Hi Eric, > From: Auger Eric <eric.auger@xxxxxxxxxx> > Sent: Thursday, August 13, 2020 11:07 PM > > Yi, > > On 7/28/20 8:27 AM, Liu Yi L wrote: > > Shared Virtual Addressing (a.k.a Shared Virtual Memory) allows sharing > > multiple process virtual address spaces with the device for simplified > > programming model. PASID is used to tag an virtual address space in > > DMA requests and to identify the related translation structure in > > IOMMU. When a PASID-capable device is assigned to a VM, we want the > > same capability of using PASID to tag guest process virtual address > > spaces to achieve virtual SVA (vSVA). > > > > PASID management for guest is vendor specific. Some vendors (e.g. > > Intel > > VT-d) requires system-wide managed PASIDs across all devices, > > regardless of whether a device is used by host or assigned to guest. > > Other vendors (e.g. ARM SMMU) may allow PASIDs managed per-device thus > > could be fully delegated to the guest for assigned devices. > > > > For system-wide managed PASIDs, this patch introduces a vfio module to > > handle explicit PASID alloc/free requests from guest. Allocated PASIDs > > are associated to a process (or, mm_struct) in IOASID core. A vfio_mm > > object is introduced to track mm_struct. Multiple VFIO containers > > within a process share the same vfio_mm object. > > > > A quota mechanism is provided to prevent malicious user from > > exhausting available PASIDs. Currently the quota is a global parameter > > applied to all VFIO devices. In the future per-device quota might be supported too. > > > > Cc: Kevin Tian <kevin.tian@xxxxxxxxx> > > CC: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx> > > Cc: Eric Auger <eric.auger@xxxxxxxxxx> > > Cc: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx> > > Cc: Joerg Roedel <joro@xxxxxxxxxx> > > Cc: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> > > Suggested-by: Alex Williamson <alex.williamson@xxxxxxxxxx> > > Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx> > > --- > > v5 -> v6: > > *) address comments from Eric. Add vfio_unlink_pasid() to be consistent > > with vfio_unlink_dma(). Add a comment in vfio_pasid_exit(). > > > > v4 -> v5: > > *) address comments from Eric Auger. > > *) address the comments from Alex on the pasid free range support. Added > > per vfio_mm pasid r-b tree. > > https://lore.kernel.org/kvm/20200709082751.320742ab@xxxxxxx/ > > > > v3 -> v4: > > *) fix lock leam in vfio_mm_get_from_task() > > *) drop pasid_quota field in struct vfio_mm > > *) vfio_mm_get_from_task() returns ERR_PTR(-ENOTTY) when > > !CONFIG_VFIO_PASID > > > > v1 -> v2: > > *) added in v2, split from the pasid alloc/free support of v1 > > --- > > drivers/vfio/Kconfig | 5 + > > drivers/vfio/Makefile | 1 + > > drivers/vfio/vfio_pasid.c | 248 > ++++++++++++++++++++++++++++++++++++++++++++++ > > include/linux/vfio.h | 28 ++++++ > > 4 files changed, 282 insertions(+) > > create mode 100644 drivers/vfio/vfio_pasid.c > > > > diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig index > > fd17db9..3d8a108 100644 > > --- a/drivers/vfio/Kconfig > > +++ b/drivers/vfio/Kconfig > > @@ -19,6 +19,11 @@ config VFIO_VIRQFD > > depends on VFIO && EVENTFD > > default n > > > > +config VFIO_PASID > > + tristate > > + depends on IOASID && VFIO > > + default n > > + > > menuconfig VFIO > > tristate "VFIO Non-Privileged userspace driver framework" > > depends on IOMMU_API > > diff --git a/drivers/vfio/Makefile b/drivers/vfio/Makefile index > > de67c47..bb836a3 100644 > > --- a/drivers/vfio/Makefile > > +++ b/drivers/vfio/Makefile > > @@ -3,6 +3,7 @@ vfio_virqfd-y := virqfd.o > > > > obj-$(CONFIG_VFIO) += vfio.o > > obj-$(CONFIG_VFIO_VIRQFD) += vfio_virqfd.o > > +obj-$(CONFIG_VFIO_PASID) += vfio_pasid.o > > obj-$(CONFIG_VFIO_IOMMU_TYPE1) += vfio_iommu_type1.o > > obj-$(CONFIG_VFIO_IOMMU_SPAPR_TCE) += vfio_iommu_spapr_tce.o > > obj-$(CONFIG_VFIO_SPAPR_EEH) += vfio_spapr_eeh.o diff --git > > a/drivers/vfio/vfio_pasid.c b/drivers/vfio/vfio_pasid.c new file mode > > 100644 index 0000000..befcf29 > > --- /dev/null > > +++ b/drivers/vfio/vfio_pasid.c > > @@ -0,0 +1,248 @@ > > +// SPDX-License-Identifier: GPL-2.0-only > > +/* > > + * Copyright (C) 2020 Intel Corporation. > > + * Author: Liu Yi L <yi.l.liu@xxxxxxxxx> > > + * > > + */ > > + > > +#include <linux/vfio.h> > > +#include <linux/eventfd.h> > not needed oh, yes. > > +#include <linux/file.h> > > +#include <linux/module.h> > > +#include <linux/slab.h> > > +#include <linux/sched/mm.h> > > + > > +#define DRIVER_VERSION "0.1" > > +#define DRIVER_AUTHOR "Liu Yi L <yi.l.liu@xxxxxxxxx>" > > +#define DRIVER_DESC "PASID management for VFIO bus drivers" > > + > > +#define VFIO_DEFAULT_PASID_QUOTA 1000 > > +static int pasid_quota = VFIO_DEFAULT_PASID_QUOTA; > > +module_param_named(pasid_quota, pasid_quota, uint, 0444); > > +MODULE_PARM_DESC(pasid_quota, > > + "Set the quota for max number of PASIDs that an application is > > +allowed to request (default 1000)"); > > + > > +struct vfio_mm_token { > > + unsigned long long val; > > +}; > > + > > +struct vfio_mm { > > + struct kref kref; > > + int ioasid_sid; > > + struct mutex pasid_lock; > > + struct rb_root pasid_list; > > + struct list_head next; > > + struct vfio_mm_token token; > > +}; > > + > > +static struct mutex vfio_mm_lock; > > +static struct list_head vfio_mm_list; > > + > > +struct vfio_pasid { > > + struct rb_node node; > > + ioasid_t pasid; > > +}; > > + > > +static void vfio_remove_all_pasids(struct vfio_mm *vmm); > > + > > +/* called with vfio.vfio_mm_lock held */ static void > > +vfio_mm_release(struct kref *kref) { > > + struct vfio_mm *vmm = container_of(kref, struct vfio_mm, kref); > > + > > + list_del(&vmm->next); > > + mutex_unlock(&vfio_mm_lock); > > + vfio_remove_all_pasids(vmm); > > + ioasid_free_set(vmm->ioasid_sid, true); > > + kfree(vmm); > > +} > > + > > +void vfio_mm_put(struct vfio_mm *vmm) { > > + kref_put_mutex(&vmm->kref, vfio_mm_release, &vfio_mm_lock); } > > + > > +static void vfio_mm_get(struct vfio_mm *vmm) { > > + kref_get(&vmm->kref); > > +} > > + > > +struct vfio_mm *vfio_mm_get_from_task(struct task_struct *task) { > > + struct mm_struct *mm = get_task_mm(task); > > + struct vfio_mm *vmm; > > + unsigned long long val = (unsigned long long)mm; > > + int ret; > > + > > + mutex_lock(&vfio_mm_lock); > > + /* Search existing vfio_mm with current mm pointer */ > > + list_for_each_entry(vmm, &vfio_mm_list, next) { > > + if (vmm->token.val == val) { > > + vfio_mm_get(vmm); > > + goto out; > > + } > > + } > > + > > + vmm = kzalloc(sizeof(*vmm), GFP_KERNEL); > > + if (!vmm) { > > + vmm = ERR_PTR(-ENOMEM); > > + goto out; > > + } > > + > > + /* > > + * IOASID core provides a 'IOASID set' concept to track all > > + * PASIDs associated with a token. Here we use mm_struct as > > + * the token and create a IOASID set per mm_struct. All the > > + * containers of the process share the same IOASID set. > > + */ > > + ret = ioasid_alloc_set((struct ioasid_set *)mm, pasid_quota, > > + &vmm->ioasid_sid); > > + if (ret) { > > + kfree(vmm); > > + vmm = ERR_PTR(ret); > > + goto out; > > + } > > + > > + kref_init(&vmm->kref); > > + vmm->token.val = val; > > + mutex_init(&vmm->pasid_lock); > > + vmm->pasid_list = RB_ROOT; > > + > > + list_add(&vmm->next, &vfio_mm_list);> +out: > > + mutex_unlock(&vfio_mm_lock); > > + mmput(mm); > > + return vmm; > > +} > > + > > +/* > > + * Find PASID within @min and @max > > + */ > > +static struct vfio_pasid *vfio_find_pasid(struct vfio_mm *vmm, > > + ioasid_t min, ioasid_t max) > > +{ > > + struct rb_node *node = vmm->pasid_list.rb_node; > > + > > + while (node) { > > + struct vfio_pasid *vid = rb_entry(node, > > + struct vfio_pasid, node); > > + > > + if (max < vid->pasid) > > + node = node->rb_left; > > + else if (min > vid->pasid) > > + node = node->rb_right; > > + else > > + return vid; > > + } > > + > > + return NULL; > > +} > > + > > +static void vfio_link_pasid(struct vfio_mm *vmm, struct vfio_pasid > > +*new) { > > + struct rb_node **link = &vmm->pasid_list.rb_node, *parent = NULL; > > + struct vfio_pasid *vid; > > + > > + while (*link) { > > + parent = *link; > > + vid = rb_entry(parent, struct vfio_pasid, node); > > + > > + if (new->pasid <= vid->pasid) > > + link = &(*link)->rb_left; > > + else > > + link = &(*link)->rb_right; > > + } > > + > > + rb_link_node(&new->node, parent, link); > > + rb_insert_color(&new->node, &vmm->pasid_list); } > > + > > +static void vfio_unlink_pasid(struct vfio_mm *vmm, struct vfio_pasid > > +*old) { > > + rb_erase(&old->node, &vmm->pasid_list); } > > + > > +static void vfio_remove_pasid(struct vfio_mm *vmm, struct vfio_pasid > > +*vid) { > > + vfio_unlink_pasid(vmm, vid); > > + ioasid_free(vid->pasid); > > + kfree(vid); > > +} > > + > > +static void vfio_remove_all_pasids(struct vfio_mm *vmm) { > > + struct rb_node *node; > > + > > + mutex_lock(&vmm->pasid_lock); > > + while ((node = rb_first(&vmm->pasid_list))) > > + vfio_remove_pasid(vmm, rb_entry(node, struct vfio_pasid, node)); > > + mutex_unlock(&vmm->pasid_lock); > > +} > > + > > +int vfio_pasid_alloc(struct vfio_mm *vmm, int min, int max) { > > + ioasid_t pasid; > > + struct vfio_pasid *vid; > > + > > + pasid = ioasid_alloc(vmm->ioasid_sid, min, max, NULL); > > + if (pasid == INVALID_IOASID) > > + return -ENOSPC; > > + > > + vid = kzalloc(sizeof(*vid), GFP_KERNEL); > > + if (!vid) { > > + ioasid_free(pasid); > > + return -ENOMEM; > > + } > > + > > + vid->pasid = pasid; > > + > > + mutex_lock(&vmm->pasid_lock); > > + vfio_link_pasid(vmm, vid); > > + mutex_unlock(&vmm->pasid_lock); > > + > > + return pasid; > > +} > > + > > +void vfio_pasid_free_range(struct vfio_mm *vmm, > > + ioasid_t min, ioasid_t max) > > +{ > > + struct vfio_pasid *vid = NULL; > > + > > + /* > > + * IOASID core will notify PASID users (e.g. IOMMU driver) to > > + * teardown necessary structures depending on the to-be-freed > > + * PASID. > > + */ > > + mutex_lock(&vmm->pasid_lock); > > + while ((vid = vfio_find_pasid(vmm, min, max)) != NULL) > > + vfio_remove_pasid(vmm, vid); > > + mutex_unlock(&vmm->pasid_lock); > > +} > > + > > +static int __init vfio_pasid_init(void) { > > + mutex_init(&vfio_mm_lock); > > + INIT_LIST_HEAD(&vfio_mm_list); > > + return 0; > > +} > > + > > +static void __exit vfio_pasid_exit(void) { > > + /* > > + * VFIO_PASID is supposed to be referenced by VFIO_IOMMU_TYPE1 > > + * and may be other module. once vfio_pasid_exit() is triggered, > > + * that means its user (e.g. VFIO_IOMMU_TYPE1) has been removed. > > + * All the vfio_mm instances should have been released. If not, > > + * means there is vfio_mm leak, should be a bug of user module. > > + * So just warn here. > > + */ > > + WARN_ON(!list_empty(&vfio_mm_list)); > > +} > > + > > +module_init(vfio_pasid_init); > > +module_exit(vfio_pasid_exit); > > + > > +MODULE_VERSION(DRIVER_VERSION); > > +MODULE_LICENSE("GPL v2"); > > +MODULE_AUTHOR(DRIVER_AUTHOR); > > +MODULE_DESCRIPTION(DRIVER_DESC); > > diff --git a/include/linux/vfio.h b/include/linux/vfio.h index > > 38d3c6a..31472a9 100644 > > --- a/include/linux/vfio.h > > +++ b/include/linux/vfio.h > > @@ -97,6 +97,34 @@ extern int vfio_register_iommu_driver(const struct > > vfio_iommu_driver_ops *ops); extern void vfio_unregister_iommu_driver( > > const struct vfio_iommu_driver_ops *ops); > > > > +struct vfio_mm; > > +#if IS_ENABLED(CONFIG_VFIO_PASID) > > +extern struct vfio_mm *vfio_mm_get_from_task(struct task_struct > > +*task); extern void vfio_mm_put(struct vfio_mm *vmm); extern int > > +vfio_pasid_alloc(struct vfio_mm *vmm, int min, int max); extern void > > +vfio_pasid_free_range(struct vfio_mm *vmm, > > + ioasid_t min, ioasid_t max); > > +#else > > +static inline struct vfio_mm *vfio_mm_get_from_task(struct > > +task_struct *task) { > > + return ERR_PTR(-ENOTTY); > > +} > > + > > +static inline void vfio_mm_put(struct vfio_mm *vmm) { } > > + > > +static inline int vfio_pasid_alloc(struct vfio_mm *vmm, int min, int > > +max) { > > + return -ENOTTY; > > +} > > + > > +static inline void vfio_pasid_free_range(struct vfio_mm *vmm, > > + ioasid_t min, ioasid_t max) > > +{ > > +} > > +#endif /* CONFIG_VFIO_PASID */ > > + > > /* > > * External user API > > */ > > > Besides looks good to me > Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx> thanks. :-) Regards, Yi Liu > Thanks > > Eric
