Re: [Xen-devel] [PATCH v2] vm_event: Add a new opcode to get VM_EVENT_INTERFACE_VERSION

[Tamas K Lengyel <tamas@xxxxxxxxxxxxx>]

On Thu, Feb 14, 2019 at 7:18 AM Petre Pircalabu
<ppircalabu@xxxxxxxxxxxxxxx> wrote:
>
> Currently, the VM_EVENT_INTERFACE_VERSION is determined at runtime, by
> inspecting the corresponding field in a vm_event_request. This helper
> opcode will query the hypervisor supported version before the vm_event
> related structures and layout are set-up.
>
> Signed-off-by: Petre Pircalabu <ppircalabu@xxxxxxxxxxxxxxx>

Acked-by: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>

>
> ---
> Changes from v1:
>  - Return -ESRCH instead of -EINVAL if DOMID_INVALID if given as
>    parameter to XEN_DOMCTL_vm_event_op and op is not
>    XEN_VM_EVENT_GET_VERSION. Also the log message was removed.
>  - Replace XEN_VM_EVENT_GET_INTERFACE_VERSION with
>    XEN_VM_EVENT_GET_VERSION.
>  - Replace the "get_interface_version" wrapper struct with a single
>    "version" field.
>  - Rename the libxc wrapper to xc_vm_event_get_version.
> ---
>  tools/libxc/include/xenctrl.h |  5 +++++
>  tools/libxc/xc_vm_event.c     | 18 +++++++++++++++++-
>  xen/common/domctl.c           |  1 +
>  xen/common/vm_event.c         | 11 ++++++++++-
>  xen/include/public/domctl.h   |  9 ++++++++-
>  5 files changed, 41 insertions(+), 3 deletions(-)
>
> diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
> index 31cdda7..a3628e5 100644
> --- a/tools/libxc/include/xenctrl.h
> +++ b/tools/libxc/include/xenctrl.h
> @@ -2003,6 +2003,11 @@ int xc_set_mem_access_multi(xc_interface *xch, 
> uint32_t domain_id,
>  int xc_get_mem_access(xc_interface *xch, uint32_t domain_id,
>                        uint64_t pfn, xenmem_access_t *access);
>
> +/*
> + * Returns the VM_EVENT_INTERFACE version.
> + */
> +int xc_vm_event_get_version(xc_interface *xch);
> +
>  /***
>   * Monitor control operations.
>   *
> diff --git a/tools/libxc/xc_vm_event.c b/tools/libxc/xc_vm_event.c
> index 8674607..a97c615 100644
> --- a/tools/libxc/xc_vm_event.c
> +++ b/tools/libxc/xc_vm_event.c
> @@ -35,7 +35,7 @@ int xc_vm_event_control(xc_interface *xch, uint32_t 
> domain_id, unsigned int op,
>
>      rc = do_domctl(xch, &domctl);
>      if ( !rc && port )
> -        *port = domctl.u.vm_event_op.port;
> +        *port = domctl.u.vm_event_op.u.enable.port;
>      return rc;
>  }
>
> @@ -156,6 +156,22 @@ void *xc_vm_event_enable(xc_interface *xch, uint32_t 
> domain_id, int param,
>      return ring_page;
>  }
>
> +int xc_vm_event_get_version(xc_interface *xch)
> +{
> +    DECLARE_DOMCTL;
> +    int rc;
> +
> +    domctl.cmd = XEN_DOMCTL_vm_event_op;
> +    domctl.domain = DOMID_INVALID;
> +    domctl.u.vm_event_op.op = XEN_VM_EVENT_GET_VERSION;
> +    domctl.u.vm_event_op.mode = XEN_DOMCTL_VM_EVENT_OP_MONITOR;
> +
> +    rc = do_domctl(xch, &domctl);
> +    if ( !rc )
> +        rc = domctl.u.vm_event_op.u.version;
> +    return rc;
> +}
> +
>  /*
>   * Local variables:
>   * mode: C
> diff --git a/xen/common/domctl.c b/xen/common/domctl.c
> index d08b627..bade9a6 100644
> --- a/xen/common/domctl.c
> +++ b/xen/common/domctl.c
> @@ -392,6 +392,7 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) 
> u_domctl)
>      switch ( op->cmd )
>      {
>      case XEN_DOMCTL_test_assign_device:
> +    case XEN_DOMCTL_vm_event_op:
>          if ( op->domain == DOMID_INVALID )
>          {
>      case XEN_DOMCTL_createdomain:
> diff --git a/xen/common/vm_event.c b/xen/common/vm_event.c
> index 26cfa2c..19c983c 100644
> --- a/xen/common/vm_event.c
> +++ b/xen/common/vm_event.c
> @@ -88,7 +88,7 @@ static int vm_event_enable(
>      if ( rc < 0 )
>          goto err;
>
> -    (*ved)->xen_port = vec->port = rc;
> +    (*ved)->xen_port = vec->u.enable.port = rc;
>
>      /* Prepare ring buffer */
>      FRONT_RING_INIT(&(*ved)->front_ring,
> @@ -592,6 +592,15 @@ int vm_event_domctl(struct domain *d, struct 
> xen_domctl_vm_event_op *vec,
>  {
>      int rc;
>
> +    if ( vec->op == XEN_VM_EVENT_GET_VERSION )
> +    {
> +        vec->u.version = VM_EVENT_INTERFACE_VERSION;
> +        return 0;
> +    }
> +
> +    if ( unlikely(d == NULL) )
> +        return -ESRCH;
> +
>      rc = xsm_vm_event_control(XSM_PRIV, d, vec->mode, vec->op);
>      if ( rc )
>          return rc;
> diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
> index 7e1cf21..19486d5 100644
> --- a/xen/include/public/domctl.h
> +++ b/xen/include/public/domctl.h
> @@ -781,6 +781,7 @@ struct xen_domctl_gdbsx_domstatus {
>  #define XEN_VM_EVENT_ENABLE               0
>  #define XEN_VM_EVENT_DISABLE              1
>  #define XEN_VM_EVENT_RESUME               2
> +#define XEN_VM_EVENT_GET_VERSION          3
>
>  /*
>   * Domain memory paging
> @@ -843,7 +844,13 @@ struct xen_domctl_vm_event_op {
>      uint32_t       op;           /* XEN_VM_EVENT_* */
>      uint32_t       mode;         /* XEN_DOMCTL_VM_EVENT_OP_* */
>
> -    uint32_t port;              /* OUT: event channel for ring */
> +    union {
> +        struct {
> +            uint32_t port;       /* OUT: event channel for ring */
> +        } enable;
> +
> +        uint32_t version;
> +    } u;
>  };
>
>  /*
> --
> 2.7.4

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