diff --git a/arch/x86/include/asm/e820/types.h b/arch/x86/include/asm/e820/types.h
index 314f75d886d0..d91d4d28fe50 100644
--- a/arch/x86/include/asm/e820/types.h
+++ b/arch/x86/include/asm/e820/types.h
@@ -44,6 +44,9 @@ enum e820_type {
 	 * might alter over the S3 transition:
 	 */
 	E820_TYPE_RESERVED_KERN	= 128,
+
+	/* Used for EFI_MEMORY_MAPPED_IO when translating the EFI memmap */
+	E820_TYPE_MMIO = 129,
 };
 
 /*
diff --git a/arch/x86/include/asm/iommu.h b/arch/x86/include/asm/iommu.h
index bf1ed2ddc74b..ed7329137fef 100644
--- a/arch/x86/include/asm/iommu.h
+++ b/arch/x86/include/asm/iommu.h
@@ -18,7 +18,8 @@ arch_rmrr_sanity_check(struct acpi_dmar_reserved_memory *rmrr)
 	u64 start = rmrr->base_address;
 	u64 end = rmrr->end_address + 1;
 
-	if (e820__mapped_all(start, end, E820_TYPE_RESERVED))
+	if (e820__mapped_all(start, end, E820_TYPE_RESERVED) ||
+	    e820__mapped_all(start, end, E820_TYPE_MMIO))
 		return 0;
 
 	pr_err(FW_BUG "No firmware reserved region can cover this RMRR [%#018Lx-%#018Lx], contact BIOS vendor for fixes\n",
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index bc0657f0deed..5fbd2505b10e 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -196,6 +196,7 @@ static void __init e820_print_type(enum e820_type type)
 	case E820_TYPE_UNUSABLE:	pr_cont("unusable");			break;
 	case E820_TYPE_PMEM:		/* Fall through: */
 	case E820_TYPE_PRAM:		pr_cont("persistent (type %u)", type);	break;
+	case E820_TYPE_MMIO:		pr_cont("MMIO");			break;
 	default:			pr_cont("type %u", type);		break;
 	}
 }
@@ -1064,6 +1065,7 @@ static const char *__init e820_type_to_string(struct e820_entry *entry)
 	case E820_TYPE_PMEM:		return "Persistent Memory";
 	case E820_TYPE_RESERVED:	return "Reserved";
 	case E820_TYPE_SOFT_RESERVED:	return "Soft Reserved";
+	case E820_TYPE_MMIO:		return "Memory Mapped IO";
 	default:			return "Unknown E820 type";
 	}
 }
@@ -1080,6 +1082,7 @@ static unsigned long __init e820_type_to_iomem_type(struct e820_entry *entry)
 	case E820_TYPE_PMEM:		/* Fall-through: */
 	case E820_TYPE_RESERVED:	/* Fall-through: */
 	case E820_TYPE_SOFT_RESERVED:	/* Fall-through: */
+	case E820_TYPE_MMIO:		/* Fall-through: */
 	default:			return IORESOURCE_MEM;
 	}
 }
@@ -1091,6 +1094,7 @@ static unsigned long __init e820_type_to_iores_desc(struct e820_entry *entry)
 	case E820_TYPE_NVS:		return IORES_DESC_ACPI_NV_STORAGE;
 	case E820_TYPE_PMEM:		return IORES_DESC_PERSISTENT_MEMORY;
 	case E820_TYPE_PRAM:		return IORES_DESC_PERSISTENT_MEMORY_LEGACY;
+	case E820_TYPE_MMIO:		/* Fall-through: */
 	case E820_TYPE_RESERVED:	return IORES_DESC_RESERVED;
 	case E820_TYPE_SOFT_RESERVED:	return IORES_DESC_SOFT_RESERVED;
 	case E820_TYPE_RESERVED_KERN:	/* Fall-through: */
@@ -1113,6 +1117,7 @@ static bool __init do_mark_busy(enum e820_type type, struct resource *res)
 	switch (type) {
 	case E820_TYPE_RESERVED:
 	case E820_TYPE_SOFT_RESERVED:
+	case E820_TYPE_MMIO:
 	case E820_TYPE_PRAM:
 	case E820_TYPE_PMEM:
 		return false;
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 026031b3b782..7987e9c899fa 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -552,6 +552,7 @@ static bool memremap_should_map_decrypted(resource_size_t phys_addr,
 	/* Check if the address is outside kernel usable area */
 	switch (e820__get_entry_type(phys_addr, phys_addr + size - 1)) {
 	case E820_TYPE_RESERVED:
+	case E820_TYPE_MMIO:
 	case E820_TYPE_ACPI:
 	case E820_TYPE_NVS:
 	case E820_TYPE_UNUSABLE:
diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c
index 758cbfe55daa..3c19353bae10 100644
--- a/arch/x86/pci/mmconfig-shared.c
+++ b/arch/x86/pci/mmconfig-shared.c
@@ -425,7 +425,7 @@ static acpi_status find_mboard_resource(acpi_handle handle, u32 lvl,
 	return AE_OK;
 }
 
