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    Subject[PATCH v2 25/30] vfio-pci/zdev: wire up zPCI interpretive execution support
    Date
    Introduce support for VFIO_DEVICE_FEATURE_ZPCI_INTERP, which is a new
    VFIO_DEVICE_FEATURE ioctl. This interface is used to indicate that an
    s390x vfio-pci device wishes to enable/disable zPCI interpretive
    execution, which allows zPCI instructions to be executed directly by
    underlying firmware without KVM involvement.

    Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
    ---
    arch/s390/include/asm/kvm_pci.h | 1 +
    drivers/vfio/pci/vfio_pci_core.c | 2 +
    drivers/vfio/pci/vfio_pci_zdev.c | 78 ++++++++++++++++++++++++++++++++
    include/linux/vfio_pci_core.h | 10 ++++
    include/uapi/linux/vfio.h | 7 +++
    include/uapi/linux/vfio_zdev.h | 15 ++++++
    6 files changed, 113 insertions(+)

    diff --git a/arch/s390/include/asm/kvm_pci.h b/arch/s390/include/asm/kvm_pci.h
    index 97a90b37c87d..dc00c3f27a00 100644
    --- a/arch/s390/include/asm/kvm_pci.h
    +++ b/arch/s390/include/asm/kvm_pci.h
    @@ -35,6 +35,7 @@ struct kvm_zdev {
    struct kvm_zdev_ioat ioat;
    struct zpci_fib fib;
    struct notifier_block nb;
    + bool interp;
    };

    int kvm_s390_pci_dev_open(struct zpci_dev *zdev);
    diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
    index fc57d4d0abbe..2b2d64a2190c 100644
    --- a/drivers/vfio/pci/vfio_pci_core.c
    +++ b/drivers/vfio/pci/vfio_pci_core.c
    @@ -1172,6 +1172,8 @@ long vfio_pci_core_ioctl(struct vfio_device *core_vdev, unsigned int cmd,
    mutex_unlock(&vdev->vf_token->lock);

    return 0;
    + case VFIO_DEVICE_FEATURE_ZPCI_INTERP:
    + return vfio_pci_zdev_feat_interp(vdev, feature, arg);
    default:
    return -ENOTTY;
    }
    diff --git a/drivers/vfio/pci/vfio_pci_zdev.c b/drivers/vfio/pci/vfio_pci_zdev.c
    index 5c2bddc57b39..4339f48b98bc 100644
    --- a/drivers/vfio/pci/vfio_pci_zdev.c
    +++ b/drivers/vfio/pci/vfio_pci_zdev.c
    @@ -54,6 +54,10 @@ static int zpci_group_cap(struct zpci_dev *zdev, struct vfio_info_cap *caps)
    .version = zdev->version
    };

    + /* Some values are different for interpreted devices */
    + if (zdev->kzdev && zdev->kzdev->interp)
    + cap.maxstbl = zdev->maxstbl;
    +
    return vfio_info_add_capability(caps, &cap.header, sizeof(cap));
    }

    @@ -138,6 +142,72 @@ int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev,
    return ret;
    }

    +int vfio_pci_zdev_feat_interp(struct vfio_pci_core_device *vdev,
    + struct vfio_device_feature feature,
    + unsigned long arg)
    +{
    + struct zpci_dev *zdev = to_zpci(vdev->pdev);
    + struct vfio_device_zpci_interp *data;
    + struct vfio_device_feature *feat;
    + unsigned long minsz;
    + int size, rc;
    +
    + if (!zdev || !zdev->kzdev)
    + return -EINVAL;
    +
    + /* If PROBE specified, return probe results immediately */
    + if (feature.flags & VFIO_DEVICE_FEATURE_PROBE)
    + return kvm_s390_pci_interp_probe(zdev);
    +
    + /* GET and SET are mutually exclusive */
    + if ((feature.flags & VFIO_DEVICE_FEATURE_GET) &&
    + (feature.flags & VFIO_DEVICE_FEATURE_SET))
    + return -EINVAL;
    +
    + size = sizeof(*feat) + sizeof(*data);
    + feat = kzalloc(size, GFP_KERNEL);
    + if (!feat)
    + return -ENOMEM;
    +
    + data = (struct vfio_device_zpci_interp *)&feat->data;
    + minsz = offsetofend(struct vfio_device_feature, flags);
    +
    + if (feature.argsz < minsz + sizeof(*data))
    + return -EINVAL;
    +
    + /* Get the rest of the payload for GET/SET */
    + rc = copy_from_user(data, (void __user *)(arg + minsz),
    + sizeof(*data));
    + if (rc)
    + rc = -EINVAL;
    +
    + if (feature.flags & VFIO_DEVICE_FEATURE_GET) {
    + if (zdev->gd != 0)
    + data->flags = VFIO_DEVICE_ZPCI_FLAG_INTERP;
    + else
    + data->flags = 0;
    + data->fh = zdev->fh;
    + /* userspace is using host fh, give interpreted clp values */
    + zdev->kzdev->interp = true;
    +
    + if (copy_to_user((void __user *)arg, feat, size))
    + rc = -EFAULT;
    + } else if (feature.flags & VFIO_DEVICE_FEATURE_SET) {
    + if (data->flags == VFIO_DEVICE_ZPCI_FLAG_INTERP)
    + rc = kvm_s390_pci_interp_enable(zdev);
    + else if (data->flags == 0)
    + rc = kvm_s390_pci_interp_disable(zdev);
    + else
    + rc = -EINVAL;
    + } else {
    + /* Neither GET nor SET were specified */
    + rc = -EINVAL;
    + }
    +
    + kfree(feat);
    + return rc;
    +}
    +
    static int vfio_pci_zdev_group_notifier(struct notifier_block *nb,
    unsigned long action, void *data)
    {
    @@ -164,6 +234,7 @@ void vfio_pci_zdev_open(struct vfio_pci_core_device *vdev)
    return;

