onto an existing subcore, or (b) start a new
subcore.

Currently, when any vcpu needs to exit the guest and switch to host
virtual mode, we interrupt all the threads in all subcores and switch
the core back to whole-core mode.  It may be possible in future to
allow some of the subcores to keep executing in the guest while
subcore 0 switches to the host, but that is not implemented in this
patch.

This adds a module parameter called dynamic_mt_modes which controls
which micro-threading (split-core) modes the code will consider, as a
bitmap.  In other words, if it is 0, no micro-threading mode is
considered; if it is 2, only 2-way micro-threading is considered; if
it is 4, only 4-way, and if it is 6, both 2-way and 4-way
micro-threading mode will be considered.  The default is 6.

With this, we now have secondary threads which are the primary thread
for their subcore and therefore need to do the MMU switch.  These
threads will need to be started even if they have no vcpu to run, so
we use the vcore pointer in the PACA rather than the vcpu pointer to
trigger them.

It is now possible for thread 0 to find that an exit has been
requested before it gets to switch the subcore state to the guest.  In
that case we haven't added the guest's timebase offset to the
timebase, so we need to be careful not to subtract the offset in the
guest exit path.  In fact we just skip the whole path that switches
back to host context, since we haven't switched to the guest context.
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
      b4deba5c
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Make use of unused threads when running guests · ec257165
      Paul Mackerras authored 
      When running a virtual core of a guest that is configured with fewer
threads per core than the physical cores have, the extra physical
threads are currently unused.  This makes it possible to use them to
run one or more other virtual cores from the same guest when certain
conditions are met.  This applies on POWER7, and on POWER8 to guests
with one thread per virtual core.  (It doesn't apply to POWER8 guests
with multiple threads per vcore because they require a 1-1 virtual to
physical thread mapping in order to be able to use msgsndp and the
TIR.)

The idea is that we maintain a list of preempted vcores for each
physical cpu (i.e. each core, since the host runs single-threaded).
Then, when a vcore is about to run, it checks to see if there are
any vcores on the list for its physical cpu that could be
piggybacked onto this vcore's execution.  If so, those additional
vcores are put into state VCORE_PIGGYBACK and their runnable VCPU
threads are started as well as the original vcore, which is called
the master vcore.

After the vcores have exited the guest, the extra ones are put back
onto the preempted list if any of their VCPUs are still runnable and
not idle.

This means that vcpu->arch.ptid is no longer necessarily the same as
the physical thread that the vcpu runs on.  In order to make it easier
for code that wants to send an IPI to know which CPU to target, we
now store that in a new field in struct vcpu_arch, called thread_cpu.
Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Tested-by: default avatarLaurent Vivier <lvivier@redhat.com>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
      ec257165
    • Tudor Laurentiu's avatar
      KVM: PPC: add missing pt_regs initialization · 845ac985
      Tudor Laurentiu authored 
      On this switch branch the regs initialization
doesn't happen so add it.
This was found with the help of a static
code analysis tool.
Signed-off-by: default avatarLaurentiu Tudor <Laurentiu.Tudor@freescale.com>
Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
      845ac985
    • Thomas Huth's avatar
      KVM: PPC: Fix warnings from sparse · 5358a963
      Thomas Huth authored 
      When compiling the KVM code for POWER with "make C=1", sparse
complains about functions missing proper prototypes and a 64-bit
constant missing the ULL prefix. Let's fix this by making the
functions static or by including the proper header with the
prototypes, and by appending a ULL prefix to the constant
PPC_MPPE_ADDRESS_MASK.
Signed-off-by: default avatarThomas Huth <thuth@redhat.com>
Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
      5358a963
    • Thomas Huth's avatar
      KVM: PPC: Remove PPC970 from KVM_BOOK3S_64_HV text in Kconfig · 129fd423
      Thomas Huth authored 
      Since the PPC970 support has been removed from the kvm-hv kernel
module recently, we should also reflect this change in the help
text of the corresponding Kconfig option.
Signed-off-by: default avatarThomas Huth <thuth@redhat.com>
Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
      129fd423
    • Tudor Laurentiu's avatar
      KVM: PPC: fix suspicious use of conditional operator · f5ffe330
      Tudor Laurentiu authored 
      This was signaled by a static code analysis tool.
Signed-off-by: default avatarLaurentiu Tudor <Laurentiu.Tudor@freescale.com>
Reviewed-by: default avatarScott Wood <scottwood@freescale.com>
Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
      f5ffe330
  3. 14 Aug, 2015 1 commit
  5. 13 Aug, 2015 1 commit
    • Paolo Bonzini's avatar
      Merge tag 'kvm-s390-next-20150812' of... · ae6c0aa6
      Paolo Bonzini authored 
      Merge tag 'kvm-s390-next-20150812' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

KVM: s390: fix and feature for kvm/next (4.3)

1. error handling for irq routes
2. Gracefully handle STP time changes
   s390 supports a protocol for syncing different systems via the stp
   protocol that will steer the TOD clocks to keep all participating
   clocks below the round trip time between the system. In case of
   specific out of sync event Linux can opt-in to accept sync checks.
   This will result in non-monotonic jumps of the TOD clock, which
   Linux will correct via time offsets to keep the wall clock time
   monotonic. Now: KVM guests also base their time on the host TOD,
   so we need to fixup the offset for them as well.
      ae6c0aa6
  7. 11 Aug, 2015 2 commits
  9. 07 Aug, 2015 1 commit
  11. 05 Aug, 2015 10 commits
  13. 04 Aug, 2015 1 commit
  15. 30 Jul, 2015 2 commits
  17. 29 Jul, 2015 16 commits
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