diff --git a/src/drivers/intel/fsp1_1/car.c b/src/drivers/intel/fsp1_1/car.c
index bd3f4787a0..84ea7d153c 100644
--- a/src/drivers/intel/fsp1_1/car.c
+++ b/src/drivers/intel/fsp1_1/car.c
@@ -14,6 +14,7 @@
  */
 
 #include <arch/symbols.h>
+#include <cbmem.h>
 #include <console/console.h>
 #include <commonlib/helpers.h>
 #include <cpu/intel/romstage.h>
@@ -32,8 +33,7 @@
 void platform_enter_postcar(void)
 {
 	struct postcar_frame pcf;
-	size_t alignment;
-	uint32_t aligned_ram;
+	uintptr_t top_of_ram;
 
 	if (postcar_frame_init(&pcf, ROMSTAGE_RAM_STACK_SIZE))
 		die("Unable to initialize postcar frame.\n");
@@ -44,53 +44,11 @@ void platform_enter_postcar(void)
 	/* Cache RAM as WB from 0 -> CACHE_TMP_RAMTOP. */
 	postcar_frame_add_mtrr(&pcf, 0, CACHE_TMP_RAMTOP, MTRR_TYPE_WRBACK);
 
-	/*
-	 *     +-------------------------+  Top of RAM (aligned)
-	 *     | System Management Mode  |
-	 *     |      code and data      |  Length: CONFIG_TSEG_SIZE
-	 *     |         (TSEG)          |
-	 *     +-------------------------+  SMM base (aligned)
-	 *     |                         |
-	 *     | Chipset Reserved Memory |  Length: Multiple of CONFIG_TSEG_SIZE
-	 *     |                         |
-	 *     +-------------------------+  top_of_ram (aligned)
-	 *     |                         |
-	 *     |       CBMEM Root        |
-	 *     |                         |
-	 *     +-------------------------+
-	 *     |                         |
-	 *     |   FSP Reserved Memory   |
-	 *     |                         |
-	 *     +-------------------------+
-	 *     |                         |
-	 *     |  Various CBMEM Entries  |
-	 *     |                         |
-	 *     +-------------------------+  top_of_stack (8 byte aligned)
-	 *     |                         |
-	 *     |   stack (CBMEM Entry)   |
-	 *     |                         |
-	 *     +-------------------------+
-	 */
-
-	alignment = mmap_region_granularity();
-	aligned_ram = ALIGN_DOWN(romstage_ram_stack_bottom(), alignment);
-	postcar_frame_add_mtrr(&pcf, aligned_ram, alignment, MTRR_TYPE_WRBACK);
-
-	if (CONFIG(HAVE_SMI_HANDLER)) {
-		void *smm_base;
-		size_t smm_size;
-
-		/*
-		 * Cache the TSEG region at the top of ram. This region is not
-		 * restricted to SMM mode until SMM has been relocated. By
-		 * setting the region to cacheable it provides faster access
-		 * when relocating the SMM handler as well as using the TSEG
-		 * region for other purposes.
-		 */
-		smm_region(&smm_base, &smm_size);
-		postcar_frame_add_mtrr(&pcf, (uintptr_t)smm_base, alignment,
-				       MTRR_TYPE_WRBACK);
-	}
+	/* Cache at least 8 MiB below the top of ram, and at most 8 MiB
+	 * above top of the ram. This satisfies MTRR alignment requirement
+	 * with different TSEG size configurations. */
+	top_of_ram = ALIGN_DOWN((uintptr_t)cbmem_top(), 8*MiB);
+	postcar_frame_add_mtrr(&pcf, top_of_ram - 8*MiB, 16*MiB, MTRR_TYPE_WRBACK);
 
 	run_postcar_phase(&pcf);
 }