diff --git a/src/northbridge/intel/haswell/memmap.c b/src/northbridge/intel/haswell/memmap.c
index 807ee2a..ac36e25 100644
--- a/src/northbridge/intel/haswell/memmap.c
+++ b/src/northbridge/intel/haswell/memmap.c
@@ -9,27 +9,56 @@
 #include <cpu/x86/smm.h>
 #include <device/pci_ops.h>
 #include <cbmem.h>
+#include <security/intel/txt/txt_register.h>
+
 #include "haswell.h"
 
-static uintptr_t smm_region_start(void)
+static uintptr_t northbridge_get_tseg_base(void)
+{
+	return ALIGN_DOWN(pci_read_config32(HOST_BRIDGE, TSEG), 1 * MiB);
+}
+
+static size_t northbridge_get_tseg_size(void)
+{
+	return CONFIG_SMM_TSEG_SIZE;
+}
+
+/*
+ * Return the topmost memory address below 4 GiB available for general
+ * use, from software's view of memory. Do not confuse this with TOLUD,
+ * which applies to the DRAM as viewed by the memory controller itself.
+ */
+static uintptr_t top_of_low_usable_memory(void)
 {
 	/*
-	 * Base of TSEG is top of usable DRAM below 4GiB. The register has
-	 * 1 MiB alignment.
+	 * Base of DPR is top of usable DRAM below 4 GiB. However, DPR
+	 * isn't always enabled. Unlike most memory map registers, the
+	 * DPR register stores top of DPR instead of its base address.
+	 * Unless binary-patched, Haswell MRC.bin does not enable DPR.
+	 * Top of DPR is R/O, and mirrored from TSEG base by hardware.
 	 */
-	uintptr_t tom = pci_read_config32(HOST_BRIDGE, TSEG);
-	return ALIGN_DOWN(tom, 1 * MiB);
+	uintptr_t tolum = northbridge_get_tseg_base();
+
+	const union dpr_register dpr = {
+		.raw = pci_read_config32(HOST_BRIDGE, DPR),
+	};
+
+	/* Subtract DMA Protected Range size if enabled */
+	if (dpr.epm)
+		tolum -= dpr.size * MiB;
+
+	return tolum;
 }
 
 void *cbmem_top_chipset(void)
 {
-	return (void *)smm_region_start();
+	return (void *)top_of_low_usable_memory();
 }
 
 void smm_region(uintptr_t *start, size_t *size)
 {
-	*start = smm_region_start();
-	*size = CONFIG_SMM_TSEG_SIZE;
+	*start = northbridge_get_tseg_base();
+	*size = northbridge_get_tseg_size();
 }
 
 void fill_postcar_frame(struct postcar_frame *pcf)
diff --git a/src/northbridge/intel/haswell/northbridge.c b/src/northbridge/intel/haswell/northbridge.c
index e1c26d1..5619d95 100644
--- a/src/northbridge/intel/haswell/northbridge.c
+++ b/src/northbridge/intel/haswell/northbridge.c
@@ -12,6 +12,7 @@
 #include <device/pci_ids.h>
 #include <device/pci_ops.h>
 #include <boot/tables.h>
+#include <security/intel/txt/txt_register.h>
 
 #include "chip.h"
 #include "haswell.h"
@@ -162,7 +163,8 @@
 	}
 }
 
-/* Host Memory Map:
+/*
+ * Host Memory Map:
  *
  * +--------------------------+ TOUUD
  * |                          |
@@ -175,6 +177,8 @@
  * +--------------------------+ BGSM
  * |     TSEG                 |
  * +--------------------------+ TSEGMB
+ * |     DPR                  |
+ * +--------------------------+ (DPR top - DPR size)
  * |     Usage DRAM           |
  * +--------------------------+ 0
  *
@@ -285,6 +289,12 @@
 	mc_read_map_entries(dev, &mc_values[0]);
 	mc_report_map_entries(dev, &mc_values[0]);
 
+	/* The DPR register is special */
+	const union dpr_register dpr = {
+		.raw = pci_read_config32(dev, DPR),
+	};
+	printk(BIOS_DEBUG, "MC MAP: DPR: 0x%x\n", dpr.raw);
+
 	/*
 	 * These are the host memory ranges that should be added:
 	 * - 0 -> 0xa0000:    cacheable
@@ -318,11 +328,20 @@
 	size_k = (0xa0000 >> 10) - base_k;
 	ram_resource(dev, index++, base_k, size_k);
 
-	/* 0xc0000 -> TSEG */
+	/* 0xc0000 -> DPR base */
 	base_k = 0xc0000 >> 10;
-	size_k = (unsigned long)(mc_values[TSEG_REG] >> 10) - base_k;
+	size_k = (unsigned long)(mc_values[TSEG_REG] >> 10) - (base_k + dpr.size);
 	ram_resource(dev, index++, base_k, size_k);
 
+	/* DPR base -> TSEG */
+	if (dpr.size) {
+		resource = new_resource(dev, index++);
+		resource->base = (dpr.top - dpr.size) * MiB;
+		resource->size = dpr.size * MiB;
+		resource->flags = IORESOURCE_MEM | IORESOURCE_STORED | IORESOURCE_CACHEABLE |
+				  IORESOURCE_RESERVE | IORESOURCE_ASSIGNED | IORESOURCE_FIXED;
+	}
+
 	/* TSEG -> BGSM */
 	resource = new_resource(dev, index++);
 	resource->base = mc_values[TSEG_REG];
diff --git a/src/northbridge/intel/haswell/registers/host_bridge.h b/src/northbridge/intel/haswell/registers/host_bridge.h
index d348fd4..7746801 100644
--- a/src/northbridge/intel/haswell/registers/host_bridge.h
+++ b/src/northbridge/intel/haswell/registers/host_bridge.h
@@ -25,6 +25,9 @@
 
 #define PAVPC		0x58
 #define DPR		0x5c
+#define  DPR_EPM	(1 << 2)
+#define  DPR_PRS	(1 << 1)
+#define  DPR_SIZE_MASK	0xff0
 
 #define PCIEXBAR	0x60
 #define DMIBAR		0x68