Hi Yi, On 7/20/20 10:03 AM, Liu, Yi L wrote: > Hi Eric, > >> From: Auger Eric <eric.auger@xxxxxxxxxx> >> Sent: Sunday, July 19, 2020 11:39 PM >> >> Yi, >> >> On 7/12/20 1:21 PM, 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 cross all devices, >>> regardless >> across? > > yep. will correct it. > >>> 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> >>> --- >>> 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 | 235 >> ++++++++++++++++++++++++++++++++++++++++++++++ >>> include/linux/vfio.h | 28 ++++++ >>> 4 files changed, 269 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..66e6054e >>> --- /dev/null >>> +++ b/drivers/vfio/vfio_pasid.c >>> @@ -0,0 +1,235 @@ >>> +// 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> >>> +#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)"); >> s/ Set/Set > > got it. > >>> + >>> +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_remove_pasid(struct vfio_mm *vmm, struct vfio_pasid >>> +*vid) { >>> + rb_erase(&vid->node, &vmm->pasid_list); /* unlink pasid */ >> nit: to be consistent with vfio_unlink_dma, introduce vfio_unlink_pasid > > aha, I added it but removed it in the middle of cooking.:-) > >>> + 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; >>> +} >> I am not totally convinced by your previous reply on EXPORT_SYMBOL_GP() >> irrelevance in this patch. But well ;-) > > I recalled my memory, I think it's made per a comment from Chris. > I guess it may make sense to export symbols together with the exact > driver user of it in this patch as well :-) but maybe I misunderstood > him. if yes, I may add the symbol export back in this patch. > > https://lore.kernel.org/linux-iommu/20200331075331.GA26583@xxxxxxxxxxxxx/#t OK I don't know the best practice here. Anyway there is no caller at this stage either. I think you may describe in the commit message the vfio_iommu_type1 will be the eventual user of the exported functions in this module, what are the exact exported functions here. You may also explain the motivation behind creating a separate module. Thanks Eric > >> >>> + >>> +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) { >>> + WARN_ON(!list_empty(&vfio_mm_list)); >>> +} >> In your previous reply, ie. https://lkml.org/lkml/2020/7/7/273 >> you said: >> " >> I guess yes. 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 >> (VFIO_IOMMU_TYPE1) has been removed. Should all the vfio_mm instances should >> have been released. If not, means there is vfio_mm leak, should be a bug of user >> module." >> >> if I am not wrong this dependency is not yet known at this stage of >> the series? I >> would rather add this comment either in the commit message or here. > > make sense, so far it's not known. I can add a comment here. :-) > > Regards, > Yi Liu > >> Thanks >> >> Eric >> >>> + >>> +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 >>> */ >>> >
