diff mbox

[v3,08/10] xen: add capability to load initrd outside of initial mapping

Message ID 1455729577-23702-9-git-send-email-jgross@suse.com (mailing list archive)
State New, archived
Headers show

Commit Message

Jürgen Groß Feb. 17, 2016, 5:19 p.m. UTC
Modern pvops linux kernels support an initrd not covered by the initial
mapping. This capability is flagged by an elf-note.

In case the elf-note is set by the kernel don't place the initrd into
the initial mapping. This will allow to load larger initrds and/or
support domains with larger memory, as the initial mapping is limited
to 2GB and it is containing the p2m list.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 grub-core/loader/i386/xen.c        | 61 ++++++++++++++++++++++++++++++--------
 grub-core/loader/i386/xen_fileXX.c |  3 ++
 include/grub/xen_file.h            |  1 +
 3 files changed, 52 insertions(+), 13 deletions(-)

Comments

Daniel Kiper Feb. 18, 2016, 11:18 a.m. UTC | #1
On Wed, Feb 17, 2016 at 06:19:35PM +0100, Juergen Gross wrote:
> Modern pvops linux kernels support an initrd not covered by the initial
> mapping. This capability is flagged by an elf-note.
>
> In case the elf-note is set by the kernel don't place the initrd into
> the initial mapping. This will allow to load larger initrds and/or
> support domains with larger memory, as the initial mapping is limited
> to 2GB and it is containing the p2m list.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>

One nitpick.

Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

> ---
>  grub-core/loader/i386/xen.c        | 61 ++++++++++++++++++++++++++++++--------
>  grub-core/loader/i386/xen_fileXX.c |  3 ++
>  include/grub/xen_file.h            |  1 +
>  3 files changed, 52 insertions(+), 13 deletions(-)
>
> diff --git a/grub-core/loader/i386/xen.c b/grub-core/loader/i386/xen.c
> index 3bcf4c8..7ac74f6 100644
> --- a/grub-core/loader/i386/xen.c
> +++ b/grub-core/loader/i386/xen.c
> @@ -58,6 +58,7 @@ struct xen_loader_state {
>    grub_uint64_t modules_target_start;
>    grub_size_t n_modules;
>    int loaded;
> +  int alloc_end_called;
>  };
>
>  static struct xen_loader_state xen_state;
> @@ -320,6 +321,28 @@ grub_xen_pt_alloc (void)
>  }
>
>  static grub_err_t
> +grub_xen_alloc_end (void)

Why is it called grub_xen_alloc_end()?
Could we use just grub_xen_alloc()?

Daniel
Jürgen Groß Feb. 18, 2016, 12:43 p.m. UTC | #2
On 18/02/16 12:18, Daniel Kiper wrote:
> On Wed, Feb 17, 2016 at 06:19:35PM +0100, Juergen Gross wrote:
>> Modern pvops linux kernels support an initrd not covered by the initial
>> mapping. This capability is flagged by an elf-note.
>>
>> In case the elf-note is set by the kernel don't place the initrd into
>> the initial mapping. This will allow to load larger initrds and/or
>> support domains with larger memory, as the initial mapping is limited
>> to 2GB and it is containing the p2m list.
>>
>> Signed-off-by: Juergen Gross <jgross@suse.com>
> 
> One nitpick.
> 
> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
> 
>> ---
>>  grub-core/loader/i386/xen.c        | 61 ++++++++++++++++++++++++++++++--------
>>  grub-core/loader/i386/xen_fileXX.c |  3 ++
>>  include/grub/xen_file.h            |  1 +
>>  3 files changed, 52 insertions(+), 13 deletions(-)
>>
>> diff --git a/grub-core/loader/i386/xen.c b/grub-core/loader/i386/xen.c
>> index 3bcf4c8..7ac74f6 100644
>> --- a/grub-core/loader/i386/xen.c
>> +++ b/grub-core/loader/i386/xen.c
>> @@ -58,6 +58,7 @@ struct xen_loader_state {
>>    grub_uint64_t modules_target_start;
>>    grub_size_t n_modules;
>>    int loaded;
>> +  int alloc_end_called;
>>  };
>>
>>  static struct xen_loader_state xen_state;
>> @@ -320,6 +321,28 @@ grub_xen_pt_alloc (void)
>>  }
>>
>>  static grub_err_t
>> +grub_xen_alloc_end (void)
> 
> Why is it called grub_xen_alloc_end()?
> Could we use just grub_xen_alloc()?

