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Message-ID: <75c74f80-0a74-40dc-6797-473522ef2803@linux.ibm.com>
Date: Tue, 25 Jan 2022 13:36:19 +0100
From: Pierre Morel <pmorel@...ux.ibm.com>
To: Matthew Rosato <mjrosato@...ux.ibm.com>, linux-s390@...r.kernel.org
Cc: alex.williamson@...hat.com, cohuck@...hat.com,
schnelle@...ux.ibm.com, farman@...ux.ibm.com,
borntraeger@...ux.ibm.com, hca@...ux.ibm.com, gor@...ux.ibm.com,
gerald.schaefer@...ux.ibm.com, agordeev@...ux.ibm.com,
frankja@...ux.ibm.com, david@...hat.com, imbrenda@...ux.ibm.com,
vneethv@...ux.ibm.com, oberpar@...ux.ibm.com, freude@...ux.ibm.com,
thuth@...hat.com, pasic@...ux.ibm.com, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 26/30] vfio-pci/zdev: wire up zPCI adapter interrupt
forwarding support
On 1/14/22 21:31, 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@...ux.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 | 98 +++++++++++++++++++++++++++++++-
> include/linux/vfio_pci_core.h | 10 ++++
> include/uapi/linux/vfio.h | 7 +++
> include/uapi/linux/vfio_zdev.h | 20 +++++++
> 6 files changed, 138 insertions(+), 1 deletion(-)
>
> diff --git a/arch/s390/include/asm/kvm_pci.h b/arch/s390/include/asm/kvm_pci.h
> index dc00c3f27a00..dbab349a4a75 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;
Can we please have a comment on these booleans?
Can we have explicit naming to be able to follow their usage more easily?
May be aif_float and aif_host to match with the VFIO feature?
> };
>
> 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 4339f48b98bc..891cfa016d63 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>
> @@ -208,6 +209,99 @@ 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 specified, return probe results immediately */
> + if (feature.flags & VFIO_DEVICE_FEATURE_PROBE)
> + return kvm_s390_pci_aif_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_aif *)&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->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;
> + }
> + } 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)
> {
> @@ -255,8 +349,10 @@ void 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 0db2b1051931..7ec5e82e7933 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);
> void vfio_pci_zdev_open(struct vfio_pci_core_device *vdev);
> void 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 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 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
I think we need more information on these flags.
What does AIF_FLOAT and what does AIF_HOST ?
> + __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
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