src/soc/intel/common: Make top_of_ram till TOLUD region mmio_resource

Ideally don't need to mark the entire top_of_ram till TOLUD range (used
for stolen memory like GFX and ME, PTT, DPR, PRMRR, TSEG etc) as
cacheable for OS usage as coreboot already done with mpinit w/ smm
relocation early.

TEST=Able to build and boot ICL, TGL RVP.

Without this CL :

PCI: 00:00.0 resource base 77000000 size 4800000 align 0 gran 0 limit 0 flags f0004200 index 9
PCI: 00:00.0 resource base 7b800000 size 4400000 align 0 gran 0 limit 0 flags f0000200 index a

With this CL :

PCI: 00:00.0 resource base 77000000 size 8c00000 align 0 gran 0 limit 0 flags f0000200 index 9

No changes observed with MTRRs snapshot.

Change-Id: I64c14b14caf0a53219fdc02ec6bbd375955a0c8e
Signed-off-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44014
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Maulik V Vaghela <maulik.v.vaghela@intel.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

1 files changed, 6 insertions, 11 deletions

diff --git a/src/soc/intel/common/block/systemagent/systemagent.c b/src/soc/intel/common/block/systemagent/systemagent.c
index 195a8e7a5c..39ac53f13c 100644
--- a/src/soc/intel/common/block/systemagent/systemagent.c
+++ b/src/soc/intel/common/block/systemagent/systemagent.c
@@ -158,8 +158,7 @@ static void sa_get_mem_map(struct device *dev, uint64_t *values)
  * These are the host memory ranges that should be added:
  * - 0 -> 0xa0000: cacheable
  * - 0xc0000 -> top_of_ram : cacheable
- * - top_of_ram -> BGSM: cacheable with standard MTRRs and reserved
- * - BGSM -> TOLUD: not cacheable with standard MTRRs and reserved
+ * - top_of_ram -> TOLUD: not cacheable with standard MTRRs and reserved
  * - 4GiB -> TOUUD: cacheable
  *
  * The default SMRAM space is reserved so that the range doesn't
@@ -173,9 +172,10 @@ static void sa_get_mem_map(struct device *dev, uint64_t *values)
  * is not omitted the mtrr code will setup the area as cacheable
  * causing VGA access to not work.
  *
- * The TSEG region is mapped as cacheable so that one can perform
- * SMRAM relocation faster. Once the SMRR is enabled the SMRR takes
- * precedence over the existing MTRRs covering this region.
+ * Don't need to mark the entire top_of_ram till TOLUD range (used
+ * for stolen memory like GFX and ME, PTT, DPR, PRMRR, TSEG etc) as
+ * cacheable for OS usage as coreboot already done with mpinit w/ smm
+ * relocation early.
  *
  * It should be noted that cacheable entry types need to be added in
  * order. The reason is that the current MTRR code assumes this and
@@ -206,13 +206,8 @@ static void sa_add_dram_resources(struct device *dev, int *resource_count)
 
 	sa_get_mem_map(dev, &sa_map_values[0]);
 
-	/* top_of_ram -> BGSM */
+	/* top_of_ram -> TOLUD */
 	base_k = top_of_ram;
-	size_k = sa_map_values[SA_BGSM_REG] - base_k;
-	reserved_ram_resource(dev, index++, base_k / KiB, size_k / KiB);
-
-	/* BGSM -> TOLUD */
-	base_k = sa_map_values[SA_BGSM_REG];
 	size_k = sa_map_values[SA_TOLUD_REG] - base_k;
 	mmio_resource(dev, index++, base_k / KiB, size_k / KiB);