On Mon, 27 Jul 2020 23:27:36 -0700 Liu Yi L <yi.l.liu@xxxxxxxxx> wrote: > This patch allows userspace to request PASID allocation/free, e.g. when > serving the request from the guest. > > PASIDs that are not freed by userspace are automatically freed when the > IOASID set is destroyed when process exits. > > 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@xxxxxxxxxx> > Cc: Joerg Roedel <joro@xxxxxxxxxx> > Cc: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> > Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx> > Signed-off-by: Yi Sun <yi.y.sun@xxxxxxxxxxxxxxx> > Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx> > --- > v5 -> v6: > *) address comments from Eric against v5. remove the alloc/free helper. > > v4 -> v5: > *) address comments from Eric Auger. > *) the comments for the PASID_FREE request is addressed in patch 5/15 of > this series. > > v3 -> v4: > *) address comments from v3, except the below comment against the range > of PASID_FREE request. needs more help on it. > "> +if (req.range.min > req.range.max) > > Is it exploitable that a user can spin the kernel for a long time in > the case of a free by calling this with [0, MAX_UINT] regardless of > their actual allocations?" > https://lore.kernel.org/linux-iommu/20200702151832.048b44d1@xxxxxxx/ > > v1 -> v2: > *) move the vfio_mm related code to be a seprate module > *) use a single structure for alloc/free, could support a range of PASIDs > *) fetch vfio_mm at group_attach time instead of at iommu driver open time > --- > drivers/vfio/Kconfig | 1 + > drivers/vfio/vfio_iommu_type1.c | 69 +++++++++++++++++++++++++++++++++++++++++ > drivers/vfio/vfio_pasid.c | 10 ++++++ > include/linux/vfio.h | 6 ++++ > include/uapi/linux/vfio.h | 37 ++++++++++++++++++++++ > 5 files changed, 123 insertions(+) > > diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig > index 3d8a108..95d90c6 100644 > --- a/drivers/vfio/Kconfig > +++ b/drivers/vfio/Kconfig > @@ -2,6 +2,7 @@ > config VFIO_IOMMU_TYPE1 > tristate > depends on VFIO > + select VFIO_PASID if (X86) > default n > > config VFIO_IOMMU_SPAPR_TCE > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index 18ff0c3..ea89c7c 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -76,6 +76,7 @@ struct vfio_iommu { > bool dirty_page_tracking; > bool pinned_page_dirty_scope; > struct iommu_nesting_info *nesting_info; > + struct vfio_mm *vmm; > }; > > struct vfio_domain { > @@ -1937,6 +1938,11 @@ static void vfio_iommu_iova_insert_copy(struct vfio_iommu *iommu, > > static void vfio_iommu_release_nesting_info(struct vfio_iommu *iommu) > { > + if (iommu->vmm) { > + vfio_mm_put(iommu->vmm); > + iommu->vmm = NULL; > + } > + > kfree(iommu->nesting_info); > iommu->nesting_info = NULL; > } > @@ -2071,6 +2077,26 @@ static int vfio_iommu_type1_attach_group(void *iommu_data, > iommu->nesting_info); > if (ret) > goto out_detach; > + > + if (iommu->nesting_info->features & > + IOMMU_NESTING_FEAT_SYSWIDE_PASID) { > + struct vfio_mm *vmm; > + int sid; > + > + vmm = vfio_mm_get_from_task(current); > + if (IS_ERR(vmm)) { > + ret = PTR_ERR(vmm); > + goto out_detach; > + } > + iommu->vmm = vmm; > + > + sid = vfio_mm_ioasid_sid(vmm); > + ret = iommu_domain_set_attr(domain->domain, > + DOMAIN_ATTR_IOASID_SID, > + &sid); > + if (ret) > + goto out_detach; > + } > } > > /* Get aperture info */ > @@ -2859,6 +2885,47 @@ static int vfio_iommu_type1_dirty_pages(struct vfio_iommu *iommu, > return -EINVAL; > } > > +static int vfio_iommu_type1_pasid_request(struct vfio_iommu *iommu, > + unsigned long arg) > +{ > + struct vfio_iommu_type1_pasid_request req; > + unsigned long minsz; > + int ret; > + > + minsz = offsetofend(struct vfio_iommu_type1_pasid_request, range); > + > + if (copy_from_user(&req, (void __user *)arg, minsz)) > + return -EFAULT; > + > + if (req.argsz < minsz || (req.flags & ~VFIO_PASID_REQUEST_MASK)) > + return -EINVAL; > + > + if (req.range.min > req.range.max) > + return -EINVAL; > + > + mutex_lock(&iommu->lock); > + if (!iommu->vmm) { > + mutex_unlock(&iommu->lock); > + return -EOPNOTSUPP; > + } > + > + switch (req.flags & VFIO_PASID_REQUEST_MASK) { > + case VFIO_IOMMU_FLAG_ALLOC_PASID: > + ret = vfio_pasid_alloc(iommu->vmm, req.range.min, > + req.range.max); > + break; > + case VFIO_IOMMU_FLAG_FREE_PASID: > + vfio_pasid_free_range(iommu->vmm, req.range.min, > + req.range.max); > + ret = 0; > + break; > + default: > + ret = -EINVAL; > + } > + mutex_unlock(&iommu->lock); > + return ret; > +} > + > static long vfio_iommu_type1_ioctl(void *iommu_data, > unsigned int cmd, unsigned long arg) > { > @@ -2875,6 +2942,8 @@ static long vfio_iommu_type1_ioctl(void *iommu_data, > return vfio_iommu_type1_unmap_dma(iommu, arg); > case VFIO_IOMMU_DIRTY_PAGES: > return vfio_iommu_type1_dirty_pages(iommu, arg); > + case VFIO_IOMMU_PASID_REQUEST: > + return vfio_iommu_type1_pasid_request(iommu, arg); > default: > return -ENOTTY; > } > diff --git a/drivers/vfio/vfio_pasid.c b/drivers/vfio/vfio_pasid.c > index befcf29..8d0317f 100644 > --- a/drivers/vfio/vfio_pasid.c > +++ b/drivers/vfio/vfio_pasid.c > @@ -61,6 +61,7 @@ void vfio_mm_put(struct vfio_mm *vmm) > { > kref_put_mutex(&vmm->kref, vfio_mm_release, &vfio_mm_lock); > } > +EXPORT_SYMBOL_GPL(vfio_mm_put); > > static void vfio_mm_get(struct vfio_mm *vmm) > { > @@ -114,6 +115,13 @@ struct vfio_mm *vfio_mm_get_from_task(struct task_struct *task) > mmput(mm); > return vmm; > } > +EXPORT_SYMBOL_GPL(vfio_mm_get_from_task); > + > +int vfio_mm_ioasid_sid(struct vfio_mm *vmm) > +{ > + return vmm->ioasid_sid; > +} > +EXPORT_SYMBOL_GPL(vfio_mm_ioasid_sid); > > /* > * Find PASID within @min and @max > @@ -202,6 +210,7 @@ int vfio_pasid_alloc(struct vfio_mm *vmm, int min, int max) > > return pasid; > } > +EXPORT_SYMBOL_GPL(vfio_pasid_alloc); > > void vfio_pasid_free_range(struct vfio_mm *vmm, > ioasid_t min, ioasid_t max) > @@ -218,6 +227,7 @@ void vfio_pasid_free_range(struct vfio_mm *vmm, > vfio_remove_pasid(vmm, vid); > mutex_unlock(&vmm->pasid_lock); > } > +EXPORT_SYMBOL_GPL(vfio_pasid_free_range); > > static int __init vfio_pasid_init(void) > { > diff --git a/include/linux/vfio.h b/include/linux/vfio.h > index 31472a9..a355d01 100644 > --- a/include/linux/vfio.h > +++ b/include/linux/vfio.h > @@ -101,6 +101,7 @@ 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_mm_ioasid_sid(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); > @@ -114,6 +115,11 @@ static inline void vfio_mm_put(struct vfio_mm *vmm) > { > } > > +static inline int vfio_mm_ioasid_sid(struct vfio_mm *vmm) > +{ > + return -ENOTTY; > +} > + > static inline int vfio_pasid_alloc(struct vfio_mm *vmm, int min, int max) > { > return -ENOTTY; > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h > index 0cf3d6d..6d79557 100644 > --- a/include/uapi/linux/vfio.h > +++ b/include/uapi/linux/vfio.h > @@ -1172,6 +1172,43 @@ struct vfio_iommu_type1_dirty_bitmap_get { > > #define VFIO_IOMMU_DIRTY_PAGES _IO(VFIO_TYPE, VFIO_BASE + 17) > > +/** > + * VFIO_IOMMU_PASID_REQUEST - _IOWR(VFIO_TYPE, VFIO_BASE + 18, > + * struct vfio_iommu_type1_pasid_request) > + * > + * PASID (Processor Address Space ID) is a PCIe concept for tagging > + * address spaces in DMA requests. When system-wide PASID allocation > + * is required by the underlying iommu driver (e.g. Intel VT-d), this > + * provides an interface for userspace to request pasid alloc/free > + * for its assigned devices. Userspace should check the availability > + * of this API by checking VFIO_IOMMU_TYPE1_INFO_CAP_NESTING through > + * VFIO_IOMMU_GET_INFO. > + * > + * @flags=VFIO_IOMMU_FLAG_ALLOC_PASID, allocate a single PASID within @range. > + * @flags=VFIO_IOMMU_FLAG_FREE_PASID, free the PASIDs within @range. > + * @range is [min, max], which means both @min and @max are inclusive. > + * ALLOC_PASID and FREE_PASID are mutually exclusive. > + * > + * returns: allocated PASID value on success, -errno on failure for > + * ALLOC_PASID; > + * 0 for FREE_PASID operation; > + */ > +struct vfio_iommu_type1_pasid_request { > + __u32 argsz; > +#define VFIO_IOMMU_FLAG_ALLOC_PASID (1 << 0) > +#define VFIO_IOMMU_FLAG_FREE_PASID (1 << 1) > + __u32 flags; > + struct { > + __u32 min; > + __u32 max; > + } range; > +}; IOCTL(2) Linux Programmer's Manual IOCTL(2) NAME ioctl - control device SYNOPSIS #include <sys/ioctl.h> int ioctl(int fd, unsigned long request, ...); ioctl(2) returns a signed int, how can it support returning a __u32 pasid and -errno? Thanks, Alex > + > +#define VFIO_PASID_REQUEST_MASK (VFIO_IOMMU_FLAG_ALLOC_PASID | \ > + VFIO_IOMMU_FLAG_FREE_PASID) > + > +#define VFIO_IOMMU_PASID_REQUEST _IO(VFIO_TYPE, VFIO_BASE + 18) > + > /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */ > > /*
