GRUB: Mark E820 reserved on coreboot memory

See, coreboot bug report:

https://ticket.coreboot.org/issues/590

We hadn't noticed this for quite a while, since we always
just booted with iomem=relaxed when needing to run cbmem,
since in practise it was always combined with other tasks
that require access to lower memory.

GRUB currently matches coreboot's own mmap for cbmem, but
for example SeaBIOS marks cbmem as E820 reserved. Therefore,
this change replicates the SeaBIOS behaviour.

Without this patch, Linux needs to boot with iomem=relaxed
for cbmem access, for example when running ./cbmem -1

With this patch, cbmem is now accessible regardless. This
patch also prevents Linux from overwriting parts of CBMEM.

Thanks go to Paul Menzel, who wrote this GRUB patch.

Thanks also go to Nicholas Chin, who provided testing, all
the way from Coreboot 25.03 back to Coreboot 4.20. It seems
that this is just something the payloads have to handle.

This means that both SeaBIOS and GRUB no longer have this
bug, in Libreboot; now what remains is to replicate the
test with our U-Boot payload.

Signed-off-by: Leah Rowe <leah@libreboot.org>

3 files changed, 111 insertions, 0 deletions

diff --git a/config/grub/default/patches/0014-kern-coreboot-mmap-Map-to-reserved.patch b/config/grub/default/patches/0014-kern-coreboot-mmap-Map-to-reserved.patch
new file mode 100644
index 00000000..5d93ac1d
--- /dev/null
+++ b/config/grub/default/patches/0014-kern-coreboot-mmap-Map-to-reserved.patch
@@ -0,0 +1,37 @@
+From d675307bfcac2f9e05ed119c5b5af3de48e56fb9 Mon Sep 17 00:00:00 2001
+From: Paul Menzel <pmenzel@molgen.mpg.de>
+Date: Mon, 17 May 2021 10:24:36 +0200
+Subject: [PATCH] kern/coreboot/mmap: Map to reserved
+
+https://git.savannah.gnu.org/cgit/grub.git/commit/?id=6de9ee86bf9ae50967413e6a73b5dfd13e5ffb50
+
+Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
+---
+ grub-core/kern/coreboot/mmap.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/grub-core/kern/coreboot/mmap.c b/grub-core/kern/coreboot/mmap.c
+index caf8f7cef..2fc316e8d 100644
+--- a/grub-core/kern/coreboot/mmap.c
++++ b/grub-core/kern/coreboot/mmap.c
+@@ -59,7 +59,7 @@ iterate_linuxbios_table (grub_linuxbios_table_item_t table_item, void *data)
+ 			    /* Multiboot mmaps match with the coreboot mmap
+ 			       definition.  Therefore, we can just pass type
+ 			       through.  */
+-			    mem_region->type,
++			    (mem_region->type >= 13) ? 2 : mem_region->type,
+ 			    ctx->hook_data))
+ 	    return 1;
+ 	  if (start < 0xa0000)
+@@ -81,7 +81,7 @@ iterate_linuxbios_table (grub_linuxbios_table_item_t table_item, void *data)
+ 		     /* Multiboot mmaps match with the coreboot mmap
+ 		        definition.  Therefore, we can just pass type
+ 		        through.  */
+-		     mem_region->type,
++		     (mem_region->type >= 13) ? 2 : mem_region->type,
+ 		     ctx->hook_data))
+ 	return 1;
+     }
+-- 
+2.31.1
+
diff --git a/config/grub/nvme/patches/0015-kern-coreboot-mmap-Map-to-reserved.patch b/config/grub/nvme/patches/0015-kern-coreboot-mmap-Map-to-reserved.patch
new file mode 100644
index 00000000..5d93ac1d
--- /dev/null
