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    SubjectRe: [PATCH v11 01/13] vfio: VFIO_IOMMU_SET_PASID_TABLE
    On Mon, 16 Nov 2020 12:00:18 +0100
    Eric Auger <eric.auger@redhat.com> wrote:

    > From: "Liu, Yi L" <yi.l.liu@linux.intel.com>
    >
    > This patch adds an VFIO_IOMMU_SET_PASID_TABLE ioctl
    > which aims to pass the virtual iommu guest configuration
    > to the host. This latter takes the form of the so-called
    > PASID table.
    >
    > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
    > Signed-off-by: Liu, Yi L <yi.l.liu@linux.intel.com>
    > Signed-off-by: Eric Auger <eric.auger@redhat.com>
    >
    > ---
    > v11 -> v12:
    > - use iommu_uapi_set_pasid_table
    > - check SET and UNSET are not set simultaneously (Zenghui)
    >
    > v8 -> v9:
    > - Merge VFIO_IOMMU_ATTACH/DETACH_PASID_TABLE into a single
    > VFIO_IOMMU_SET_PASID_TABLE ioctl.
    >
    > v6 -> v7:
    > - add a comment related to VFIO_IOMMU_DETACH_PASID_TABLE
    >
    > v3 -> v4:
    > - restore ATTACH/DETACH
    > - add unwind on failure
    >
    > v2 -> v3:
    > - s/BIND_PASID_TABLE/SET_PASID_TABLE
    >
    > v1 -> v2:
    > - s/BIND_GUEST_STAGE/BIND_PASID_TABLE
    > - remove the struct device arg
    > ---
    > drivers/vfio/vfio_iommu_type1.c | 65 +++++++++++++++++++++++++++++++++
    > include/uapi/linux/vfio.h | 19 ++++++++++
    > 2 files changed, 84 insertions(+)
    >
    > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
    > index 67e827638995..87ddd9e882dc 100644
    > --- a/drivers/vfio/vfio_iommu_type1.c
    > +++ b/drivers/vfio/vfio_iommu_type1.c
    > @@ -2587,6 +2587,41 @@ static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu,
    > return ret;
    > }
    >
    > +static void
    > +vfio_detach_pasid_table(struct vfio_iommu *iommu)
    > +{
    > + struct vfio_domain *d;
    > +
    > + mutex_lock(&iommu->lock);
    > + list_for_each_entry(d, &iommu->domain_list, next)
    > + iommu_detach_pasid_table(d->domain);
    > +
    > + mutex_unlock(&iommu->lock);
    > +}
    > +
    > +static int
    > +vfio_attach_pasid_table(struct vfio_iommu *iommu, unsigned long arg)
    > +{
    > + struct vfio_domain *d;
    > + int ret = 0;
    > +
    > + mutex_lock(&iommu->lock);
    > +
    > + list_for_each_entry(d, &iommu->domain_list, next) {
    > + ret = iommu_uapi_attach_pasid_table(d->domain, (void __user *)arg);
    > + if (ret)
    > + goto unwind;
    > + }
    > + goto unlock;
    > +unwind:
    > + list_for_each_entry_continue_reverse(d, &iommu->domain_list, next) {
    > + iommu_detach_pasid_table(d->domain);
    > + }
    > +unlock:

    This goto leap frog could be avoided with just:

    list_for_each_entry(d, &iommu->domain_list, next) {
    ret = iommu_uapi_attach_pasid_table(d->domain, (void __user *)arg);
    if (ret) {
    list_for_each_entry_continue_reverse(d, &iommu->domain_list, next) {
    iommu_detach_pasid_table(d->domain);
    }
    break;
    }
    }