We could, of course. I just wanted to make clear that this function will
do the allocations needed to be at the end of the allocation process.
Naming it grub_xen_alloc() would make it occur to be a very basic
allocation function, which just isn't true. What about
grub_xen_alloc_rest()?


Juergen
Daniel Kiper Feb. 18, 2016, 5:20 p.m. UTC | #3
On Thu, Feb 18, 2016 at 01:43:33PM +0100, Juergen Gross wrote:
> On 18/02/16 12:18, Daniel Kiper wrote:
> > On Wed, Feb 17, 2016 at 06:19:35PM +0100, Juergen Gross wrote:
> >> Modern pvops linux kernels support an initrd not covered by the initial
> >> mapping. This capability is flagged by an elf-note.
> >>
> >> In case the elf-note is set by the kernel don't place the initrd into
> >> the initial mapping. This will allow to load larger initrds and/or
> >> support domains with larger memory, as the initial mapping is limited
> >> to 2GB and it is containing the p2m list.
> >>
> >> Signed-off-by: Juergen Gross <jgross@suse.com>
> >
> > One nitpick.
> >
> > Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
> >
> >> ---
> >>  grub-core/loader/i386/xen.c        | 61 ++++++++++++++++++++++++++++++--------
> >>  grub-core/loader/i386/xen_fileXX.c |  3 ++
> >>  include/grub/xen_file.h            |  1 +
> >>  3 files changed, 52 insertions(+), 13 deletions(-)
> >>
> >> diff --git a/grub-core/loader/i386/xen.c b/grub-core/loader/i386/xen.c
> >> index 3bcf4c8..7ac74f6 100644
> >> --- a/grub-core/loader/i386/xen.c
> >> +++ b/grub-core/loader/i386/xen.c
> >> @@ -58,6 +58,7 @@ struct xen_loader_state {
> >>    grub_uint64_t modules_target_start;
> >>    grub_size_t n_modules;
> >>    int loaded;
> >> +  int alloc_end_called;
> >>  };
> >>
> >>  static struct xen_loader_state xen_state;
> >> @@ -320,6 +321,28 @@ grub_xen_pt_alloc (void)
> >>  }
> >>
> >>  static grub_err_t
> >> +grub_xen_alloc_end (void)
> >
> > Why is it called grub_xen_alloc_end()?
> > Could we use just grub_xen_alloc()?
>
> We could, of course. I just wanted to make clear that this function will
> do the allocations needed to be at the end of the allocation process.
> Naming it grub_xen_alloc() would make it occur to be a very basic
> allocation function, which just isn't true. What about
> grub_xen_alloc_rest()?

My order of preference is: grub_xen_alloc_final() or grub_xen_alloc_last() or
grub_xen_alloc_end() or grub_xen_alloc_rest().

Choose one which is best for you.

Daniel
diff mbox

Patch

diff --git a/grub-core/loader/i386/xen.c b/grub-core/loader/i386/xen.c
index 3bcf4c8..7ac74f6 100644
--- a/grub-core/loader/i386/xen.c
+++ b/grub-core/loader/i386/xen.c
@@ -58,6 +58,7 @@  struct xen_loader_state {
   grub_uint64_t modules_target_start;
   grub_size_t n_modules;
   int loaded;
+  int alloc_end_called;
 };
 
 static struct xen_loader_state xen_state;
@@ -320,6 +321,28 @@  grub_xen_pt_alloc (void)
 }
 
 static grub_err_t
+grub_xen_alloc_end (void)
+{
+  grub_err_t err;
+
+  if (xen_state.alloc_end_called)
+    return GRUB_ERR_NONE;
+  xen_state.alloc_end_called = 1;
+
+  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;
+
+  return GRUB_ERR_NONE;
+}
+
+static grub_err_t
 grub_xen_boot (void)
 {
   grub_err_t err;
@@ -330,13 +353,7 @@  grub_xen_boot (void)
   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 ();
+  err = grub_xen_alloc_end ();
   if (err)
     return err;
 
