Hi Alex, > From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx] > Sent: Thursday, January 30, 2020 7:57 AM > To: Liu, Yi L <yi.l.liu@xxxxxxxxx> > Subject: Re: [RFC v3 3/8] vfio: Reclaim PASIDs when application is down > > On Wed, 29 Jan 2020 04:11:47 -0800 > "Liu, Yi L" <yi.l.liu@xxxxxxxxx> wrote: > > > From: Liu Yi L <yi.l.liu@xxxxxxxxx> > > > > When userspace application is down, kernel should reclaim the PASIDs > > allocated for this application to avoid PASID leak. This patch adds a > > PASID list in vfio_mm structure to track the allocated PASIDs. The > > PASID reclaim will be triggered when last vfio container is released. > > > > Previous discussions: > > https://patchwork.kernel.org/patch/11209429/ > > > > Cc: Kevin Tian <kevin.tian@xxxxxxxxx> > > CC: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx> > > Cc: Alex Williamson <alex.williamson@xxxxxxxxxx> > > Cc: Eric Auger <eric.auger@xxxxxxxxxx> > > Cc: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx> > > Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx> > > --- > > drivers/vfio/vfio.c | 61 > > +++++++++++++++++++++++++++++++++++++++++++++++++--- > > include/linux/vfio.h | 6 ++++++ > > 2 files changed, 64 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index > > c43c757..425d60a 100644 > > --- a/drivers/vfio/vfio.c > > +++ b/drivers/vfio/vfio.c > > @@ -2148,15 +2148,31 @@ static struct vfio_mm *vfio_create_mm(struct > mm_struct *mm) > > vmm->pasid_quota = VFIO_DEFAULT_PASID_QUOTA; > > vmm->pasid_count = 0; > > mutex_init(&vmm->pasid_lock); > > + INIT_LIST_HEAD(&vmm->pasid_list); > > > > list_add(&vmm->vfio_next, &vfio.vfio_mm_list); > > > > return vmm; > > } > > > > +static void vfio_mm_reclaim_pasid(struct vfio_mm *vmm) { > > + struct pasid_node *pnode, *tmp; > > + > > + mutex_lock(&vmm->pasid_lock); > > + list_for_each_entry_safe(pnode, tmp, &vmm->pasid_list, next) { > > + pr_info("%s, reclaim pasid: %u\n", __func__, pnode->pasid); > > + list_del(&pnode->next); > > + ioasid_free(pnode->pasid); > > + kfree(pnode); > > + } > > + mutex_unlock(&vmm->pasid_lock); > > +} > > + > > static void vfio_mm_unlock_and_free(struct vfio_mm *vmm) { > > mutex_unlock(&vfio.vfio_mm_lock); > > + vfio_mm_reclaim_pasid(vmm); > > kfree(vmm); > > } > > > > @@ -2204,6 +2220,39 @@ struct vfio_mm *vfio_mm_get_from_task(struct > > task_struct *task) } EXPORT_SYMBOL_GPL(vfio_mm_get_from_task); > > > > +/** > > + * Caller should hold vmm->pasid_lock */ static int > > +vfio_mm_insert_pasid_node(struct vfio_mm *vmm, u32 pasid) { > > + struct pasid_node *pnode; > > + > > + pnode = kzalloc(sizeof(*pnode), GFP_KERNEL); > > + if (!pnode) > > + return -ENOMEM; > > + pnode->pasid = pasid; > > + list_add(&pnode->next, &vmm->pasid_list); > > + > > + return 0; > > +} > > + > > +/** > > + * Caller should hold vmm->pasid_lock */ static void > > +vfio_mm_remove_pasid_node(struct vfio_mm *vmm, u32 pasid) { > > + struct pasid_node *pnode, *tmp; > > + > > + list_for_each_entry_safe(pnode, tmp, &vmm->pasid_list, next) { > > + if (pnode->pasid == pasid) { > > + list_del(&pnode->next); > > + kfree(pnode); > > + break; > > + } > > The _safe() list walk variant is only needed when we continue to walk the list after > removing an entry. Thanks, Nice catch. thanks, :-) Regards, Yi Liu
