linux_dsm_epyc7002/arch/x86
Andrey Smetanin 481d2bcc84 kvm/x86: Remove Hyper-V SynIC timer stopping
It's possible that guest send us Hyper-V EOM at the middle
of Hyper-V SynIC timer running, so we start processing of Hyper-V
SynIC timers in vcpu context and stop the Hyper-V SynIC timer
unconditionally:

    host                                       guest
    ------------------------------------------------------------------------------
                                           start periodic stimer
    start periodic timer
    timer expires after 15ms
    send expiration message into guest
    restart periodic timer
    timer expires again after 15 ms
    msg slot is still not cleared so
    setup ->msg_pending
(1) restart periodic timer
                                           process timer msg and clear slot
                                           ->msg_pending was set:
                                               send EOM into host
    received EOM
      kvm_make_request(KVM_REQ_HV_STIMER)

    kvm_hv_process_stimers():
        ...
        stimer_stop()
        if (time_now >= stimer->exp_time)
                stimer_expiration(stimer);

Because the timer was rearmed at (1), time_now < stimer->exp_time
and stimer_expiration is not called.  The timer then never fires.

The patch fixes such situation by not stopping Hyper-V SynIC timer
at all, because it's safe to restart it without stop in vcpu context
and timer callback always returns HRTIMER_NORESTART.

Signed-off-by: Andrey Smetanin <asmetanin@virtuozzo.com>
CC: Gleb Natapov <gleb@kernel.org>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Roman Kagan <rkagan@virtuozzo.com>
CC: Denis V. Lunev <den@openvz.org>
CC: qemu-devel@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-12-16 18:51:22 +01:00
..
boot kasan: move KASAN_SANITIZE in arch/x86/boot/Makefile 2015-11-05 19:34:48 -08:00
configs Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux 2015-09-04 15:49:32 -07:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2015-11-04 09:11:12 -08:00
entry mm: mlock: add new mlock system call 2015-11-05 19:34:48 -08:00
ia32 Merge branch 'x86-headers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 21:05:40 -08:00
include kvm/x86: Hyper-V SynIC timers 2015-12-16 18:49:45 +01:00
kernel Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-22 12:00:12 -08:00
kvm kvm/x86: Remove Hyper-V SynIC timer stopping 2015-12-16 18:51:22 +01:00
lguest genirq: Remove irq argument from irq flow handlers 2015-09-16 15:47:51 +02:00
lib Linux 4.3-rc1 2015-09-13 11:25:35 +02:00
math-emu Merge branch 'x86-headers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 21:05:40 -08:00
mm Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-22 12:00:12 -08:00
net ebpf: migrate bpf_prog's flags to bitfield 2015-10-03 05:02:39 -07:00
oprofile
pci PCI changes for the v4.4 merge window: 2015-11-06 11:29:53 -08:00
platform Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 21:33:18 -08:00
power x86/ldt: Make modify_ldt synchronous 2015-07-31 10:23:23 +02:00
purgatory
ras x86/ras/mce_amd_inj: Inject bank 4 errors on the NBC 2015-10-12 16:15:48 +02:00
realmode
tools
um Merge branch 'for-linus-4.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml 2015-11-10 16:33:37 -08:00
video
xen xen: features for 4.4-rc0 2015-11-04 17:32:42 -08:00
.gitignore
Kbuild x86/asm/entry, x86/vdso: Move the vDSO code to arch/x86/entry/vdso/ 2015-06-03 18:51:37 +02:00
Kconfig Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 18:59:10 -08:00
Kconfig.cpu x86/Kconfig/cpus: Fix/complete CPU type help texts 2015-10-21 11:12:56 +02:00
Kconfig.debug x86: don't make DEBUG_WX default to 'y' even with DEBUG_RODATA 2015-11-06 09:12:41 -08:00
Makefile Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2015-11-04 09:11:12 -08:00
Makefile_32.cpu
Makefile.um