Re: [PATCH 07/12] s390x/pci: enable for load/store intepretation

[Thomas Huth <thuth@redhat.com>]

On 07/12/2021 22.04, Matthew Rosato wrote:
> Use the associated vfio feature ioctl to enable interpretation for devices
> when requested.  As part of this process, we must use the host function
> handle rather than a QEMU-generated one -- this is provided as part of the
> ioctl payload.
> 
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> ---
>   hw/s390x/s390-pci-bus.c          | 69 +++++++++++++++++++++++++++++++-
>   hw/s390x/s390-pci-inst.c         | 63 ++++++++++++++++++++++++++++-
>   hw/s390x/s390-pci-vfio.c         | 55 +++++++++++++++++++++++++
>   include/hw/s390x/s390-pci-bus.h  |  1 +
>   include/hw/s390x/s390-pci-vfio.h | 15 +++++++
>   5 files changed, 201 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
> index 01b58ebc70..451bd32d92 100644
> --- a/hw/s390x/s390-pci-bus.c
> +++ b/hw/s390x/s390-pci-bus.c
> @@ -971,12 +971,57 @@ static void s390_pci_update_subordinate(PCIDevice *dev, uint32_t nr)
>       }
>   }
>   
> +static int s390_pci_interp_plug(S390pciState *s, S390PCIBusDevice *pbdev)
> +{
> +    uint32_t idx;
> +    int rc;
> +
> +    rc = s390_pci_probe_interp(pbdev);
> +    if (rc) {
> +        return rc;
> +    }
> +
> +    rc = s390_pci_update_passthrough_fh(pbdev);
> +    if (rc) {
> +        return rc;
> +    }
> +
> +    /*
> +     * The host device is in an enabled state, but the device must
> +     * begin as disabled for the guest so mask off the enable bit
> +     * from the passthrough handle.
> +     */
> +    pbdev->fh &= ~FH_MASK_ENABLE;
> +
> +    /* Next, see if the idx is already in-use */
> +    idx = pbdev->fh & FH_MASK_INDEX;
> +    if (pbdev->idx != idx) {
> +        if (s390_pci_find_dev_by_idx(s, idx)) {
> +            return -EINVAL;
> +        }
> +        /*
> +         * Update the idx entry with the passed through idx
> +         * If the relinquised idx is lower than next_idx, use it

s/relinquised/relinquished/

> +         * to replace next_idx
> +         */
> +        g_hash_table_remove(s->zpci_table, &pbdev->idx);
> +        if (idx < s->next_idx) {
> +            s->next_idx = idx;
> +        }
> +        pbdev->idx = idx;
> +        g_hash_table_insert(s->zpci_table, &pbdev->idx, pbdev);
> +    }
> +
> +    return 0;
> +}
[...]
> diff --git a/hw/s390x/s390-pci-vfio.c b/hw/s390x/s390-pci-vfio.c
> index 6f80a47e29..78093aaac7 100644
> --- a/hw/s390x/s390-pci-vfio.c
> +++ b/hw/s390x/s390-pci-vfio.c
> @@ -97,6 +97,61 @@ void s390_pci_end_dma_count(S390pciState *s, S390PCIDMACount *cnt)
>       }
>   }
>   
> +int s390_pci_probe_interp(S390PCIBusDevice *pbdev)
> +{
> +    VFIOPCIDevice *vdev = container_of(pbdev->pdev, VFIOPCIDevice, pdev);
> +    struct vfio_device_feature feat = {
> +        .argsz = sizeof(struct vfio_device_feature),
> +        .flags = VFIO_DEVICE_FEATURE_PROBE + VFIO_DEVICE_FEATURE_ZPCI_INTERP
> +    };
> +
> +    return ioctl(vdev->vbasedev.fd, VFIO_DEVICE_FEATURE, &feat);
> +}
> +
> +int s390_pci_set_interp(S390PCIBusDevice *pbdev, bool enable)
> +{
> +    VFIOPCIDevice *vdev = container_of(pbdev->pdev, VFIOPCIDevice, pdev);
> +    g_autofree struct vfio_device_feature *feat;

IIRC there have been compiler versions that complain if a g_autofree 
variable is initialized at the point of declaration, so you might need to 
add the "= g_malloc0(size)" here already.

> +    struct vfio_device_zpci_interp *data;
> +    int size;
> +
> +    size = sizeof(*feat) + sizeof(*data);
> +    feat = g_malloc0(size);
> +    feat->argsz = size;
> +    feat->flags = VFIO_DEVICE_FEATURE_SET + VFIO_DEVICE_FEATURE_ZPCI_INTERP;
> +
> +    data = (struct vfio_device_zpci_interp *)&feat->data;
> +    if (enable) {
> +        data->flags = VFIO_DEVICE_ZPCI_FLAG_INTERP;
> +    } else {
> +        data->flags = 0;
> +    }
> +
> +    return ioctl(vdev->vbasedev.fd, VFIO_DEVICE_FEATURE, feat);
> +}
> +
> +int s390_pci_update_passthrough_fh(S390PCIBusDevice *pbdev)
> +{
> +    VFIOPCIDevice *vdev = container_of(pbdev->pdev, VFIOPCIDevice, pdev);
> +    g_autofree struct vfio_device_feature *feat;

dito

> +    struct vfio_device_zpci_interp *data;
> +    int size, rc;
> +
> +    size = sizeof(*feat) + sizeof(*data);
> +    feat = g_malloc0(size);
> +    feat->argsz = size;
> +    feat->flags = VFIO_DEVICE_FEATURE_GET + VFIO_DEVICE_FEATURE_ZPCI_INTERP;
> +
> +    rc = ioctl(vdev->vbasedev.fd, VFIO_DEVICE_FEATURE, feat);
> +    if (rc) {
> +        return rc;
> +    }
> +
> +    data = (struct vfio_device_zpci_interp *)&feat->data;
> +    pbdev->fh = data->fh;
> +    return 0;
> +}

  Thomas