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    SubjectRe: [PATCH v6 08/22] vfio: VFIO_IOMMU_CACHE_INVALIDATE
    On Sun, 17 Mar 2019 18:22:18 +0100
    Eric Auger <eric.auger@redhat.com> wrote:

    > From: "Liu, Yi L" <yi.l.liu@linux.intel.com>
    >
    > When the guest "owns" the stage 1 translation structures, the host
    > IOMMU driver has no knowledge of caching structure updates unless
    > the guest invalidation requests are trapped and passed down to the
    > host.
    >
    > This patch adds the VFIO_IOMMU_CACHE_INVALIDATE ioctl with aims
    > at propagating guest stage1 IOMMU cache invalidations to the host.
    >
    > Signed-off-by: Liu, Yi L <yi.l.liu@linux.intel.com>
    > Signed-off-by: Eric Auger <eric.auger@redhat.com>
    >
    > ---
    >
    > v2 -> v3:
    > - introduce vfio_iommu_for_each_dev back in this patch
    >
    > v1 -> v2:
    > - s/TLB/CACHE
    > - remove vfio_iommu_task usage
    > - commit message rewording
    > ---
    > drivers/vfio/vfio_iommu_type1.c | 47 +++++++++++++++++++++++++++++++++
    > include/uapi/linux/vfio.h | 13 +++++++++
    > 2 files changed, 60 insertions(+)
    >
    > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
    > index 222e9199edbf..12a40b9db6aa 100644
    > --- a/drivers/vfio/vfio_iommu_type1.c
    > +++ b/drivers/vfio/vfio_iommu_type1.c
    > @@ -113,6 +113,26 @@ struct vfio_regions {
    > #define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu) \
    > (!list_empty(&iommu->domain_list))
    >

    static struct foo {
    struct iommu_domain *domain;
    void *data;
    };

    > +/* iommu->lock must be held */
    > +static int
    > +vfio_iommu_for_each_dev(struct vfio_iommu *iommu, void *data,
    > + int (*fn)(struct device *, void *))
    > +{
    > + struct vfio_domain *d;
    > + struct vfio_group *g;
    > + int ret = 0;

    struct foo bar = { .data = data };

    > +
    > + list_for_each_entry(d, &iommu->domain_list, next) {

    bar.domain = d->domain;

    > + list_for_each_entry(g, &d->group_list, next) {
    > + ret = iommu_group_for_each_dev(g->iommu_group,
    > + data, fn);

    s/data/&bar/

    > + if (ret)
    > + break;
    > + }
    > + }
    > + return ret;
    > +}
    > +
    > static int put_pfn(unsigned long pfn, int prot);
    >
    > /*
    > @@ -1681,6 +1701,15 @@ vfio_attach_pasid_table(struct vfio_iommu *iommu,
    > return ret;
    > }
    >
    > +static int vfio_cache_inv_fn(struct device *dev, void *data)
    > +{

    struct foo *bar = data;

    > + struct vfio_iommu_type1_cache_invalidate *ustruct =
    > + (struct vfio_iommu_type1_cache_invalidate *)data;

    ... = bar->data;

    > + struct iommu_domain *d = iommu_get_domain_for_dev(dev);

    ... = bar->domain;

    ¯\_(ツ)_/¯ seems more efficient that doing a lookup.
    > +
    > + return iommu_cache_invalidate(d, dev, &ustruct->info);
    > +}
    > +
    > static long vfio_iommu_type1_ioctl(void *iommu_data,
    > unsigned int cmd, unsigned long arg)
    > {
    > @@ -1767,6 +1796,24 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
    > } else if (cmd == VFIO_IOMMU_DETACH_PASID_TABLE) {
    > vfio_detach_pasid_table(iommu);
    > return 0;
    > + } else if (cmd == VFIO_IOMMU_CACHE_INVALIDATE) {
    > + struct vfio_iommu_type1_cache_invalidate ustruct;
    > + int ret;
    > +
    > + minsz = offsetofend(struct vfio_iommu_type1_cache_invalidate,
    > + info);
    > +
    > + if (copy_from_user(&ustruct, (void __user *)arg, minsz))
    > + return -EFAULT;
    > +
    > + if (ustruct.argsz < minsz || ustruct.flags)
    > + return -EINVAL;
    > +
    > + mutex_lock(&iommu->lock);
    > + ret = vfio_iommu_for_each_dev(iommu, &ustruct,
    > + vfio_cache_inv_fn);

    Guess what has a version field that never gets checked ;)

    Thanks,
    Alex

    > + mutex_unlock(&iommu->lock);
    > + return ret;
    > }
    >
    > return -ENOTTY;
    > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
    > index 329d378565d9..29f0ef2d805d 100644
    > --- a/include/uapi/linux/vfio.h
    > +++ b/include/uapi/linux/vfio.h
    > @@ -776,6 +776,19 @@ struct vfio_iommu_type1_attach_pasid_table {
    > #define VFIO_IOMMU_ATTACH_PASID_TABLE _IO(VFIO_TYPE, VFIO_BASE + 22)
    > #define VFIO_IOMMU_DETACH_PASID_TABLE _IO(VFIO_TYPE, VFIO_BASE + 23)
    >
    > +/**
    > + * VFIO_IOMMU_CACHE_INVALIDATE - _IOWR(VFIO_TYPE, VFIO_BASE + 24,
    > + * struct vfio_iommu_type1_cache_invalidate)
    > + *
    > + * Propagate guest IOMMU cache invalidation to the host.
    > + */
    > +struct vfio_iommu_type1_cache_invalidate {
    > + __u32 argsz;
    > + __u32 flags;
    > + struct iommu_cache_invalidate_info info;
    > +};
    > +#define VFIO_IOMMU_CACHE_INVALIDATE _IO(VFIO_TYPE, VFIO_BASE + 24)
    > +
    > /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
    >
    > /*

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