From: Alex Williamson <alex.williamson@redhat.com>
To: Liu Yi L <yi.l.liu@intel.com>
Cc: jean-philippe@linaro.org, kevin.tian@intel.com,
ashok.raj@intel.com, kvm@vger.kernel.org, stefanha@gmail.com,
iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
yi.y.sun@intel.com, hao.wu@intel.com, jun.j.tian@intel.com
Subject: Re: [PATCH v6 07/15] vfio/type1: Add VFIO_IOMMU_PASID_REQUEST (alloc/free)
Date: Thu, 20 Aug 2020 14:51:27 -0600 [thread overview]
Message-ID: <20200820145127.61ed8727@x1.home> (raw)
In-Reply-To: <1595917664-33276-8-git-send-email-yi.l.liu@intel.com>
On Mon, 27 Jul 2020 23:27:36 -0700
Liu Yi L <yi.l.liu@intel.com> 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@intel.com>
> CC: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Cc: Eric Auger <eric.auger@redhat.com>
> Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Lu Baolu <baolu.lu@linux.intel.com>
> Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
> 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@x1.home/
>
> 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 -------- */
>
> /*
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next prev parent reply other threads:[~2020-08-20 20:51 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-28 6:27 [PATCH v6 00/15] vfio: expose virtual Shared Virtual Addressing to VMs Liu Yi L
2020-07-28 6:27 ` [PATCH v6 01/15] vfio/type1: Refactor vfio_iommu_type1_ioctl() Liu Yi L
2020-07-28 15:53 ` Alex Williamson
2020-07-29 2:20 ` Liu, Yi L
2020-07-28 6:27 ` [PATCH v6 02/15] iommu: Report domain nesting info Liu Yi L
2020-08-13 12:52 ` Auger Eric
2020-08-14 7:15 ` Liu, Yi L
2020-08-16 12:40 ` Auger Eric
2020-08-18 4:21 ` Jacob Pan
2020-08-18 6:59 ` Auger Eric
2020-07-28 6:27 ` [PATCH v6 03/15] iommu/smmu: Report empty " Liu Yi L
2020-07-28 6:27 ` [PATCH v6 04/15] vfio/type1: Report iommu nesting info to userspace Liu Yi L
2020-08-13 13:19 ` Auger Eric
2020-08-14 7:36 ` Liu, Yi L
2020-08-20 19:52 ` Alex Williamson
2020-08-21 0:52 ` Liu, Yi L
2020-07-28 6:27 ` [PATCH v6 05/15] vfio: Add PASID allocation/free support Liu Yi L
2020-08-13 15:07 ` Auger Eric
2020-08-14 7:40 ` Liu, Yi L
2020-07-28 6:27 ` [PATCH v6 06/15] iommu/vt-d: Support setting ioasid set to domain Liu Yi L
2020-08-13 15:06 ` Auger Eric
2020-08-14 8:04 ` Liu, Yi L
2020-08-16 12:42 ` Auger Eric
2020-07-28 6:27 ` [PATCH v6 07/15] vfio/type1: Add VFIO_IOMMU_PASID_REQUEST (alloc/free) Liu Yi L
2020-08-15 16:30 ` Auger Eric
2020-08-17 5:23 ` Liu, Yi L
2020-08-20 20:51 ` Alex Williamson [this message]
2020-08-21 0:37 ` Liu, Yi L
2020-08-21 1:49 ` Alex Williamson
2020-08-21 2:18 ` Liu, Yi L
2020-07-28 6:27 ` [PATCH v6 08/15] iommu: Pass domain to sva_unbind_gpasid() Liu Yi L
2020-08-20 21:06 ` Alex Williamson
2020-08-21 0:18 ` Liu, Yi L
2020-08-21 13:09 ` Auger Eric
2020-07-28 6:27 ` [PATCH v6 09/15] iommu/vt-d: Check ownership for PASIDs from user-space Liu Yi L
2020-08-15 16:30 ` Auger Eric
2020-08-17 5:38 ` Liu, Yi L
2020-07-28 6:27 ` [PATCH v6 10/15] vfio/type1: Support binding guest page tables to PASID Liu Yi L
2020-08-16 11:29 ` Auger Eric
2020-08-17 6:30 ` Liu, Yi L
2020-07-28 6:27 ` [PATCH v6 11/15] vfio/type1: Allow invalidating first-level/stage IOMMU cache Liu Yi L
2020-08-16 11:35 ` Auger Eric
2020-08-17 6:30 ` Liu, Yi L
2020-07-28 6:27 ` [PATCH v6 12/15] vfio/type1: Add vSVA support for IOMMU-backed mdevs Liu Yi L
2020-08-20 21:48 ` Alex Williamson
2020-08-21 0:53 ` Liu, Yi L
2020-07-28 6:27 ` [PATCH v6 13/15] vfio/pci: Expose PCIe PASID capability to guest Liu Yi L
2020-07-28 6:27 ` [PATCH v6 14/15] vfio: Document dual stage control Liu Yi L
2020-08-16 11:51 ` Auger Eric
2020-08-17 7:00 ` Liu, Yi L
2020-08-17 7:40 ` Eric Auger
2020-08-17 7:43 ` Liu, Yi L
2020-07-28 6:27 ` [PATCH v6 15/15] iommu/vt-d: Support reporting nesting capability info Liu Yi L
2020-08-16 12:01 ` Auger Eric
2020-08-17 7:05 ` Liu, Yi L
2020-08-17 7:42 ` Auger Eric
2020-08-17 7:45 ` Liu, Yi L
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