Boot data (such as EFI related data) is not encrypted when the system is
booted because UEFI/BIOS does not run with SME active. In order to access
this data properly it needs to be mapped decrypted.
Update early_memremap() to provide an arch specific routine to modify the
pagetable protection attributes before they are applied to the new
mapping. This is used to remove the encryption mask for boot related data.
Update memremap() to provide an arch specific routine to determine if RAM
remapping is allowed. RAM remapping will cause an encrypted mapping to be
generated. By preventing RAM remapping, ioremap_cache() will be used
instead, which will provide a decrypted mapping of the boot related data.
Signed-off-by: Tom Lendacky
---
arch/x86/include/asm/io.h |5 +
arch/x86/mm/ioremap.c | 179 +
include/linux/io.h|2 +
kernel/memremap.c | 20 -
mm/early_ioremap.c| 18 -
5 files changed, 217 insertions(+), 7 deletions(-)
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 7afb0e2..09c5557 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -381,4 +381,9 @@ extern int __must_check arch_phys_wc_add(unsigned long base,
#define arch_io_reserve_memtype_wc arch_io_reserve_memtype_wc
#endif
+extern bool arch_memremap_can_ram_remap(resource_size_t offset,
+ unsigned long size,
+ unsigned long flags);
+#define arch_memremap_can_ram_remap arch_memremap_can_ram_remap
+
#endif /* _ASM_X86_IO_H */
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 4feda83..f3fa007 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -14,6 +14,7 @@
#include
#include
#include
+#include
#include
#include
@@ -22,6 +23,7 @@
#include
#include
#include
+#include
#include "physaddr.h"
@@ -422,6 +424,183 @@ void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
iounmap((void __iomem *)((unsigned long)addr & PAGE_MASK));
}
+/*
+ * Examine the physical address to determine if it is an area of memory
+ * that should be mapped decrypted. If the memory is not part of the
+ * kernel usable area it was accessed and created decrypted, so these
+ * areas should be mapped decrypted.
+ */
+static bool memremap_should_map_decrypted(resource_size_t phys_addr,
+ unsigned long size)
+{
+ /* 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_ACPI:
+ case E820_TYPE_NVS:
+ case E820_TYPE_UNUSABLE:
+ return true;
+ default:
+ break;
+ }
+
+ return false;
+}
+
+/*
+ * Examine the physical address to determine if it is EFI data. Check
+ * it against the boot params structure and EFI tables and memory types.
+ */
+static bool memremap_is_efi_data(resource_size_t phys_addr,
+unsigned long size)
+{
+ u64 paddr;
+
+ /* Check if the address is part of EFI boot/runtime data */
+ if (!efi_enabled(EFI_BOOT))
+ return false;
+
+ paddr = boot_params.efi_info.efi_memmap_hi;
+ paddr <<= 32;
+ paddr |= boot_params.efi_info.efi_memmap;
+ if (phys_addr == paddr)
+ return true;
+
+ paddr = boot_params.efi_info.efi_systab_hi;
+ paddr <<= 32;
+ paddr |= boot_params.efi_info.efi_systab;
+ if (phys_addr == paddr)
+ return true;
+
+ if (efi_is_table_address(phys_addr))
+ return true;
+
+ switch (efi_mem_type(phys_addr)) {
+ case EFI_BOOT_SERVICES_DATA:
+ case EFI_RUNTIME_SERVICES_DATA:
+ return true;
+ default:
+ break;
+ }
+
+ return false;
+}
+
+/*
+ * Examine the physical address to determine if it is boot data by checking
+ * it against the boot params setup_data chain.
+ */
+static bool memremap_is_setup_data(resource_size_t phys_addr,
+ unsigned long size)
+{
+ struct setup_data *data;
+ u64 paddr, paddr_next;
+
+ paddr = boot_params.hdr.setup_data;
+ while (paddr) {
+ unsigned int len;
+
+ if (phys_addr == paddr)
+ return true;
+
+ data = memremap(paddr, sizeof(*data),
+ MEMREMAP_WB | MEMREMAP_DEC);
+
+ paddr_next = data->next;
+ len = data->len;
+
+ memunmap(data);
+
+ if ((phys_addr > paddr) && (phys_addr < (paddr + len)))
+ return true;
+
+ paddr = paddr_next;
+ }
+
+ return false;
+}
+
+/*
+ * Examine the physical address to determine if it is boot data by checking
+ * it against the boot params se