@@ -609,6 +626,13 @@  grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
       goto fail;
     }
 
+  if (xen_state.xen_inf.unmapped_initrd)
+    {
+      err = grub_xen_alloc_end ();
+      if (err)
+	goto fail;
+    }
+
   if (grub_initrd_init (argc, argv, &initrd_ctx))
     goto fail;
 
@@ -626,14 +650,24 @@  grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
 	goto fail;
     }
 
-  xen_state.next_start.mod_start =
-    xen_state.max_addr + xen_state.xen_inf.virt_base;
-  xen_state.next_start.mod_len = size;
-
-  xen_state.max_addr = ALIGN_UP (xen_state.max_addr + size, PAGE_SIZE);
+  if (xen_state.xen_inf.unmapped_initrd)
+    {
+      xen_state.next_start.flags |= SIF_MOD_START_PFN;
+      xen_state.next_start.mod_start = xen_state.max_addr >> PAGE_SHIFT;
+      xen_state.next_start.mod_len = size;
+    }
+  else
+    {
+      xen_state.next_start.mod_start =
+	xen_state.max_addr + xen_state.xen_inf.virt_base;
+      xen_state.next_start.mod_len = size;
+    }
 
   grub_dprintf ("xen", "Initrd, addr=0x%x, size=0x%x\n",
-		(unsigned) xen_state.next_start.mod_start, (unsigned) size);
+		(unsigned) (xen_state.max_addr + xen_state.xen_inf.virt_base),
+		(unsigned) size);
+
+  xen_state.max_addr = ALIGN_UP (xen_state.max_addr + size, PAGE_SIZE);
 
 fail:
   grub_initrd_close (&initrd_ctx);
@@ -685,6 +719,7 @@  grub_cmd_module (grub_command_t cmd __attribute__ ((unused)),
 
   if (!xen_state.module_info_page)
     {
+      xen_state.xen_inf.unmapped_initrd = 0;
       xen_state.n_modules = 0;
       xen_state.max_addr = ALIGN_UP (xen_state.max_addr, PAGE_SIZE);
       xen_state.modules_target_start = xen_state.max_addr;
diff --git a/grub-core/loader/i386/xen_fileXX.c b/grub-core/loader/i386/xen_fileXX.c
index 1f7f71d..d68634d 100644
--- a/grub-core/loader/i386/xen_fileXX.c
+++ b/grub-core/loader/i386/xen_fileXX.c
@@ -259,6 +259,9 @@  parse_note (grub_elf_t elf, struct grub_xen_file_info *xi,
 					  descsz == 2 ? 2 : 3) == 0)
 	    xi->arch = GRUB_XEN_FILE_I386;
 	  break;
+	case XEN_ELFNOTE_MOD_START_PFN:
+	  xi->unmapped_initrd = !!grub_le_to_cpu32(*(grub_uint32_t *) desc);
+	  break;
 	default:
 	  grub_dprintf ("xen", "unknown note type %d\n", nh->n_type);
 	  break;
diff --git a/include/grub/xen_file.h b/include/grub/xen_file.h
index 4b2ccba..ed749fa 100644
--- a/include/grub/xen_file.h
+++ b/include/grub/xen_file.h
@@ -36,6 +36,7 @@  struct grub_xen_file_info
   int has_note;
   int has_xen_guest;
   int extended_cr3;
+  int unmapped_initrd;
   enum
   {
     GRUB_XEN_FILE_I386 = 1,