Commit 0d9ce162 authored by Junaid Shahid's avatar Junaid Shahid Committed by Paolo Bonzini
Browse files

kvm: Convert kvm_lock to a mutex 



It doesn't seem as if there is any particular need for kvm_lock to be a
spinlock, so convert the lock to a mutex so that sleepable functions (in
particular cond_resched()) can be called while holding it.

Signed-off-by: default avatarJunaid Shahid <junaids@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 1ae4de23

Documentation/virtual/kvm/locking.txt

+1 −3
Original line number Diff line number Diff line
@@ -15,8 +15,6 @@ The acquisition orders for mutexes are as follows: 


On x86, vcpu->mutex is taken outside kvm->arch.hyperv.hv_lock.



For spinlocks, kvm_lock is taken outside kvm->mmu_lock.



Everything else is a leaf: no other lock is taken inside the critical

sections.
@@ -169,7 +167,7 @@ which time it will be set using the Dirty tracking mechanism described above. 
------------



Name:		kvm_lock

Type:		spinlock_t

Type:		mutex

Arch:		any

Protects:	- vm_list

arch/s390/kvm/kvm-s390.c

+2 −2
Original line number Diff line number Diff line
@@ -2423,13 +2423,13 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) 
	kvm->arch.sca = (struct bsca_block *) get_zeroed_page(alloc_flags);

	if (!kvm->arch.sca)

		goto out_err;

	spin_lock(&kvm_lock);

	mutex_lock(&kvm_lock);

	sca_offset += 16;

	if (sca_offset + sizeof(struct bsca_block) > PAGE_SIZE)

		sca_offset = 0;

	kvm->arch.sca = (struct bsca_block *)

			((char *) kvm->arch.sca + sca_offset);

	spin_unlock(&kvm_lock);

	mutex_unlock(&kvm_lock);



	sprintf(debug_name, "kvm-%u", current->pid);

arch/x86/kvm/mmu.c

+2 −2
Original line number Diff line number Diff line
@@ -5956,7 +5956,7 @@ mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) 
	int nr_to_scan = sc->nr_to_scan;

	unsigned long freed = 0;



	spin_lock(&kvm_lock);

	mutex_lock(&kvm_lock);



	list_for_each_entry(kvm, &vm_list, vm_list) {

		int idx;
@@ -5998,7 +5998,7 @@ mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) 
		break;

	}



	spin_unlock(&kvm_lock);

	mutex_unlock(&kvm_lock);

	return freed;

}

arch/x86/kvm/x86.c

+7 −7
Original line number Diff line number Diff line
@@ -6719,7 +6719,7 @@ static void kvm_hyperv_tsc_notifier(void) 
	struct kvm_vcpu *vcpu;

	int cpu;



	spin_lock(&kvm_lock);

	mutex_lock(&kvm_lock);

	list_for_each_entry(kvm, &vm_list, vm_list)

		kvm_make_mclock_inprogress_request(kvm);
@@ -6745,7 +6745,7 @@ static void kvm_hyperv_tsc_notifier(void) 


		spin_unlock(&ka->pvclock_gtod_sync_lock);

	}

	spin_unlock(&kvm_lock);

	mutex_unlock(&kvm_lock);

}

#endif
@@ -6796,17 +6796,17 @@ static void __kvmclock_cpufreq_notifier(struct cpufreq_freqs *freq, int cpu) 


	smp_call_function_single(cpu, tsc_khz_changed, freq, 1);



	spin_lock(&kvm_lock);

	mutex_lock(&kvm_lock);

	list_for_each_entry(kvm, &vm_list, vm_list) {

		kvm_for_each_vcpu(i, vcpu, kvm) {

			if (vcpu->cpu != cpu)

				continue;

			kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);

			if (vcpu->cpu != smp_processor_id())

			if (vcpu->cpu != raw_smp_processor_id())

				send_ipi = 1;

		}

	}

	spin_unlock(&kvm_lock);

	mutex_unlock(&kvm_lock);



	if (freq->old < freq->new && send_ipi) {

		/*
@@ -6929,12 +6929,12 @@ static void pvclock_gtod_update_fn(struct work_struct *work) 
	struct kvm_vcpu *vcpu;

	int i;



	spin_lock(&kvm_lock);

	mutex_lock(&kvm_lock);

	list_for_each_entry(kvm, &vm_list, vm_list)

		kvm_for_each_vcpu(i, vcpu, kvm)

			kvm_make_request(KVM_REQ_MASTERCLOCK_UPDATE, vcpu);

	atomic_set(&kvm_guest_has_master_clock, 0);

	spin_unlock(&kvm_lock);

	mutex_unlock(&kvm_lock);

}



static DECLARE_WORK(pvclock_gtod_work, pvclock_gtod_update_fn);

include/linux/kvm_host.h

+1 −1
Original line number Diff line number Diff line
@@ -162,7 +162,7 @@ static inline bool is_error_page(struct page *page) 


extern struct kmem_cache *kvm_vcpu_cache;



extern spinlock_t kvm_lock;

extern struct mutex kvm_lock;

extern struct list_head vm_list;



struct kvm_io_range {