Re: [Xen-devel] [PATCH 4/5] libxc/arm: allocate xenstore and console pages

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2012-06-22 at 17:09 +0100, Stefano Stabellini wrote:
> Allocate two additional pages at the end of the guest physical memory
> for xenstore and console.
> Set HVM_PARAM_STORE_PFN and HVM_PARAM_CONSOLE_PFN to the corresponding
> values.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> ---
>  tools/libxc/xc_dom_arm.c |   32 ++++++++++++++++++++++----------
>  1 files changed, 22 insertions(+), 10 deletions(-)
> 
> diff --git a/tools/libxc/xc_dom_arm.c b/tools/libxc/xc_dom_arm.c
> index bb86139..df2eefe 100644
> --- a/tools/libxc/xc_dom_arm.c
> +++ b/tools/libxc/xc_dom_arm.c
> @@ -25,6 +25,10 @@
>  #include "xg_private.h"
>  #include "xc_dom.h"
>  
> +#define NR_MAGIC_PAGES 2
> +#define CONSOLE_PFN_OFFSET 0
> +#define XENSTORE_PFN_OFFSET 1
> +
>  /* ------------------------------------------------------------------------ 
> */
>  /*
>   * arm guests are hybrid and start off with paging disabled, therefore no
> @@ -47,12 +51,6 @@ static int setup_pgtables_arm(struct xc_dom_image *dom)
>  static int alloc_magic_pages(struct xc_dom_image *dom)
>  {
>      DOMPRINTF_CALLED(dom->xch);
> -    /* XXX
> -     *   dom->p2m_guest
> -     *   dom->start_info_pfn
> -     *   dom->xenstore_pfn
> -     *   dom->console_pfn
> -     */
>      return 0;
>  }
>  
> @@ -127,18 +125,19 @@ int arch_setup_meminit(struct xc_dom_image *dom)
>  {
>      int rc;
>      xen_pfn_t pfn, allocsz, i;
> +    xen_pfn_t store_pfn, console_pfn;
>  
>      fprintf(stderr, "%s: tot pages %"PRI_xen_pfn" rambase %"PRI_xen_pfn"\n", 
> __func__,
>              dom->total_pages, dom->rambase_pfn);
>  
>      dom->shadow_enabled = 1;
>  
> -    dom->p2m_host = xc_dom_malloc(dom, sizeof(xen_pfn_t) * dom->total_pages);
> +    dom->p2m_host = xc_dom_malloc(dom, sizeof(xen_pfn_t) * (dom->total_pages 
> + NR_MAGIC_PAGES));
>  
>      fprintf(stderr, "%s: setup p2m from %"PRI_xen_pfn" for %"PRI_xen_pfn" 
> pages\n", __func__,
>              dom->rambase_pfn, dom->total_pages );
>      /* setup initial p2m */
> -    for ( pfn = 0; pfn < dom->total_pages; pfn++ )
> +    for ( pfn = 0; pfn < (dom->total_pages + NR_MAGIC_PAGES); pfn++ )
>          dom->p2m_host[pfn] = pfn + dom->rambase_pfn;
>  
>      fprintf(stderr, "%s: init'd p2m_host[0] = %"PRI_xen_pfn"\n", __func__, 
> dom->p2m_host[0]);
> @@ -148,10 +147,10 @@ int arch_setup_meminit(struct xc_dom_image *dom)
>  
>      /* allocate guest memory */
>      for ( i = rc = allocsz = 0;
> -          (i < dom->total_pages) && !rc;
> +          (i < dom->total_pages + NR_MAGIC_PAGES) && !rc;
>            i += allocsz )
>      {
> -        allocsz = dom->total_pages - i;
> +        allocsz = (dom->total_pages + NR_MAGIC_PAGES) - i;

All these "+ NR_MAGIC_PAGES" are a bit troublesome looking.

Do these pages need to be in p2m_host or would it be fine to just insert
them into the guest p2m individually outside the main allocation logic?

Otherwise perhaps simply int total_pages = dom->total_pages + NR... and
use throughout?

>          if ( allocsz > 1024*1024 )
>              allocsz = 1024*1024;
>          fprintf(stderr, "alloc %"PRI_xen_pfn" at offset %"PRI_xen_pfn" which 
> is %"PRI_xen_pfn"\n",
> @@ -168,6 +167,19 @@ int arch_setup_meminit(struct xc_dom_image *dom)
>      fprintf(stderr, "%s: popl'd p2m_host[%"PRI_xen_pfn"] = %"PRI_xen_pfn"\n",
>              __func__, dom->total_pages-1, dom->p2m_host[dom->total_pages-1]);

I really need to scrub the debug printfs from my patch...

>  
> +    console_pfn = dom->rambase_pfn + dom->total_pages + CONSOLE_PFN_OFFSET;
> +    store_pfn = dom->rambase_pfn + dom->total_pages + XENSTORE_PFN_OFFSET;
> +
> +    xc_clear_domain_page(dom->xch, dom->guest_domid, console_pfn);
> +    xc_clear_domain_page(dom->xch, dom->guest_domid, store_pfn);
> +    xc_set_hvm_param(dom->xch, dom->guest_domid, HVM_PARAM_CONSOLE_PFN,
> +            console_pfn);
> +    xc_set_hvm_param(dom->xch, dom->guest_domid, HVM_PARAM_STORE_PFN,
> +            store_pfn);
> +
> +    fprintf(stderr, "%s: console_pfn=%"PRI_xen_pfn" 
> xenstore_pfn=%"PRI_xen_pfn"\n",
> +            __func__, console_pfn, store_pfn);

... and so do you ;-)



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