linux/virt/kvm
Zachary Amsden ca84d1a24c KVM: x86: Add clock sync request to hardware enable
If there are active VCPUs which are marked as belonging to
a particular hardware CPU, request a clock sync for them when
enabling hardware; the TSC could be desynchronized on a newly
arriving CPU, and we need to recompute guests system time
relative to boot after a suspend event.

This covers both cases.

Note that it is acceptable to take the spinlock, as either
no other tasks will be running and no locks held (BSP after
resume), or other tasks will be guaranteed to drop the lock
relatively quickly (AP on CPU_STARTING).

Noting we now get clock synchronization requests for VCPUs
which are starting up (or restarting), it is tempting to
attempt to remove the arch/x86/kvm/x86.c CPU hot-notifiers
at this time, however it is not correct to do so; they are
required for systems with non-constant TSC as the frequency
may not be known immediately after the processor has started
until the cpufreq driver has had a chance to run and query
the chipset.

Updated: implement better locking semantics for hardware_enable

Removed the hack of dropping and retaking the lock by adding the
semantic that we always hold kvm_lock when hardware_enable is
called.  The one place that doesn't need to worry about it is
resume, as resuming a frozen CPU, the spinlock won't be taken.

Signed-off-by: Zachary Amsden <zamsden@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2010-10-24 10:51:24 +02:00
..
Kconfig KVM: Add KVM_MMIO kconfig item 2010-03-01 12:35:41 -03:00
assigned-dev.c KVM: Fix unused but set warnings 2010-08-01 10:46:29 +03:00
coalesced_mmio.c KVM: Update Red Hat copyrights 2010-08-01 10:35:51 +03:00
coalesced_mmio.h KVM: Simplify coalesced mmio initialization 2010-03-01 12:35:41 -03:00
eventfd.c KVM: fix irqfd assign/deassign race 2010-09-23 11:31:51 -03:00
ioapic.c KVM: Convert mask notifiers to use irqchip/pin instead of gsi 2010-08-02 06:40:39 +03:00
ioapic.h KVM: convert ioapic lock to spinlock 2010-05-13 01:23:55 -03:00
iodev.h KVM: remove in_range from io devices 2009-09-10 08:33:05 +03:00
iommu.c KVM: Use u64 for frame data types 2010-08-02 06:39:44 +03:00
irq_comm.c KVM: Convert mask notifiers to use irqchip/pin instead of gsi 2010-08-02 06:40:39 +03:00
kvm_main.c KVM: x86: Add clock sync request to hardware enable 2010-10-24 10:51:24 +02:00