diff --git a/src/soc/amd/cezanne/root_complex.c b/src/soc/amd/cezanne/root_complex.c
index 29070f6..b5bf62c 100644
--- a/src/soc/amd/cezanne/root_complex.c
+++ b/src/soc/amd/cezanne/root_complex.c
@@ -5,6 +5,7 @@
 #include <amdblocks/alib.h>
 #include <amdblocks/data_fabric.h>
 #include <amdblocks/ioapic.h>
+#include <amdblocks/iomap.h>
 #include <amdblocks/memmap.h>
 #include <arch/ioapic.h>
 #include <arch/vga.h>
@@ -151,6 +152,9 @@
 	gnb_apic->size = 0x00001000;
 	gnb_apic->flags = IORESOURCE_MEM | IORESOURCE_ASSIGNED | IORESOURCE_FIXED;
 
+	/* Reserve fixed IOMMU MMIO region */
+	mmio_range(dev, idx++, IOMMU_RESERVED_MMIO_BASE, IOMMU_RESERVED_MMIO_SIZE);
+
 	if (fsp_hob_iterator_init(&hob_iterator) != CB_SUCCESS) {
 		printk(BIOS_ERR, "%s incomplete because no HOB list was found\n",
 				__func__);
diff --git a/src/soc/amd/common/block/include/amdblocks/iomap.h b/src/soc/amd/common/block/include/amdblocks/iomap.h
index 759466b..d166a83 100644
--- a/src/soc/amd/common/block/include/amdblocks/iomap.h
+++ b/src/soc/amd/common/block/include/amdblocks/iomap.h
@@ -12,4 +12,7 @@
 #define FLASH_BELOW_4GB_MAPPING_REGION_BASE	((0xffffffff - 16 * MiB) + 1)
 #define FLASH_BELOW_4GB_MAPPING_REGION_SIZE	(16 * MiB)
 
+#define IOMMU_RESERVED_MMIO_BASE		0xfd00000000
+#define IOMMU_RESERVED_MMIO_SIZE		(4ULL * GiB)
+
 #endif /* AMD_BLOCK_IOMAP_H */
diff --git a/src/soc/amd/glinda/root_complex.c b/src/soc/amd/glinda/root_complex.c
index b18e948..1794d08 100644
--- a/src/soc/amd/glinda/root_complex.c
+++ b/src/soc/amd/glinda/root_complex.c
@@ -7,6 +7,7 @@
 #include <amdblocks/alib.h>
 #include <amdblocks/data_fabric.h>
 #include <amdblocks/ioapic.h>
+#include <amdblocks/iomap.h>
 #include <amdblocks/memmap.h>
 #include <arch/ioapic.h>
 #include <arch/vga.h>
@@ -166,6 +167,9 @@
 	gnb_apic->size = 0x00001000;
 	gnb_apic->flags = IORESOURCE_MEM | IORESOURCE_ASSIGNED | IORESOURCE_FIXED;
 
+	/* Reserve fixed IOMMU MMIO region */
+	mmio_range(dev, idx++, IOMMU_RESERVED_MMIO_BASE, IOMMU_RESERVED_MMIO_SIZE);
+
 	if (fsp_hob_iterator_init(&hob_iterator) != CB_SUCCESS) {
 		printk(BIOS_ERR, "%s incomplete because no HOB list was found\n",
 				__func__);
diff --git a/src/soc/amd/mendocino/root_complex.c b/src/soc/amd/mendocino/root_complex.c
index 7a58f01..0dcf2b8 100644
--- a/src/soc/amd/mendocino/root_complex.c
+++ b/src/soc/amd/mendocino/root_complex.c
@@ -7,6 +7,7 @@
 #include <amdblocks/alib.h>
 #include <amdblocks/data_fabric.h>
 #include <amdblocks/ioapic.h>
+#include <amdblocks/iomap.h>
 #include <amdblocks/memmap.h>
 #include <arch/ioapic.h>
 #include <arch/vga.h>
@@ -194,6 +195,9 @@
 	gnb_apic->size = 0x00001000;
 	gnb_apic->flags = IORESOURCE_MEM | IORESOURCE_ASSIGNED | IORESOURCE_FIXED;
 
+	/* Reserve fixed IOMMU MMIO region */
+	mmio_range(dev, idx++, IOMMU_RESERVED_MMIO_BASE, IOMMU_RESERVED_MMIO_SIZE);
+
 	if (fsp_hob_iterator_init(&hob_iterator) != CB_SUCCESS) {
 		printk(BIOS_ERR, "%s incomplete because no HOB list was found\n",
 				__func__);
diff --git a/src/soc/amd/phoenix/root_complex.c b/src/soc/amd/phoenix/root_complex.c
index 3110ea3..a75de50 100644
--- a/src/soc/amd/phoenix/root_complex.c
+++ b/src/soc/amd/phoenix/root_complex.c
@@ -7,6 +7,7 @@
 #include <amdblocks/alib.h>
 #include <amdblocks/data_fabric.h>
 #include <amdblocks/ioapic.h>
+#include <amdblocks/iomap.h>
 #include <amdblocks/memmap.h>
 #include <arch/ioapic.h>
 #include <arch/vga.h>
@@ -166,6 +167,9 @@
 	gnb_apic->size = 0x00001000;
 	gnb_apic->flags = IORESOURCE_MEM | IORESOURCE_ASSIGNED | IORESOURCE_FIXED;
 
+	/* Reserve fixed IOMMU MMIO region */
+	mmio_range(dev, idx++, IOMMU_RESERVED_MMIO_BASE, IOMMU_RESERVED_MMIO_SIZE);
+
 	if (fsp_hob_iterator_init(&hob_iterator) != CB_SUCCESS) {
 		printk(BIOS_ERR, "%s incomplete because no HOB list was found\n",
 				__func__);
diff --git a/src/soc/amd/picasso/root_complex.c b/src/soc/amd/picasso/root_complex.c
index cd10fdb..bf36f6dd 100644
--- a/src/soc/amd/picasso/root_complex.c
+++ b/src/soc/amd/picasso/root_complex.c
@@ -6,6 +6,7 @@
 #include <amdblocks/data_fabric.h>
 #include <amdblocks/memmap.h>
 #include <amdblocks/ioapic.h>
+#include <amdblocks/iomap.h>
 #include <arch/ioapic.h>
 #include <arch/vga.h>
 #include <assert.h>
@@ -149,6 +150,9 @@
 	gnb_apic->size = 0x00001000;
 	gnb_apic->flags = IORESOURCE_MEM | IORESOURCE_ASSIGNED | IORESOURCE_FIXED;
 
+	/* Reserve fixed IOMMU MMIO region */
+	mmio_range(dev, idx++, IOMMU_RESERVED_MMIO_BASE, IOMMU_RESERVED_MMIO_SIZE);
+
 	if (fsp_hob_iterator_init(&hob_iterator) != CB_SUCCESS) {
 		printk(BIOS_ERR, "%s incomplete because no HOB list was found\n", __func__);
 		return;