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    SubjectRe: [PATCH v2 27/30] vfio-pci/zdev: wire up zPCI IOAT assist support
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    On 1/14/22 21:31, Matthew Rosato wrote:
    > Introduce support for VFIO_DEVICE_FEATURE_ZPCI_IOAT, 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 I/O Address
    > Translation assistance, allowing the host to perform address translation
    > and shadowing.
    >

    Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>


    > 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 | 63 ++++++++++++++++++++++++++++++++
    > include/linux/vfio_pci_core.h | 10 +++++
    > include/uapi/linux/vfio.h | 8 ++++
    > include/uapi/linux/vfio_zdev.h | 13 +++++++
    > 6 files changed, 97 insertions(+)
    >
    > diff --git a/arch/s390/include/asm/kvm_pci.h b/arch/s390/include/asm/kvm_pci.h
    > index dbab349a4a75..7b6b6d771026 100644
    > --- a/arch/s390/include/asm/kvm_pci.h
    > +++ b/arch/s390/include/asm/kvm_pci.h
    > @@ -32,6 +32,7 @@ struct kvm_zdev {
    > struct zpci_dev *zdev;
    > struct kvm *kvm;
    > u64 rpcit_count;
    > + u64 iota;
    > struct kvm_zdev_ioat ioat;
    > struct zpci_fib fib;
    > struct notifier_block nb;
    > diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
    > index 01658de660bd..709d9ba22a60 100644
    > --- a/drivers/vfio/pci/vfio_pci_core.c
    > +++ b/drivers/vfio/pci/vfio_pci_core.c
    > @@ -1176,6 +1176,8 @@ long vfio_pci_core_ioctl(struct vfio_device *core_vdev, unsigned int cmd,
    > return vfio_pci_zdev_feat_interp(vdev, feature, arg);
    > case VFIO_DEVICE_FEATURE_ZPCI_AIF:
    > return vfio_pci_zdev_feat_aif(vdev, feature, arg);
    > + case VFIO_DEVICE_FEATURE_ZPCI_IOAT:
    > + return vfio_pci_zdev_feat_ioat(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 891cfa016d63..2b169d688937 100644
    > --- a/drivers/vfio/pci/vfio_pci_zdev.c
    > +++ b/drivers/vfio/pci/vfio_pci_zdev.c
    > @@ -302,6 +302,68 @@ int vfio_pci_zdev_feat_aif(struct vfio_pci_core_device *vdev,
    > return rc;
    > }
    >
    > +int vfio_pci_zdev_feat_ioat(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_ioat *data;

    NIT: something more explicit than "data" like "ioat_feature" ?

    > + struct vfio_device_feature *feat;
    > + unsigned long minsz;
    > + int size, rc = 0;
    > +
    > + if (!zdev || !zdev->kzdev)
    > + return -EINVAL;
    > +
    > + /* If PROBE specified, return probe results immediately */
    > + if (feature.flags & VFIO_DEVICE_FEATURE_PROBE)
    > + return kvm_s390_pci_ioat_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_ioat *)&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) {
    > + data->iota = (u64)zdev->kzdev->iota;
    > + if (copy_to_user((void __user *)arg, feat, size))
    > + rc = -EFAULT;
    > + } else if (feature.flags & VFIO_DEVICE_FEATURE_SET) {
    > + if (data->iota != 0) {
    > + rc = kvm_s390_pci_ioat_enable(zdev, data->iota);
    > + if (!rc)
    > + zdev->kzdev->iota = data->iota;
    > + } else if (zdev->kzdev->iota != 0) {
    > + rc = kvm_s390_pci_ioat_disable(zdev);
    > + if (!rc)
    > + zdev->kzdev->iota = 0;
    > + }
    > + } 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)
    > {
    > @@ -351,6 +413,7 @@ void vfio_pci_zdev_release(struct vfio_pci_core_device *vdev)
    > */
    > if (zdev->gd != 0) {
    > kvm_s390_pci_aif_disable(zdev);
    > + kvm_s390_pci_ioat_disable(zdev);
    > kvm_s390_pci_interp_disable(zdev);
    > }
    >
    > diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
    > index 7ec5e82e7933..f17d761ae14e 100644
    > --- a/include/linux/vfio_pci_core.h
    > +++ b/include/linux/vfio_pci_core.h
    > @@ -204,6 +204,9 @@ int vfio_pci_zdev_feat_interp(struct vfio_pci_core_device *vdev,
    > int vfio_pci_zdev_feat_aif(struct vfio_pci_core_device *vdev,
    > struct vfio_device_feature feature,
    > unsigned long arg);
    > +int vfio_pci_zdev_feat_ioat(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
    > @@ -227,6 +230,13 @@ static inline int vfio_pci_zdev_feat_aif(struct vfio_pci_core_device *vdev,
    > return -ENOTTY;
    > }
    >
    > +static inline int vfio_pci_zdev_feat_ioat(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 fe3bfd99bf50..32c687388f48 100644
    > --- a/include/uapi/linux/vfio.h
    > +++ b/include/uapi/linux/vfio.h
    > @@ -1016,6 +1016,14 @@ struct vfio_device_feature {
    > */
    > #define VFIO_DEVICE_FEATURE_ZPCI_AIF (2)
    >
    > +/*
    > + * Provide support for enabling guest I/O address translation assistance for
    > + * zPCI devices. This feature is only valid for s390x PCI devices. Data
    > + * provided when setting and getting this feature is further described in
    > + * vfio_zdev.h
    > + */
    > +#define VFIO_DEVICE_FEATURE_ZPCI_IOAT (3)
    > +
    > /* -------- API for Type1 VFIO IOMMU -------- */
    >
    > /**
    > diff --git a/include/uapi/linux/vfio_zdev.h b/include/uapi/linux/vfio_zdev.h
    > index c574e23f9385..1a5229b7bb18 100644
    > --- a/include/uapi/linux/vfio_zdev.h
    > +++ b/include/uapi/linux/vfio_zdev.h
    > @@ -110,4 +110,17 @@ struct vfio_device_zpci_aif {
    > __u8 sbo; /* Offset of guest summary bit vector */
    > };
    >
    > +/**
    > + * VFIO_DEVICE_FEATURE_ZPCI_IOAT
    > + *
    > + * This feature is used for enabling guest I/O translation assistance for
    > + * passthrough zPCI devices using instruction interpretation. When setting
    > + * this feature, the iota specifies a KVM guest I/O translation anchor. When
    > + * getting this feature, the most recently set anchor (or 0) is returned in
    > + * iota.
    > + */
    > +struct vfio_device_zpci_ioat {
    > + __u64 iota;
    > +};
    > +
    > #endif
    >

    --
    Pierre Morel
    IBM Lab Boeblingen

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