Re: [PATCH 28/32] vfio-pci/zdev: wire up zPCI adapter interrupt forwarding support

Pierre Morel
2021-12-14T09:47:51Z

On 12/7/21 21:57, Matthew Rosato wrote:
> Introduce support for VFIO_DEVICE_FEATURE_ZPCI_AIF, 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 adapter interrupt
> forwarding, which allows underlying firmware to deliver interrupts
> directly to the associated kvm guest.
>
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> ---
> arch/s390/include/asm/kvm_pci.h | 2 +
> drivers/vfio/pci/vfio_pci_core.c | 2 +
> drivers/vfio/pci/vfio_pci_zdev.c | 96 +++++++++++++++++++++++++++++++-
> include/linux/vfio_pci_core.h | 10 ++++
> include/uapi/linux/vfio.h | 7 +++
> include/uapi/linux/vfio_zdev.h | 20 +++++++
> 6 files changed, 136 insertions(+), 1 deletion(-)
>
> diff --git a/arch/s390/include/asm/kvm_pci.h b/arch/s390/include/asm/kvm_pci.h
> index 062bac720428..0a0e42e1db1c 100644
> --- a/arch/s390/include/asm/kvm_pci.h
> +++ b/arch/s390/include/asm/kvm_pci.h
> @@ -36,6 +36,8 @@ struct kvm_zdev {
> struct zpci_fib fib;
> struct notifier_block nb;
> bool interp;
> + bool aif;
> + bool fhost;
> };
>
> extern 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 2b2d64a2190c..01658de660bd 100644
> --- a/drivers/vfio/pci/vfio_pci_core.c
> +++ b/drivers/vfio/pci/vfio_pci_core.c
> @@ -1174,6 +1174,8 @@ long vfio_pci_core_ioctl(struct vfio_device *core_vdev, unsigned int cmd,
> return 0;
> case VFIO_DEVICE_FEATURE_ZPCI_INTERP:
> return vfio_pci_zdev_feat_interp(vdev, feature, arg);
> + case VFIO_DEVICE_FEATURE_ZPCI_AIF:
> + return vfio_pci_zdev_feat_aif(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 b205e0ad1fd3..dd98808b9139 100644
> --- a/drivers/vfio/pci/vfio_pci_zdev.c
> +++ b/drivers/vfio/pci/vfio_pci_zdev.c
> @@ -13,6 +13,7 @@
> #include <linux/vfio_zdev.h>
> #include <asm/pci_clp.h>
> #include <asm/pci_io.h>
> +#include <asm/pci_insn.h>
> #include <asm/kvm_pci.h>
>
> #include <linux/vfio_pci_core.h>
> @@ -206,6 +207,97 @@ int vfio_pci_zdev_feat_interp(struct vfio_pci_core_device *vdev,
> return rc;
> }
>
> +int vfio_pci_zdev_feat_aif(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_aif *data;
> + struct vfio_device_feature *feat;
> + unsigned long minsz;
> + int size, rc = 0;
> +
> + if (!zdev || !zdev->kzdev)
> + return -EINVAL;
> +
> + /*
> + * If PROBE requested and feature not found, leave immediately.
> + * Otherwise, keep going as GET or SET may also be specified.
> + */
> + if (feature.flags & VFIO_DEVICE_FEATURE_PROBE) {
> + rc = kvm_s390_pci_aif_probe(zdev);
> + if (rc)
> + return rc;
> + }
> + if (!(feature.flags & (VFIO_DEVICE_FEATURE_GET +
> + VFIO_DEVICE_FEATURE_SET)))
> + return 0;
> +
> + size = sizeof(*feat) + sizeof(*data);
> + feat = kzalloc(size, GFP_KERNEL);
> + if (!feat)
> + return -ENOMEM;
> +
> + data = (struct vfio_device_zpci_aif *)&feat->data;
> + minsz = offsetofend(struct vfio_device_feature, flags);

I think you should check the argsz.

