Hi Alex, > From: Alex Williamson <alex.williamson@xxxxxxxxxx> > Sent: Friday, August 21, 2020 9:49 AM > > On Fri, 21 Aug 2020 00:37:19 +0000 > "Liu, Yi L" <yi.l.liu@xxxxxxxxx> wrote: > > > Hi Alex, > > > > > From: Alex Williamson <alex.williamson@xxxxxxxxxx> > > > Sent: Friday, August 21, 2020 4:51 AM > > > > > > 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, > > > > yeah, pasid is 20 bits today per PCI spec, so a valid pasid won't use > > full 32 bits, so I used it. perhaps I need to add a field in the data > > struct to return allocated pasid. that may be safer. do you think it > > works? > > AIUI, the pasid is defined as 20 bits, this isn't simply an > implementation issue, right? So perhaps it's ok as is and just needs > some supplemental comments and checking to verify that the desired > pasid range is valid. Thanks, yep. may add some comments. if VFIO ensures the desired pasid range is valid, then the allocated pasid should be valid all the same. :-) Regards, Yi Liu > Alex
