Re: [PATCH v5 4/9] s390x/pci: add routine to get host function handle from CLP info

[Pierre Morel <pmorel@linux.ibm.com>]

On 4/4/22 20:17, Matthew Rosato wrote:
> In order to interface with the underlying host zPCI device, we need
> to know it's function handle.  Add a routine to grab this from the
> vfio CLP capabilities chain.
> 
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>

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


> ---
>   hw/s390x/s390-pci-vfio.c         | 83 ++++++++++++++++++++++++++------
>   include/hw/s390x/s390-pci-vfio.h |  6 +++
>   2 files changed, 73 insertions(+), 16 deletions(-)
> 
> diff --git a/hw/s390x/s390-pci-vfio.c b/hw/s390x/s390-pci-vfio.c
> index 6f80a47e29..4bf0a7e22d 100644
> --- a/hw/s390x/s390-pci-vfio.c
> +++ b/hw/s390x/s390-pci-vfio.c
> @@ -124,6 +124,27 @@ static void s390_pci_read_base(S390PCIBusDevice *pbdev,
>       pbdev->zpci_fn.pft = 0;
>   }
>   
> +static bool get_host_fh(S390PCIBusDevice *pbdev, struct vfio_device_info *info,
> +                        uint32_t *fh)
> +{
> +    struct vfio_info_cap_header *hdr;
> +    struct vfio_device_info_cap_zpci_base *cap;
> +    VFIOPCIDevice *vpci =  container_of(pbdev->pdev, VFIOPCIDevice, pdev);
> +
> +    hdr = vfio_get_device_info_cap(info, VFIO_DEVICE_INFO_CAP_ZPCI_BASE);
> +
> +    /* Can only get the host fh with version 2 or greater */
> +    if (hdr == NULL || hdr->version < 2) {
> +        trace_s390_pci_clp_cap(vpci->vbasedev.name,
> +                               VFIO_DEVICE_INFO_CAP_ZPCI_BASE);
> +        return false;
> +    }
> +    cap = (void *) hdr;
> +
> +    *fh = cap->fh;
> +    return true;
> +}
> +
>   static void s390_pci_read_group(S390PCIBusDevice *pbdev,
>                                   struct vfio_device_info *info)
>   {
> @@ -217,25 +238,13 @@ static void s390_pci_read_pfip(S390PCIBusDevice *pbdev,
>       memcpy(pbdev->zpci_fn.pfip, cap->pfip, CLP_PFIP_NR_SEGMENTS);
>   }
>   
> -/*
> - * This function will issue the VFIO_DEVICE_GET_INFO ioctl and look for
> - * capabilities that contain information about CLP features provided by the
> - * underlying host.
> - * On entry, defaults have already been placed into the guest CLP response
> - * buffers.  On exit, defaults will have been overwritten for any CLP features
> - * found in the capability chain; defaults will remain for any CLP features not
> - * found in the chain.
> - */
> -void s390_pci_get_clp_info(S390PCIBusDevice *pbdev)
> +static struct vfio_device_info *get_device_info(S390PCIBusDevice *pbdev,
> +                                                uint32_t argsz)
>   {
> -    g_autofree struct vfio_device_info *info = NULL;
> +    struct vfio_device_info *info = g_malloc0(argsz);
>       VFIOPCIDevice *vfio_pci;
> -    uint32_t argsz;
>       int fd;
>   
> -    argsz = sizeof(*info);
> -    info = g_malloc0(argsz);
> -
>       vfio_pci = container_of(pbdev->pdev, VFIOPCIDevice, pdev);
>       fd = vfio_pci->vbasedev.fd;
>   
> @@ -250,7 +259,8 @@ retry:
>   
>       if (ioctl(fd, VFIO_DEVICE_GET_INFO, info)) {
>           trace_s390_pci_clp_dev_info(vfio_pci->vbasedev.name);
> -        return;
> +        free(info);
> +        return NULL;
>       }
>   
>       if (info->argsz > argsz) {
> @@ -259,6 +269,47 @@ retry:
>           goto retry;
>       }
>   
> +    return info;
> +}
> +
> +/*
> + * Get the host function handle from the vfio CLP capabilities chain.  Returns
> + * true if a fh value was placed into the provided buffer.  Returns false
> + * if a fh could not be obtained (ioctl failed or capabilitiy version does
> + * not include the fh)
> + */
> +bool s390_pci_get_host_fh(S390PCIBusDevice *pbdev, uint32_t *fh)
> +{
> +    g_autofree struct vfio_device_info *info = NULL;
> +
> +    assert(fh);
> +
> +    info = get_device_info(pbdev, sizeof(*info));
> +    if (!info) {
> +        return false;
> +    }
> +
> +    return get_host_fh(pbdev, info, fh);
> +}
> +
> +/*
> + * This function will issue the VFIO_DEVICE_GET_INFO ioctl and look for
> + * capabilities that contain information about CLP features provided by the
> + * underlying host.
> + * On entry, defaults have already been placed into the guest CLP response
> + * buffers.  On exit, defaults will have been overwritten for any CLP features
> + * found in the capability chain; defaults will remain for any CLP features not
> + * found in the chain.
> + */
> +void s390_pci_get_clp_info(S390PCIBusDevice *pbdev)
> +{
> +    g_autofree struct vfio_device_info *info = NULL;
> +
> +    info = get_device_info(pbdev, sizeof(*info));
> +    if (!info) {
> +        return;
> +    }
> +
>       /*
>        * Find the CLP features provided and fill in the guest CLP responses.
>        * Always call s390_pci_read_base first as information from this could
> diff --git a/include/hw/s390x/s390-pci-vfio.h b/include/hw/s390x/s390-pci-vfio.h
> index ff708aef50..0c2e4b5175 100644
> --- a/include/hw/s390x/s390-pci-vfio.h
> +++ b/include/hw/s390x/s390-pci-vfio.h
> @@ -20,6 +20,7 @@ bool s390_pci_update_dma_avail(int fd, unsigned int *avail);
>   S390PCIDMACount *s390_pci_start_dma_count(S390pciState *s,
>                                             S390PCIBusDevice *pbdev);
>   void s390_pci_end_dma_count(S390pciState *s, S390PCIDMACount *cnt);
> +bool s390_pci_get_host_fh(S390PCIBusDevice *pbdev, uint32_t *fh);
>   void s390_pci_get_clp_info(S390PCIBusDevice *pbdev);
>   #else
>   static inline bool s390_pci_update_dma_avail(int fd, unsigned int *avail)
> @@ -33,6 +34,11 @@ static inline S390PCIDMACount *s390_pci_start_dma_count(S390pciState *s,
>   }
>   static inline void s390_pci_end_dma_count(S390pciState *s,
>                                             S390PCIDMACount *cnt) { }
> +static inline bool s390_pci_get_host_fh(S390PCIBusDevice *pbdev,
> +                                        unsigned int *fh)
> +{
> +    return false;
> +}
>   static inline void s390_pci_get_clp_info(S390PCIBusDevice *pbdev) { }
>   #endif
>   
> 

-- 
Pierre Morel
IBM Lab Boeblingen