mirror of
https://github.com/clearlinux/kvmtool.git
synced 2026-09-04 04:31:27 +00:00
Sasha Levin
4346fd8f1e
This was ugly, and now we get rid of it. Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
42 lines
1.0 KiB
C
42 lines
1.0 KiB
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(kvm) down_read(&brlock_sem);
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#define br_read_unlock(kvm) up_read(&brlock_sem);
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#define br_write_lock(kvm) down_write(&brlock_sem);
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#define br_write_unlock(kvm) up_write(&brlock_sem);
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#else
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#define br_read_lock(kvm) barrier()
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#define br_read_unlock(kvm) barrier()
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#define br_write_lock(kvm) kvm__pause(kvm)
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#define br_write_unlock(kvm) kvm__continue(kvm)
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#endif
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#endif
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