forked from luck/tmp_suning_uos_patched
460df4c1fc
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: Radim Krčmář <rkrcmar@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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| .. | ||
| alchemy | ||
| ar7 | ||
| ath25 | ||
| ath79 | ||
| bcm47xx | ||
| bcm63xx | ||
| bmips | ||
| boot | ||
| cavium-octeon | ||
| cobalt | ||
| configs | ||
| dec | ||
| emma | ||
| fw | ||
| generic | ||
| include | ||
| jazz | ||
| jz4740 | ||
| kernel | ||
| kvm | ||
| lantiq | ||
| lasat | ||
| lib | ||
| loongson32 | ||
| loongson64 | ||
| math-emu | ||
| mm | ||
| mti-malta | ||
| net | ||
| netlogic | ||
| oprofile | ||
| paravirt | ||
| pci | ||
| pic32 | ||
| pistachio | ||
| pmcs-msp71xx | ||
| pnx833x | ||
| power | ||
| ralink | ||
| rb532 | ||
| sgi-ip22 | ||
| sgi-ip27 | ||
| sgi-ip32 | ||
| sibyte | ||
| sni | ||
| txx9 | ||
| vdso | ||
| vr41xx | ||
| xilfpga | ||
| Kbuild | ||
| Kbuild.platforms | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||