forked from Minki/linux
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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| .. | ||
| boot | ||
| common | ||
| configs | ||
| crypto | ||
| firmware | ||
| include | ||
| kernel | ||
| kvm | ||
| lib | ||
| mach-alpine | ||
| mach-artpec | ||
| mach-asm9260 | ||
| mach-aspeed | ||
| mach-at91 | ||
| mach-axxia | ||
| mach-bcm | ||
| mach-berlin | ||
| mach-clps711x | ||
| mach-cns3xxx | ||
| mach-davinci | ||
| mach-digicolor | ||
| mach-dove | ||
| mach-ebsa110 | ||
| mach-efm32 | ||
| mach-ep93xx | ||
| mach-exynos | ||
| mach-footbridge | ||
| mach-gemini | ||
| mach-highbank | ||
| mach-hisi | ||
| mach-imx | ||
| mach-integrator | ||
| mach-iop13xx | ||
| mach-iop32x | ||
| mach-iop33x | ||
| mach-ixp4xx | ||
| mach-keystone | ||
| mach-ks8695 | ||
| mach-lpc18xx | ||
| mach-lpc32xx | ||
| mach-mediatek | ||
| mach-meson | ||
| mach-mmp | ||
| mach-moxart | ||
| mach-mv78xx0 | ||
| mach-mvebu | ||
| mach-mxs | ||
| mach-netx | ||
| mach-nomadik | ||
| mach-nspire | ||
| mach-omap1 | ||
| mach-omap2 | ||
| mach-orion5x | ||
| mach-oxnas | ||
| mach-picoxcell | ||
| mach-prima2 | ||
| mach-pxa | ||
| mach-qcom | ||
| mach-realview | ||
| mach-rockchip | ||
| mach-rpc | ||
| mach-s3c24xx | ||
| mach-s3c64xx | ||
| mach-s5pv210 | ||
| mach-sa1100 | ||
| mach-shmobile | ||
| mach-socfpga | ||
| mach-spear | ||
| mach-sti | ||
| mach-stm32 | ||
| mach-sunxi | ||
| mach-tango | ||
| mach-tegra | ||
| mach-u300 | ||
| mach-uniphier | ||
| mach-ux500 | ||
| mach-versatile | ||
| mach-vexpress | ||
| mach-vt8500 | ||
| mach-w90x900 | ||
| mach-zx | ||
| mach-zynq | ||
| mm | ||
| net | ||
| nwfpe | ||
| oprofile | ||
| plat-iop | ||
| plat-omap | ||
| plat-orion | ||
| plat-pxa | ||
| plat-samsung | ||
| plat-versatile | ||
| probes | ||
| tools | ||
| vdso | ||
| vfp | ||
| xen | ||
| Kconfig | ||
| Kconfig-nommu | ||
| Kconfig.debug | ||
| Makefile | ||