kvm: Convert kvm_lock to a mutex

commit 0d9ce162cf46c99628cc5da9510b959c7976735b upstream.

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: Junaid Shahid <junaids@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[bwh: Backported to 4.9:
 - Drop changes in kvm_hyperv_tsc_notifier(), vm_stat_clear(),
   vcpu_stat_clear(), kvm_uevent_notify_change()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/virtual/kvm/locking.txt b/Documentation/virtual/kvm/locking.txt
index e5dd9f4d61008ad6431e067b900608788e573020..46ef3680c8abc62d2afd6eeb50b7dc71b309bb33 100644 (file)
--- a/Documentation/virtual/kvm/locking.txt
+++ b/Documentation/virtual/kvm/locking.txt
@@ -13,8 +13,8 @@ The acquisition orders for mutexes are as follows:
 - kvm->slots_lock is taken outside kvm->irq_lock, though acquiring
   them together is quite rare.
 
-For spinlocks, kvm_lock is taken outside kvm->mmu_lock.  Everything
-else is a leaf: no other lock is taken inside the critical sections.
+Everything else is a leaf: no other lock is taken inside the critical
+sections.
 
 2: Exception
 ------------
@@ -142,7 +142,7 @@ See the comments in spte_has_volatile_bits() and mmu_spte_update().
 ------------
 
 Name:          kvm_lock
-Type:          spinlock_t
+Type:          mutex
 Arch:          any
 Protects:      - vm_list
 

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 3dc96b455e0c762f87605a9689c3a85ea17bea24..37c254677ccdaa56e18d329788b6c8464ac676f4 100644 (file)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1422,13 +1422,13 @@ 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);
 

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index df142bb700f6249f817dbb7f38a638c35a1d49f6..57aa700a1cac12a5700e94e01babaad7b7456614 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -4979,7 +4979,7 @@ 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;
@@ -5029,7 +5029,7 @@ unlock:
                break;
        }
 
-       spin_unlock(&kvm_lock);
+       mutex_unlock(&kvm_lock);
        return freed;
 }
 

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7bbc027e0aab3baf74809c68e104fa9e2ec14fed..a416e25c831d37c3adcd470a7b9079033ba28171 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5978,17 +5978,17 @@ static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long va
 
        smp_call_function_single(freq->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 != freq->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) {
                /*
@@ -6126,12 +6126,12 @@ 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);

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index eb55374b73f30302c9dcd868fb70372ab94ecf2b..7ecb32b43dc7355786d4a1b18809340f4240da5b 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -129,7 +129,7 @@ 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 {

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c72586a094edb5ee23d44e3bfa2ca0a88d197c18..7af67b2787539a1f37d6bdd4c5ec791bcc6391d2 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -87,7 +87,7 @@ module_param(halt_poll_ns_shrink, uint, S_IRUGO | S_IWUSR);
  *     kvm->lock --> kvm->slots_lock --> kvm->irq_lock
  */
 
-DEFINE_SPINLOCK(kvm_lock);
+DEFINE_MUTEX(kvm_lock);
 static DEFINE_RAW_SPINLOCK(kvm_count_lock);
 LIST_HEAD(vm_list);
 
@@ -666,9 +666,9 @@ static struct kvm *kvm_create_vm(unsigned long type)
        if (r)
                goto out_err;
 
-       spin_lock(&kvm_lock);
+       mutex_lock(&kvm_lock);
        list_add(&kvm->vm_list, &vm_list);
-       spin_unlock(&kvm_lock);
+       mutex_unlock(&kvm_lock);
 
        preempt_notifier_inc();
 
@@ -724,9 +724,9 @@ static void kvm_destroy_vm(struct kvm *kvm)
 
        kvm_destroy_vm_debugfs(kvm);
        kvm_arch_sync_events(kvm);
-       spin_lock(&kvm_lock);
+       mutex_lock(&kvm_lock);
        list_del(&kvm->vm_list);
-       spin_unlock(&kvm_lock);
+       mutex_unlock(&kvm_lock);
        kvm_free_irq_routing(kvm);
        for (i = 0; i < KVM_NR_BUSES; i++) {
                if (kvm->buses[i])
@@ -3752,13 +3752,13 @@ static int vm_stat_get(void *_offset, u64 *val)
        u64 tmp_val;
 
        *val = 0;
-       spin_lock(&kvm_lock);
+       mutex_lock(&kvm_lock);
        list_for_each_entry(kvm, &vm_list, vm_list) {
                stat_tmp.kvm = kvm;
                vm_stat_get_per_vm((void *)&stat_tmp, &tmp_val);
                *val += tmp_val;
        }
-       spin_unlock(&kvm_lock);
+       mutex_unlock(&kvm_lock);
        return 0;
 }
 
@@ -3772,13 +3772,13 @@ static int vcpu_stat_get(void *_offset, u64 *val)
        u64 tmp_val;
 
        *val = 0;
-       spin_lock(&kvm_lock);
+       mutex_lock(&kvm_lock);
        list_for_each_entry(kvm, &vm_list, vm_list) {
                stat_tmp.kvm = kvm;
                vcpu_stat_get_per_vm((void *)&stat_tmp, &tmp_val);
                *val += tmp_val;
        }
-       spin_unlock(&kvm_lock);
+       mutex_unlock(&kvm_lock);
        return 0;
 }