Re: [Xen-devel] [PATCH v2 3/6] xen: factor out allocation of page tables into separate function

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Thu, Feb 11, 2016 at 08:53:23AM +0100, Juergen Gross wrote:
> Do the allocation of page tables in a separate function. This will
> allow to do the allocation at different times of the boot preparations
> depending on the features the kernel is supporting.
>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> ---
>  grub-core/loader/i386/xen.c | 82 
> ++++++++++++++++++++++++++++-----------------
>  1 file changed, 51 insertions(+), 31 deletions(-)
>
> diff --git a/grub-core/loader/i386/xen.c b/grub-core/loader/i386/xen.c
> index e48cc3f..65cec27 100644
> --- a/grub-core/loader/i386/xen.c
> +++ b/grub-core/loader/i386/xen.c
> @@ -56,6 +56,9 @@ static struct grub_relocator_xen_state state;
>  static grub_xen_mfn_t *virt_mfn_list;
>  static struct start_info *virt_start_info;
>  static grub_xen_mfn_t console_pfn;
> +static grub_uint64_t *virt_pgtable;
> +static grub_uint64_t pgtbl_start;
> +static grub_uint64_t pgtbl_end;

Same as in patches #1 and #2.

>  #define PAGE_SIZE 4096
>  #define MAX_MODULES (PAGE_SIZE / sizeof (struct xen_multiboot_mod_list))
> @@ -106,17 +109,17 @@ get_pgtable_size (grub_uint64_t total_pages, 
> grub_uint64_t virt_base)
>
>  static void
>  generate_page_table (grub_uint64_t *where, grub_uint64_t paging_start,
> -                  grub_uint64_t total_pages, grub_uint64_t virt_base,
> -                  grub_xen_mfn_t *mfn_list)
> +                  grub_uint64_t paging_end, grub_uint64_t total_pages,
> +                  grub_uint64_t virt_base, grub_xen_mfn_t *mfn_list)
>  {
>    if (!virt_base)
> -    total_pages++;
> +    paging_end++;
>
>    grub_uint64_t lx[NUMBER_OF_LEVELS], lxs[NUMBER_OF_LEVELS];
>    grub_uint64_t nlx, nls, sz = 0;
>    int l;
>
> -  nlx = total_pages;
> +  nlx = paging_end;
>    nls = virt_base >> PAGE_SHIFT;
>    for (l = 0; l < NUMBER_OF_LEVELS; l++)
>      {
> @@ -160,7 +163,7 @@ generate_page_table (grub_uint64_t *where, grub_uint64_t 
> paging_start,
>    if (pr)
>      pg += POINTERS_PER_PAGE;
>
> -  for (j = 0; j < total_pages; j++)
> +  for (j = 0; j < paging_end; j++)
>      {
>        if (j >= paging_start && j < lp)
>       pg[j + lxs[0]] = page2offset (mfn_list[j]) | 5;
> @@ -261,24 +264,12 @@ grub_xen_special_alloc (void)
>  }
>
>  static grub_err_t
> -grub_xen_boot (void)
> +grub_xen_pt_alloc (void)
>  {
>    grub_relocator_chunk_t ch;
>    grub_err_t err;
>    grub_uint64_t nr_info_pages;
>    grub_uint64_t nr_pages, nr_pt_pages, nr_need_pages;
> -  struct gnttab_set_version gnttab_setver;
> -  grub_size_t i;
> -
> -  if (grub_xen_n_allocated_shared_pages)
> -    return grub_error (GRUB_ERR_BUG, "active grants");
> -
> -  err = grub_xen_p2m_alloc ();
> -  if (err)
> -    return err;
> -  err = grub_xen_special_alloc ();
> -  if (err)
> -    return err;
>
>    next_start.pt_base = max_addr + xen_inf.virt_base;
>    state.paging_start = max_addr >> PAGE_SHIFT;
> @@ -298,30 +289,59 @@ grub_xen_boot (void)
>        nr_pages = nr_need_pages;
>      }
>
> -  grub_dprintf ("xen", "bootstrap domain %llx+%llx\n",
> -             (unsigned long long) xen_inf.virt_base,
> -             (unsigned long long) page2offset (nr_pages));
> -
>    err = grub_relocator_alloc_chunk_addr (relocator, &ch,
>                                        max_addr, page2offset (nr_pt_pages));
>    if (err)
>      return err;
>
> +  virt_pgtable = get_virtual_current_address (ch);
> +  pgtbl_start = max_addr >> PAGE_SHIFT;
> +  max_addr += page2offset (nr_pt_pages);
> +  state.stack = max_addr + STACK_SIZE + xen_inf.virt_base;
> +  state.paging_size = nr_pt_pages;
> +  next_start.nr_pt_frames = nr_pt_pages;
> +  max_addr = page2offset (nr_pages);
> +  pgtbl_end = nr_pages;
> +
> +  return GRUB_ERR_NONE;
> +}
> +
> +static grub_err_t
> +grub_xen_boot (void)
> +{
> +  grub_err_t err;
> +  grub_uint64_t nr_pages;
> +  struct gnttab_set_version gnttab_setver;
> +  grub_size_t i;
> +
> +  if (grub_xen_n_allocated_shared_pages)
> +    return grub_error (GRUB_ERR_BUG, "active grants");
> +
> +  err = grub_xen_p2m_alloc ();
> +  if (err)
> +    return err;
> +  err = grub_xen_special_alloc ();
> +  if (err)
> +    return err;
> +  err = grub_xen_pt_alloc ();
> +  if (err)
> +    return err;

Should not we free memory allocated by grub_xen_p2m_alloc() and
grub_xen_special_alloc() if grub_xen_pt_alloc() failed?

Daniel

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