-static bool is_acpi_reserved(u64 start, u64 end, enum e820_type not_used)
+static bool is_acpi_reserved(u64 start, u64 end)
 {
 	struct resource mcfg_res;
 
@@ -442,7 +442,14 @@ static bool is_acpi_reserved(u64 start, u64 end, enum e820_type not_used)
 	return mcfg_res.flags;
 }
 
-typedef bool (*check_reserved_t)(u64 start, u64 end, enum e820_type type);
+static bool is_e820_reserved(u64 start, u64 end)
+{
+	int type = e820__get_entry_type(start, end);
+
+	return type == E820_TYPE_RESERVED || type == E820_TYPE_MMIO;
+}
+
+typedef bool (*check_reserved_t)(u64 start, u64 end);
 
 static bool __ref is_mmconf_reserved(check_reserved_t is_reserved,
 				     struct pci_mmcfg_region *cfg,
@@ -454,7 +461,7 @@ static bool __ref is_mmconf_reserved(check_reserved_t is_reserved,
 	int num_buses;
 	char *method = with_e820 ? "E820" : "ACPI motherboard resources";
 
-	while (!is_reserved(addr, addr + size, E820_TYPE_RESERVED)) {
+	while (!is_reserved(addr, addr + size)) {
 		size >>= 1;
 		if (size < (16UL<<20))
 			break;
@@ -527,7 +534,7 @@ pci_mmcfg_check_reserved(struct device *dev, struct pci_mmcfg_region *cfg, int e
 	/* Don't try to do this check unless configuration
 	   type 1 is available. how about type 2 ?*/
 	if (raw_pci_ops)
-		return is_mmconf_reserved(e820__mapped_all, cfg, dev, 1);
+		return is_mmconf_reserved(is_e820_reserved, cfg, dev, 1);
 
 	return false;
 }
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 147c30a81f15..23b361447417 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -173,10 +173,13 @@ static void __init do_add_efi_memmap(void)
 		case EFI_PERSISTENT_MEMORY:
 			e820_type = E820_TYPE_PMEM;
 			break;
+		case EFI_MEMORY_MAPPED_IO:
+			e820_type = E820_TYPE_MMIO;
+			break;
 		default:
 			/*
 			 * EFI_RESERVED_TYPE EFI_RUNTIME_SERVICES_CODE
-			 * EFI_RUNTIME_SERVICES_DATA EFI_MEMORY_MAPPED_IO
+			 * EFI_RUNTIME_SERVICES_DATA
 			 * EFI_MEMORY_MAPPED_IO_PORT_SPACE EFI_PAL_CODE
 			 */
 			e820_type = E820_TYPE_RESERVED;
diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
index 01ddd4502e28..d0795adc2534 100644
--- a/drivers/firmware/efi/libstub/x86-stub.c
+++ b/drivers/firmware/efi/libstub/x86-stub.c
@@ -470,12 +470,15 @@ setup_e820(struct boot_params *params, struct setup_data *e820ext, u32 e820ext_s
 		case EFI_RESERVED_TYPE:
 		case EFI_RUNTIME_SERVICES_CODE:
 		case EFI_RUNTIME_SERVICES_DATA:
-		case EFI_MEMORY_MAPPED_IO:
 		case EFI_MEMORY_MAPPED_IO_PORT_SPACE:
 		case EFI_PAL_CODE:
 			e820_type = E820_TYPE_RESERVED;
 			break;
 
+		case EFI_MEMORY_MAPPED_IO:
+			e820_type = E820_TYPE_MMIO;
+			break;
+
 		case EFI_UNUSABLE_MEMORY:
 			e820_type = E820_TYPE_UNUSABLE;
 			break;
