Re: [Xen-devel] [PATCH v2 3/5] xenfb: Add option to use a grant ref for shared page

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 17 Sep 2014, Owen smith wrote:
> Adds "page-gref" to the frontend location to specify the grant
> reference of the shared page. Adds the DEVOPS_FLAG_NEED_GNTDEV to
> both vfb and vkbd device flags. "page-ref" is checked first to
> avoid breaking existing frontends.
> 
> "page-gref"
>     Value: <uint32_t>
>     Grant reference to use to map the shared ring. Only used if
>     "page-ref" is not set.
> 
> Signed-off-by: Owen smith <owen.smith@xxxxxxxxxx>

As Ian pointed out, the docs need to be updated before I am going to
push this change upstream.
Aside from that

Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>


>  hw/display/xenfb.c | 44 ++++++++++++++++++++++++++++++++++----------
>  1 file changed, 34 insertions(+), 10 deletions(-)
> 
> diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
> index 69471e9..829036f 100644
> --- a/hw/display/xenfb.c
> +++ b/hw/display/xenfb.c
> @@ -54,6 +54,7 @@
>  struct common {
>      struct XenDevice  xendev;  /* must be first */
>      void              *page;
> +    int               page_gref;
>      QemuConsole       *con;
>  };
>  
> @@ -96,22 +97,38 @@ static int common_bind(struct common *c)
>  {
>      uint64_t mfn;
>  
> -    if (xenstore_read_fe_uint64(&c->xendev, "page-ref", &mfn) == -1)
> -     return -1;
> -    assert(mfn == (xen_pfn_t)mfn);
> +    if (xenstore_read_fe_uint64(&c->xendev, "page-ref", &mfn) == -1) {
> +        if (xenstore_read_fe_int(&c->xendev, "page-gref", &c->page_gref) == 
> -1) {
> +            return -1;
> +        }
> +    }
>  
>      if (xenstore_read_fe_int(&c->xendev, "event-channel", 
> &c->xendev.remote_port) == -1)
>       return -1;
>  
> -    c->page = xc_map_foreign_range(xen_xc, c->xendev.dom,
> -                                XC_PAGE_SIZE,
> -                                PROT_READ | PROT_WRITE, mfn);
> +    if (c->page_gref) {
> +        c->page = xc_gnttab_map_grant_ref(c->xendev.gnttabdev,
> +                                          c->xendev.dom, c->page_gref,
> +                                          PROT_READ | PROT_WRITE);
> +    } else {
> +        assert(mfn == (xen_pfn_t)mfn);
> +        c->page = xc_map_foreign_range(xen_xc, c->xendev.dom,
> +                                       XC_PAGE_SIZE,
> +                                       PROT_READ | PROT_WRITE, mfn);
> +    }
>      if (c->page == NULL)
>       return -1;
>  
>      xen_be_bind_evtchn(&c->xendev);
> -    xen_be_printf(&c->xendev, 1, "ring mfn %"PRIx64", remote-port %d, 
> local-port %d\n",
> -               mfn, c->xendev.remote_port, c->xendev.local_port);
> +    if (c->page_gref) {
> +        xen_be_printf(&c->xendev, 1,
> +                      "ring gref %d, remote-port %d, local-port %d\n",
> +                      c->page_gref, c->xendev.remote_port, 
> c->xendev.local_port);
> +    } else {
> +        xen_be_printf(&c->xendev, 1,
> +                      "ring mfn %"PRIx64", remote-port %d, local-port %d\n",
> +                      mfn, c->xendev.remote_port, c->xendev.local_port);
> +    }
>  
>      return 0;
>  }
> @@ -120,8 +137,13 @@ static void common_unbind(struct common *c)
>  {
>      xen_be_unbind_evtchn(&c->xendev);
>      if (c->page) {
> -     munmap(c->page, XC_PAGE_SIZE);
> -     c->page = NULL;
> +        if (c->page_gref) {
> +            xc_gnttab_munmap(c->xendev.gnttabdev, c->page, 1);
> +        } else {
> +            munmap(c->page, XC_PAGE_SIZE);
> +        }
> +        c->page = NULL;
> +        c->page_gref = 0;
>      }
>  }
>  
> @@ -954,6 +976,7 @@ static void fb_event(struct XenDevice *xendev)
>  
>  struct XenDevOps xen_kbdmouse_ops = {
>      .size       = sizeof(struct XenInput),
> +    .flags      = DEVOPS_FLAG_NEED_GNTDEV,
>      .init       = input_init,
>      .initialise = input_initialise,
>      .connected  = input_connected,
> @@ -963,6 +986,7 @@ struct XenDevOps xen_kbdmouse_ops = {
>  
>  struct XenDevOps xen_framebuffer_ops = {
>      .size       = sizeof(struct XenFB),
> +    .flags      = DEVOPS_FLAG_NEED_GNTDEV,
>      .init       = fb_init,
>      .initialise = fb_initialise,
>      .disconnect = fb_disconnect,
> -- 
> 2.1.0
> 

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