    > + mutex_unlock(&iommu->lock);
    > + return ret;
    > +}
    > +
    > static int vfio_iommu_migration_build_caps(struct vfio_iommu *iommu,
    > struct vfio_info_cap *caps)
    > {
    > @@ -2747,6 +2782,34 @@ static int vfio_iommu_type1_unmap_dma(struct vfio_iommu *iommu,
    > -EFAULT : 0;
    > }
    >
    > +static int vfio_iommu_type1_set_pasid_table(struct vfio_iommu *iommu,
    > + unsigned long arg)
    > +{
    > + struct vfio_iommu_type1_set_pasid_table spt;
    > + unsigned long minsz;
    > + int ret = -EINVAL;
    > +
    > + minsz = offsetofend(struct vfio_iommu_type1_set_pasid_table, flags);
    > +
    > + if (copy_from_user(&spt, (void __user *)arg, minsz))
    > + return -EFAULT;
    > +
    > + if (spt.argsz < minsz)
    > + return -EINVAL;
    > +
    > + if (spt.flags & VFIO_PASID_TABLE_FLAG_SET &&
    > + spt.flags & VFIO_PASID_TABLE_FLAG_UNSET)
    > + return -EINVAL;
    > +
    > + if (spt.flags & VFIO_PASID_TABLE_FLAG_SET)
    > + ret = vfio_attach_pasid_table(iommu, arg + minsz);
    > + else if (spt.flags & VFIO_PASID_TABLE_FLAG_UNSET) {
    > + vfio_detach_pasid_table(iommu);
    > + ret = 0;
    > + }

    This doesn't really validate that the other flag bits are zero, ex.
    user could pass flags = (1 << 8) | VFIO_PASID_TABLE_FLAG_SET and we'd
    just ignore the extra bit. So this probably needs to be:

    if (spt.flags == VFIO_PASID_TABLE_FLAG_SET)
    ret = vfio_attach_pasid_table(iommu, arg + minsz);
    else if (spt.flags == VFIO_PASID_TABLE_FLAG_UNSET)
    vfio_detach_pasid_table(iommu);

    Or otherwise validate that none of the other bits are set. It also
    seems cleaner to me to set the initial value of ret = 0 and end this
    with:

    else
    ret = -EINVAL;


    > + return ret;
    > +}
    > +
    > static int vfio_iommu_type1_dirty_pages(struct vfio_iommu *iommu,
    > unsigned long arg)
    > {
    > @@ -2867,6 +2930,8 @@ 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_SET_PASID_TABLE:
    > + return vfio_iommu_type1_set_pasid_table(iommu, arg);
    > default:
    > return -ENOTTY;
    > }
    > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
    > index 2f313a238a8f..78ce3ce6c331 100644
    > --- a/include/uapi/linux/vfio.h
    > +++ b/include/uapi/linux/vfio.h
    > @@ -14,6 +14,7 @@
    >
    > #include <linux/types.h>
    > #include <linux/ioctl.h>
    > +#include <linux/iommu.h>
    >
    > #define VFIO_API_VERSION 0
    >
    > @@ -1180,6 +1181,24 @@ struct vfio_iommu_type1_dirty_bitmap_get {
    >
    > #define VFIO_IOMMU_DIRTY_PAGES _IO(VFIO_TYPE, VFIO_BASE + 17)
    >
    > +/*
    > + * VFIO_IOMMU_SET_PASID_TABLE - _IOWR(VFIO_TYPE, VFIO_BASE + 22,

    We already reuse ioctl indexes between type1 and spapr (ex. +17 is
    either VFIO_IOMMU_DIRTY_PAGES or VFIO_IOMMU_SPAPR_REGISTER_MEMORY
    depending on the iommu type). I wonder if we should reuse +18 here
    instead.

    > + * struct vfio_iommu_type1_set_pasid_table)
    > + *
    > + * The SET operation passes a PASID table to the host while the
    > + * UNSET operation detaches the one currently programmed. Setting
    > + * a table while another is already programmed replaces the old table.
    > + */
    > +struct vfio_iommu_type1_set_pasid_table {
    > + __u32 argsz;
    > + __u32 flags;
    > +#define VFIO_PASID_TABLE_FLAG_SET (1 << 0)
    > +#define VFIO_PASID_TABLE_FLAG_UNSET (1 << 1)
    > + struct iommu_pasid_table_config config; /* used on SET */
    > +};
    > +
    > +#define VFIO_IOMMU_SET_PASID_TABLE _IO(VFIO_TYPE, VFIO_BASE + 22)
    > +
    > /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
    >
    > /*

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