    zdev->kzdev->nb.notifier_call = vfio_pci_zdev_group_notifier;
    + zdev->kzdev->interp = false;

    if (vfio_register_notifier(vdev->vdev.dev, VFIO_GROUP_NOTIFY,
    &events, &zdev->kzdev->nb))
    @@ -180,5 +251,12 @@ void vfio_pci_zdev_release(struct vfio_pci_core_device *vdev)
    vfio_unregister_notifier(vdev->vdev.dev, VFIO_GROUP_NOTIFY,
    &zdev->kzdev->nb);

    + /*
    + * If the device was using interpretation, don't trust that userspace
    + * did the appropriate cleanup
    + */
    + if (zdev->gd != 0)
    + kvm_s390_pci_interp_disable(zdev);
    +
    kvm_s390_pci_dev_release(zdev);
    }
    diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
    index 05287f8ac855..0db2b1051931 100644
    --- a/include/linux/vfio_pci_core.h
    +++ b/include/linux/vfio_pci_core.h
    @@ -198,6 +198,9 @@ static inline int vfio_pci_igd_init(struct vfio_pci_core_device *vdev)
    #ifdef CONFIG_VFIO_PCI_ZDEV
    extern int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev,
    struct vfio_info_cap *caps);
    +int vfio_pci_zdev_feat_interp(struct vfio_pci_core_device *vdev,
    + struct vfio_device_feature feature,
    + unsigned long arg);
    void vfio_pci_zdev_open(struct vfio_pci_core_device *vdev);
    void vfio_pci_zdev_release(struct vfio_pci_core_device *vdev);
    #else
    @@ -207,6 +210,13 @@ static inline int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev,
    return -ENODEV;
    }

    +static inline int vfio_pci_zdev_feat_interp(struct vfio_pci_core_device *vdev,
    + struct vfio_device_feature feature,
    + unsigned long arg)
    +{
    + return -ENOTTY;
    +}
    +
    static inline void vfio_pci_zdev_open(struct vfio_pci_core_device *vdev)
    {
    }
    diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
    index ef33ea002b0b..b9a75485b8e7 100644
    --- a/include/uapi/linux/vfio.h
    +++ b/include/uapi/linux/vfio.h
    @@ -1002,6 +1002,13 @@ struct vfio_device_feature {
    */
    #define VFIO_DEVICE_FEATURE_PCI_VF_TOKEN (0)

    +/*
    + * Provide support for enabling interpretation of zPCI instructions. This
    + * feature is only valid for s390x PCI devices. Data provided when setting
    + * and getting this feature is futher described in vfio_zdev.h
    + */
    +#define VFIO_DEVICE_FEATURE_ZPCI_INTERP (1)
    +
    /* -------- API for Type1 VFIO IOMMU -------- */

    /**
    diff --git a/include/uapi/linux/vfio_zdev.h b/include/uapi/linux/vfio_zdev.h
    index b4309397b6b2..575f0410dc66 100644
    --- a/include/uapi/linux/vfio_zdev.h
    +++ b/include/uapi/linux/vfio_zdev.h
    @@ -75,4 +75,19 @@ struct vfio_device_info_cap_zpci_pfip {
    __u8 pfip[];
    };

    +/**
    + * VFIO_DEVICE_FEATURE_ZPCI_INTERP
    + *
    + * This feature is used for enabling zPCI instruction interpretation for a
    + * device. No data is provided when setting this feature. When getting
    + * this feature, the following structure is provided which details whether
    + * or not interpretation is active and provides the guest with host device
    + * information necessary to enable interpretation.
    + */
    +struct vfio_device_zpci_interp {
    + __u64 flags;
    +#define VFIO_DEVICE_ZPCI_FLAG_INTERP 1
    + __u32 fh; /* Host device function handle */
    +};
    +
    #endif
    --
    2.27.0
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