diff options
| -rw-r--r-- | drivers/vfio/group.c | 44 | ||||
| -rw-r--r-- | drivers/vfio/vfio.h | 15 | ||||
| -rw-r--r-- | drivers/vfio/vfio_main.c | 63 | ||||
| -rw-r--r-- | include/linux/vfio.h | 2 |
4 files changed, 109 insertions, 15 deletions
diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c index bb24b2f0271e..98621ac082f0 100644 --- a/drivers/vfio/group.c +++ b/drivers/vfio/group.c @@ -154,6 +154,18 @@ out_unlock: return ret; } +static void vfio_device_group_get_kvm_safe(struct vfio_device *device) +{ + spin_lock(&device->group->kvm_ref_lock); + if (!device->group->kvm) + goto unlock; + + _vfio_device_get_kvm_safe(device, device->group->kvm); + +unlock: + spin_unlock(&device->group->kvm_ref_lock); +} + static int vfio_device_group_open(struct vfio_device *device) { int ret; @@ -164,13 +176,23 @@ static int vfio_device_group_open(struct vfio_device *device) goto out_unlock; } + mutex_lock(&device->dev_set->lock); + /* - * Here we pass the KVM pointer with the group under the lock. If the - * device driver will use it, it must obtain a reference and release it - * during close_device. + * Before the first device open, get the KVM pointer currently + * associated with the group (if there is one) and obtain a reference + * now that will be held until the open_count reaches 0 again. Save + * the pointer in the device for use by drivers. */ - ret = vfio_device_open(device, device->group->iommufd, - device->group->kvm); + if (device->open_count == 0) + vfio_device_group_get_kvm_safe(device); + + ret = vfio_device_open(device, device->group->iommufd, device->kvm); + + if (device->open_count == 0) + vfio_device_put_kvm(device); + + mutex_unlock(&device->dev_set->lock); out_unlock: mutex_unlock(&device->group->group_lock); @@ -180,7 +202,14 @@ out_unlock: void vfio_device_group_close(struct vfio_device *device) { mutex_lock(&device->group->group_lock); + mutex_lock(&device->dev_set->lock); + vfio_device_close(device, device->group->iommufd); + + if (device->open_count == 0) + vfio_device_put_kvm(device); + + mutex_unlock(&device->dev_set->lock); mutex_unlock(&device->group->group_lock); } @@ -450,6 +479,7 @@ static struct vfio_group *vfio_group_alloc(struct iommu_group *iommu_group, refcount_set(&group->drivers, 1); mutex_init(&group->group_lock); + spin_lock_init(&group->kvm_ref_lock); INIT_LIST_HEAD(&group->device_list); mutex_init(&group->device_lock); group->iommu_group = iommu_group; @@ -803,9 +833,9 @@ void vfio_file_set_kvm(struct file *file, struct kvm *kvm) if (!vfio_file_is_group(file)) return; - mutex_lock(&group->group_lock); + spin_lock(&group->kvm_ref_lock); group->kvm = kvm; - mutex_unlock(&group->group_lock); + spin_unlock(&group->kvm_ref_lock); } EXPORT_SYMBOL_GPL(vfio_file_set_kvm); diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h index d5fa896b5a85..8ec3a5db23f5 100644 --- a/drivers/vfio/vfio.h +++ b/drivers/vfio/vfio.h @@ -74,6 +74,7 @@ struct vfio_group { struct file *opened_file; struct blocking_notifier_head notifier; struct iommufd_ctx *iommufd; + spinlock_t kvm_ref_lock; }; int vfio_device_set_group(struct vfio_device *device, @@ -244,4 +245,18 @@ extern bool vfio_noiommu __read_mostly; enum { vfio_noiommu = false }; #endif +#ifdef CONFIG_HAVE_KVM +void _vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm); +void vfio_device_put_kvm(struct vfio_device *device); +#else +static inline void _vfio_device_get_kvm_safe(struct vfio_device *device, + struct kvm *kvm) +{ +} + +static inline void vfio_device_put_kvm(struct vfio_device *device) +{ +} +#endif + #endif diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c index 5177bb061b17..28c47cd6a6b5 100644 --- a/drivers/vfio/vfio_main.c +++ b/drivers/vfio/vfio_main.c @@ -16,6 +16,9 @@ #include <linux/fs.h> #include <linux/idr.h> #include <linux/iommu.h> +#ifdef CONFIG_HAVE_KVM +#include <linux/kvm_host.h> +#endif #include <linux/list.h> #include <linux/miscdevice.h> #include <linux/module.h> @@ -338,6 +341,55 @@ void vfio_unregister_group_dev(struct vfio_device *device) } EXPORT_SYMBOL_GPL(vfio_unregister_group_dev); +#ifdef CONFIG_HAVE_KVM +void _vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm) +{ + void (*pfn)(struct kvm *kvm); + bool (*fn)(struct kvm *kvm); + bool ret; + + lockdep_assert_held(&device->dev_set->lock); + + pfn = symbol_get(kvm_put_kvm); + if (WARN_ON(!pfn)) + return; + + fn = symbol_get(kvm_get_kvm_safe); + if (WARN_ON(!fn)) { + symbol_put(kvm_put_kvm); + return; + } + + ret = fn(kvm); + symbol_put(kvm_get_kvm_safe); + if (!ret) { + symbol_put(kvm_put_kvm); + return; + } + + device->put_kvm = pfn; + device->kvm = kvm; +} + +void vfio_device_put_kvm(struct vfio_device *device) +{ + lockdep_assert_held(&device->dev_set->lock); + + if (!device->kvm) + return; + + if (WARN_ON(!device->put_kvm)) + goto clear; + + device->put_kvm(device->kvm); + device->put_kvm = NULL; + symbol_put(kvm_put_kvm); + +clear: + device->kvm = NULL; +} +#endif + /* true if the vfio_device has open_device() called but not close_device() */ static bool vfio_assert_device_open(struct vfio_device *device) { @@ -361,7 +413,6 @@ static int vfio_device_first_open(struct vfio_device *device, if (ret) goto err_module_put; - device->kvm = kvm; if (device->ops->open_device) { ret = device->ops->open_device(device); if (ret) @@ -370,7 +421,6 @@ static int vfio_device_first_open(struct vfio_device *device, return 0; err_unuse_iommu: - device->kvm = NULL; if (iommufd) vfio_iommufd_unbind(device); else @@ -387,7 +437,6 @@ static void vfio_device_last_close(struct vfio_device *device, if (device->ops->close_device) device->ops->close_device(device); - device->kvm = NULL; if (iommufd) vfio_iommufd_unbind(device); else @@ -400,14 +449,14 @@ int vfio_device_open(struct vfio_device *device, { int ret = 0; - mutex_lock(&device->dev_set->lock); + lockdep_assert_held(&device->dev_set->lock); + device->open_count++; if (device->open_count == 1) { ret = vfio_device_first_open(device, iommufd, kvm); if (ret) device->open_count--; } - mutex_unlock(&device->dev_set->lock); return ret; } @@ -415,12 +464,12 @@ int vfio_device_open(struct vfio_device *device, void vfio_device_close(struct vfio_device *device, struct iommufd_ctx *iommufd) { - mutex_lock(&device->dev_set->lock); + lockdep_assert_held(&device->dev_set->lock); + vfio_assert_device_open(device); if (device->open_count == 1) vfio_device_last_close(device, iommufd); device->open_count--; - mutex_unlock(&device->dev_set->lock); } /* diff --git a/include/linux/vfio.h b/include/linux/vfio.h index 35be78e9ae57..87ff862ff555 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -46,7 +46,6 @@ struct vfio_device { struct vfio_device_set *dev_set; struct list_head dev_set_list; unsigned int migration_flags; - /* Driver must reference the kvm during open_device or never touch it */ struct kvm *kvm; /* Members below here are private, not for driver use */ @@ -58,6 +57,7 @@ struct vfio_device { struct list_head group_next; struct list_head iommu_entry; struct iommufd_access *iommufd_access; + void (*put_kvm)(struct kvm *kvm); #if IS_ENABLED(CONFIG_IOMMUFD) struct iommufd_device *iommufd_device; struct iommufd_ctx *iommufd_ictx; |