+++ b/config/grub/nvme/patches/0015-kern-coreboot-mmap-Map-to-reserved.patch
@@ -0,0 +1,37 @@
+From d675307bfcac2f9e05ed119c5b5af3de48e56fb9 Mon Sep 17 00:00:00 2001
+From: Paul Menzel <pmenzel@molgen.mpg.de>
+Date: Mon, 17 May 2021 10:24:36 +0200
+Subject: [PATCH] kern/coreboot/mmap: Map to reserved
+
+https://git.savannah.gnu.org/cgit/grub.git/commit/?id=6de9ee86bf9ae50967413e6a73b5dfd13e5ffb50
+
+Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
+---
+ grub-core/kern/coreboot/mmap.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/grub-core/kern/coreboot/mmap.c b/grub-core/kern/coreboot/mmap.c
+index caf8f7cef..2fc316e8d 100644
+--- a/grub-core/kern/coreboot/mmap.c
++++ b/grub-core/kern/coreboot/mmap.c
+@@ -59,7 +59,7 @@ iterate_linuxbios_table (grub_linuxbios_table_item_t table_item, void *data)
+ 			    /* Multiboot mmaps match with the coreboot mmap
+ 			       definition.  Therefore, we can just pass type
+ 			       through.  */
+-			    mem_region->type,
++			    (mem_region->type >= 13) ? 2 : mem_region->type,
+ 			    ctx->hook_data))
+ 	    return 1;
+ 	  if (start < 0xa0000)
+@@ -81,7 +81,7 @@ iterate_linuxbios_table (grub_linuxbios_table_item_t table_item, void *data)
+ 		     /* Multiboot mmaps match with the coreboot mmap
+ 		        definition.  Therefore, we can just pass type
+ 		        through.  */
+-		     mem_region->type,
++		     (mem_region->type >= 13) ? 2 : mem_region->type,
+ 		     ctx->hook_data))
+ 	return 1;
+     }
+-- 
+2.31.1
+
diff --git a/config/grub/xhci/patches/0026-kern-coreboot-mmap-Map-to-reserved.patch b/config/grub/xhci/patches/0026-kern-coreboot-mmap-Map-to-reserved.patch
new file mode 100644
index 00000000..5d93ac1d
--- /dev/null
+++ b/config/grub/xhci/patches/0026-kern-coreboot-mmap-Map-to-reserved.patch
@@ -0,0 +1,37 @@
+From d675307bfcac2f9e05ed119c5b5af3de48e56fb9 Mon Sep 17 00:00:00 2001
+From: Paul Menzel <pmenzel@molgen.mpg.de>
+Date: Mon, 17 May 2021 10:24:36 +0200
+Subject: [PATCH] kern/coreboot/mmap: Map to reserved
+
+https://git.savannah.gnu.org/cgit/grub.git/commit/?id=6de9ee86bf9ae50967413e6a73b5dfd13e5ffb50
+
+Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
+---
+ grub-core/kern/coreboot/mmap.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/grub-core/kern/coreboot/mmap.c b/grub-core/kern/coreboot/mmap.c
+index caf8f7cef..2fc316e8d 100644
+--- a/grub-core/kern/coreboot/mmap.c
++++ b/grub-core/kern/coreboot/mmap.c
+@@ -59,7 +59,7 @@ iterate_linuxbios_table (grub_linuxbios_table_item_t table_item, void *data)
+ 			    /* Multiboot mmaps match with the coreboot mmap
+ 			       definition.  Therefore, we can just pass type
+ 			       through.  */
+-			    mem_region->type,
++			    (mem_region->type >= 13) ? 2 : mem_region->type,
+ 			    ctx->hook_data))
+ 	    return 1;
+ 	  if (start < 0xa0000)
+@@ -81,7 +81,7 @@ iterate_linuxbios_table (grub_linuxbios_table_item_t table_item, void *data)
+ 		     /* Multiboot mmaps match with the coreboot mmap
+ 		        definition.  Therefore, we can just pass type
+ 		        through.  */
+-		     mem_region->type,
++		     (mem_region->type >= 13) ? 2 : mem_region->type,
+ 		     ctx->hook_data))
+ 	return 1;
+     }
+-- 
+2.31.1
+