[PATCH 0/3] KVM: Make kvm_lock non-raw

From: Paolo Bonzini
Date: Mon Sep 16 2013 - 10:06:27 EST


Paul Gortmaker reported a BUG on preempt-rt kernels, due to taking the
mmu_lock within the raw kvm_lock in mmu_shrink_scan. He provided a
patch that shrunk the kvm_lock critical section so that the mmu_lock
critical section does not nest with it, but in the end there is no reason
for the vm_list to be protected by a raw spinlock. Only manipulations
of kvm_usage_count and the consequent hardware_enable/disable operations
are not preemptable.

This small series thus splits the kvm_lock in the "raw" part and the
"non-raw" part.

Paul, could you please provide your Tested-by?

Thanks,

Paolo

Paolo Bonzini (3):
KVM: cleanup (physical) CPU hotplug
KVM: protect kvm_usage_count with its own spinlock
KVM: Convert kvm_lock back to non-raw spinlock

Documentation/virtual/kvm/locking.txt | 8 ++++--
arch/x86/kvm/mmu.c | 4 +--
arch/x86/kvm/x86.c | 8 +++---
include/linux/kvm_host.h | 2 +-
virt/kvm/kvm_main.c | 51 ++++++++++++++++++-----------------
5 files changed, 40 insertions(+), 33 deletions(-)

--
1.8.3.1

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