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https://github.com/clearlinux/kvmtool.git
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Sasha Levin
5124781543
Adds a debug mode which allows to switch the brlock into a big rwlock. This can be used to verify we don't end up with a BKL kind of lock with the current brlock implementation. Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
42 lines
1004 B
C
42 lines
1004 B
C
#ifndef KVM__BRLOCK_H
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#define KVM__BRLOCK_H
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#include "kvm/kvm.h"
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#include "kvm/barrier.h"
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/*
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* brlock is a lock which is very cheap for reads, but very expensive
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* for writes.
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* This lock will be used when updates are very rare and reads are common.
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* This lock is currently implemented by stopping the guest while
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* performing the updates. We assume that the only threads whichread from
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* the locked data are VCPU threads, and the only writer isn't a VCPU thread.
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*/
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#ifndef barrier
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#define barrier() __asm__ __volatile__("": : :"memory")
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#endif
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#ifdef KVM_BRLOCK_DEBUG
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#include "kvm/rwsem.h"
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DECLARE_RWSEM(brlock_sem);
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#define br_read_lock() down_read(&brlock_sem);
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#define br_read_unlock() up_read(&brlock_sem);
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#define br_write_lock() down_write(&brlock_sem);
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#define br_write_unlock() up_write(&brlock_sem);
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#else
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#define br_read_lock() barrier()
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#define br_read_unlock() barrier()
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#define br_write_lock() kvm__pause()
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#define br_write_unlock() kvm__continue()
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#endif
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#endif
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