> +
> + /* 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->kzdev->aif)
> + data->flags = VFIO_DEVICE_ZPCI_FLAG_AIF_FLOAT;
> + if (zdev->kzdev->fhost)
> + data->flags |= VFIO_DEVICE_ZPCI_FLAG_AIF_HOST;
> +
> + 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_AIF_FLOAT) {
> + /* create a guest fib */
> + struct zpci_fib fib;
> +
> + fib.fmt0.aibv = data->ibv;
> + fib.fmt0.isc = data->isc;
> + fib.fmt0.noi = data->noi;
> + if (data->sb != 0) {
> + fib.fmt0.aisb = data->sb;
> + fib.fmt0.aisbo = data->sbo;
> + fib.fmt0.sum = 1;
> + } else {
> + fib.fmt0.aisb = 0;
> + fib.fmt0.aisbo = 0;
> + fib.fmt0.sum = 0;
> + }
> + if (data->flags & VFIO_DEVICE_ZPCI_FLAG_AIF_HOST) {
> + rc = kvm_s390_pci_aif_enable(zdev, &fib, false);
> + if (!rc) {
> + zdev->kzdev->aif = true;
> + zdev->kzdev->fhost = true;
> + }
> + } else {
> + rc = kvm_s390_pci_aif_enable(zdev, &fib, true);
> + if (!rc)
> + zdev->kzdev->aif = true;
> + }
> + } else if (data->flags == 0) {
> + rc = kvm_s390_pci_aif_disable(zdev);
> + if (!rc) {
> + zdev->kzdev->aif = false;
> + zdev->kzdev->fhost = false;
> + }
> + } else {
> + rc = -EINVAL;
> + }
> + }
> +
> + kfree(feat);
> + return rc;
> +}
> +
> static int vfio_pci_zdev_group_notifier(struct notifier_block *nb,
> unsigned long action, void *data)
> {
> @@ -259,8 +351,10 @@ int vfio_pci_zdev_release(struct vfio_pci_core_device *vdev)
> * If the device was using interpretation, don't trust that userspace
> * did the appropriate cleanup
> */
> - if (zdev->gd != 0)
> + if (zdev->gd != 0) {
> + kvm_s390_pci_aif_disable(zdev);
> 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 92dc43c827c9..5442d3fa1662 100644
> --- a/include/linux/vfio_pci_core.h
> +++ b/include/linux/vfio_pci_core.h
> @@ -201,6 +201,9 @@ extern int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev,
> int vfio_pci_zdev_feat_interp(struct vfio_pci_core_device *vdev,
> struct vfio_device_feature feature,
> unsigned long arg);
> +int vfio_pci_zdev_feat_aif(struct vfio_pci_core_device *vdev,
> + struct vfio_device_feature feature,
> + unsigned long arg);
> int vfio_pci_zdev_open(struct vfio_pci_core_device *vdev);
> int vfio_pci_zdev_release(struct vfio_pci_core_device *vdev);
> #else
> @@ -217,6 +220,13 @@ static inline int vfio_pci_zdev_feat_interp(struct vfio_pci_core_device *vdev,
> return -ENOTTY;
> }
>
> +static inline int vfio_pci_zdev_feat_aif(struct vfio_pci_core_device *vdev,
> + struct vfio_device_feature feature,
> + unsigned long arg)
> +{
> + return -ENOTTY;
> +}
> +
> static inline int vfio_pci_zdev_open(struct vfio_pci_core_device *vdev)
> {
> return -ENODEV;
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index b9a75485b8e7..fe3bfd99bf50 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -1009,6 +1009,13 @@ struct vfio_device_feature {
> */
> #define VFIO_DEVICE_FEATURE_ZPCI_INTERP (1)
>
> +/*
> + * Provide support for enbaling adapter interruption forwarding 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_AIF (2)
> +
> /* -------- API for Type1 VFIO IOMMU -------- */
>
> /**
> diff --git a/include/uapi/linux/vfio_zdev.h b/include/uapi/linux/vfio_zdev.h
> index 575f0410dc66..c574e23f9385 100644
> --- a/include/uapi/linux/vfio_zdev.h
> +++ b/include/uapi/linux/vfio_zdev.h
> @@ -90,4 +90,24 @@ struct vfio_device_zpci_interp {
> __u32 fh; /* Host device function handle */
> };
>
> +/**
> + * VFIO_DEVICE_FEATURE_ZPCI_AIF
> + *
> + * This feature is used for enabling forwarding of adapter interrupts directly
> + * from firmware to the guest. When setting this feature, the flags indicate
> + * whether to enable/disable the feature and the structure defined below is
> + * used to setup the forwarding structures. When getting this feature, only
> + * the flags are used to indicate the current state.
> + */
> +struct vfio_device_zpci_aif {
> + __u64 flags;
> +#define VFIO_DEVICE_ZPCI_FLAG_AIF_FLOAT 1
> +#define VFIO_DEVICE_ZPCI_FLAG_AIF_HOST 2
> + __u64 ibv; /* Address of guest interrupt bit vector */
> + __u64 sb; /* Address of guest summary bit */
> + __u32 noi; /* Number of interrupts */
> + __u8 isc; /* Guest interrupt subclass */
> + __u8 sbo; /* Offset of guest summary bit vector */
> +};
> +
> #endif
>

--
Pierre Morel
IBM Lab Boeblingen