KVM: arm64: Expose {un,}lock_all_vcpus() to the rest of KVM

Being able to lock/unlock all vcpus in one go is a feature that
only the vgic has enjoyed so far. Let's be brave and expose it
to the world.

Reviewed-by: Colton Lewis <coltonlewis@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230330174800.2677007-7-maz@kernel.org

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index bcd774d..002a10c 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -922,6 +922,9 @@ void kvm_reset_sys_regs(struct kvm_vcpu *vcpu);
 
 int __init kvm_sys_reg_table_init(void);
 
+bool lock_all_vcpus(struct kvm *kvm);
+void unlock_all_vcpus(struct kvm *kvm);
+
 /* MMIO helpers */
 void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data);
 unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len);

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 3bd732e..ae5110c 100644 (file)
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1484,6 +1484,49 @@ long kvm_arch_vm_ioctl(struct file *filp,
        }
 }
 
+/* unlocks vcpus from @vcpu_lock_idx and smaller */
+static void unlock_vcpus(struct kvm *kvm, int vcpu_lock_idx)
+{
+       struct kvm_vcpu *tmp_vcpu;
+
+       for (; vcpu_lock_idx >= 0; vcpu_lock_idx--) {
+               tmp_vcpu = kvm_get_vcpu(kvm, vcpu_lock_idx);
+               mutex_unlock(&tmp_vcpu->mutex);
+       }
+}
+
+void unlock_all_vcpus(struct kvm *kvm)
+{
+       lockdep_assert_held(&kvm->lock);
+
+       unlock_vcpus(kvm, atomic_read(&kvm->online_vcpus) - 1);
+}
+
+/* Returns true if all vcpus were locked, false otherwise */
+bool lock_all_vcpus(struct kvm *kvm)
+{
+       struct kvm_vcpu *tmp_vcpu;
+       unsigned long c;
+
+       lockdep_assert_held(&kvm->lock);
+
+       /*
+        * Any time a vcpu is in an ioctl (including running), the
+        * core KVM code tries to grab the vcpu->mutex.
+        *
+        * By grabbing the vcpu->mutex of all VCPUs we ensure that no
+        * other VCPUs can fiddle with the state while we access it.
+        */
+       kvm_for_each_vcpu(c, tmp_vcpu, kvm) {
+               if (!mutex_trylock(&tmp_vcpu->mutex)) {
+                       unlock_vcpus(kvm, c - 1);
+                       return false;
+               }
+       }
+
+       return true;
+}
+
 static unsigned long nvhe_percpu_size(void)
 {
        return (unsigned long)CHOOSE_NVHE_SYM(__per_cpu_end) -

diff --git a/arch/arm64/kvm/vgic/vgic-kvm-device.c b/arch/arm64/kvm/vgic/vgic-kvm-device.c
index edeac23..04dd688 100644 (file)
--- a/arch/arm64/kvm/vgic/vgic-kvm-device.c
+++ b/arch/arm64/kvm/vgic/vgic-kvm-device.c
@@ -342,44 +342,6 @@ int vgic_v2_parse_attr(struct kvm_device *dev, struct kvm_device_attr *attr,
        return 0;
 }
 
-/* unlocks vcpus from @vcpu_lock_idx and smaller */
-static void unlock_vcpus(struct kvm *kvm, int vcpu_lock_idx)
-{
-       struct kvm_vcpu *tmp_vcpu;
-
-       for (; vcpu_lock_idx >= 0; vcpu_lock_idx--) {
-               tmp_vcpu = kvm_get_vcpu(kvm, vcpu_lock_idx);
-               mutex_unlock(&tmp_vcpu->mutex);
-       }
-}
-
-void unlock_all_vcpus(struct kvm *kvm)
-{
-       unlock_vcpus(kvm, atomic_read(&kvm->online_vcpus) - 1);
-}
-
-/* Returns true if all vcpus were locked, false otherwise */
-bool lock_all_vcpus(struct kvm *kvm)
-{
-       struct kvm_vcpu *tmp_vcpu;
-       unsigned long c;
-
-       /*
-        * Any time a vcpu is run, vcpu_load is called which tries to grab the
-        * vcpu->mutex.  By grabbing the vcpu->mutex of all VCPUs we ensure
-        * that no other VCPUs are run and fiddle with the vgic state while we
-        * access it.
-        */
-       kvm_for_each_vcpu(c, tmp_vcpu, kvm) {
-               if (!mutex_trylock(&tmp_vcpu->mutex)) {
-                       unlock_vcpus(kvm, c - 1);
-                       return false;
-               }
-       }
-
-       return true;
-}
-
 /**
  * vgic_v2_attr_regs_access - allows user space to access VGIC v2 state
  *

diff --git a/arch/arm64/kvm/vgic/vgic.h b/arch/arm64/kvm/vgic/vgic.h
index 7f7f3c5..f9923be 100644 (file)
--- a/arch/arm64/kvm/vgic/vgic.h
+++ b/arch/arm64/kvm/vgic/vgic.h
@@ -273,9 +273,6 @@ int vgic_init(struct kvm *kvm);
 void vgic_debug_init(struct kvm *kvm);
 void vgic_debug_destroy(struct kvm *kvm);
 
-bool lock_all_vcpus(struct kvm *kvm);
-void unlock_all_vcpus(struct kvm *kvm);
-
 static inline int vgic_v3_max_apr_idx(struct kvm_vcpu *vcpu)
 {
        struct vgic_cpu *cpu_if = &vcpu->arch.vgic_cpu;