Re: [PATCH v3 4/7] sysctl: Add sysctl interface for querying PCI topology

[Andrew Cooper <andrew.cooper3%citrix.com@localhost>]

On 09/02/15 20:04, Boris Ostrovsky wrote:
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky%oracle.com@localhost>
> ---
>  xen/common/sysctl.c         |   73 +++++++++++++++++++++++++++++++++++++++++++
>  xen/include/public/sysctl.h |   29 +++++++++++++++++
>  2 files changed, 102 insertions(+), 0 deletions(-)
>
> diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c
> index 30c5806..ea6557f 100644
> --- a/xen/common/sysctl.c
> +++ b/xen/common/sysctl.c
> @@ -384,7 +384,80 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) u_sysctl)
>          xfree(cputopo);
>      }
>      break;
> +#ifdef HAS_PCI
> +    case XEN_SYSCTL_pcitopoinfo:
> +    {
> +        xen_sysctl_pcitopoinfo_t *ti = &op->u.pcitopoinfo;
> +        physdev_pci_device_t *devs;
> +        uint8_t *nodes;
> +        unsigned int first_dev, i;
> +        int num_devs;
> +
> +        num_devs = ti->num_devs - ti->first_dev;
> +
> +        if ( guest_handle_is_null(ti->devs) ||
> +             guest_handle_is_null(ti->nodes) ||
> +             (num_devs <= 0) )
> +        {
> +            ret = -EINVAL;
> +            break;
> +        }
> +
> +        devs = xmalloc_array(physdev_pci_device_t, num_devs);
> +        nodes = xmalloc_array(uint8_t, num_devs);

You can do all of this without any memory allocation at all, which will
simplify your error handling substantially.

Something along the lines of

for(...)
{
    copy one physdev_pci_device_t from the guest

    do the lookup

    copy one node id back to the guest
}

~Andrew

> +        if ( !devs || !nodes )
> +        {
> +            xfree(devs);
> +            xfree(nodes);
> +            ret = -ENOMEM;
> +            break;
> +        }
> +
> +        first_dev = ti->first_dev;
> +
> +        if ( copy_from_guest_offset(devs, ti->devs, first_dev, num_devs) )
> +        {
> +            xfree(devs);
> +            xfree(nodes);
> +            ret = -EFAULT;
> +            break;
> +        }
>  
> +        for ( i = 0; i < num_devs; i++ )
> +        {
> +            struct pci_dev *pdev;
> +
> +            spin_lock(&pcidevs_lock);
> +            pdev = pci_get_pdev(devs[i].seg, devs[i].bus, devs[i].devfn);
> +            if ( !pdev || (pdev->node == NUMA_NO_NODE) )
> +                nodes[i] = INVALID_NODE_ID;
> +            else
> +                nodes[i] = pdev->node;
> +            spin_unlock(&pcidevs_lock);
> +
> +            if ( hypercall_preempt_check() )
> +                break;
> +        }
> +
> +        ti->first_dev += i + 1;
> +
> +        if ( __copy_field_to_guest(u_sysctl, op,
> +                                   u.pcitopoinfo.first_dev) ||
> +             copy_to_guest_offset(ti->nodes, first_dev, nodes,num_devs) )
> +        {
> +            ret = -EFAULT;
> +            break;
> +        }
> +
> +        if ( ti->first_dev < ti->num_devs )
> +            ret = hypercall_create_continuation(__HYPERVISOR_sysctl,
> +                                               "h", u_sysctl);
> +
> +        xfree(devs);
> +        xfree(nodes);
> +    }
> +    break;
> +#endif
>  #ifdef TEST_COVERAGE
>      case XEN_SYSCTL_coverage_op:
>          ret = sysctl_coverage_op(&op->u.coverage_op);
> diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
> index 7c78f81..044c3a1 100644
> --- a/xen/include/public/sysctl.h
> +++ b/xen/include/public/sysctl.h
> @@ -33,6 +33,7 @@
>  
>  #include "xen.h"
>  #include "domctl.h"
> +#include "physdev.h"
>  
>  #define XEN_SYSCTL_INTERFACE_VERSION 0x0000000C
>  
> @@ -494,6 +495,32 @@ struct xen_sysctl_cputopoinfo {
>  typedef struct xen_sysctl_cputopoinfo xen_sysctl_cputopoinfo_t;
>  DEFINE_XEN_GUEST_HANDLE(xen_sysctl_cputopoinfo_t);
>  
> +/* XEN_SYSCTL_pcitopoinfo */
> +struct xen_sysctl_pcitopoinfo {
> +    /* IN: Size of pcitopo array */
> +    uint32_t num_devs;
> +
> +    /*
> +     * IN/OUT: First element of pcitopo array that needs to be processed by
> +     * hypervisor.
> +     * This is used primarily by hypercall continuations and callers will
> +     * typically set it to zero
> +     */
> +    uint32_t first_dev;
> +
> +    /* IN: list of devices */
> +    XEN_GUEST_HANDLE_64(physdev_pci_device_t) devs;
> +
> +    /*
> +     * OUT: node identifier for each device.
> +     * If information for a particular device is not avalable then set
> +     * to INVALID_NODE_ID.
> +     */
> +    XEN_GUEST_HANDLE_64(uint8) nodes;
> +};
> +typedef struct xen_sysctl_pcitopoinfo xen_sysctl_pcitopoinfo_t;
> +DEFINE_XEN_GUEST_HANDLE(xen_sysctl_pcitopoinfo_t);
> +
>  /* XEN_SYSCTL_numainfo */
>  #define INVALID_MEM_SZ (~0U)
>  
> @@ -692,12 +719,14 @@ struct xen_sysctl {
>  #define XEN_SYSCTL_scheduler_op                  19
>  #define XEN_SYSCTL_coverage_op                   20
>  #define XEN_SYSCTL_psr_cmt_op                    21
> +#define XEN_SYSCTL_pcitopoinfo                   22
>      uint32_t interface_version; /* XEN_SYSCTL_INTERFACE_VERSION */
>      union {
>          struct xen_sysctl_readconsole       readconsole;
>          struct xen_sysctl_tbuf_op           tbuf_op;
>          struct xen_sysctl_physinfo          physinfo;
>          struct xen_sysctl_cputopoinfo       cputopoinfo;
> +        struct xen_sysctl_pcitopoinfo       pcitopoinfo;
>          struct xen_sysctl_numainfo          numainfo;
>          struct xen_sysctl_sched_id          sched_id;
>          struct xen_sysctl_perfc_op          perfc_op;