[RFC Part1 PATCH v3 08/17] x86/efi: Access EFI data as encrypted when SEV is active

[Brijesh Singh]

From: Tom Lendacky <thomas.lenda...@amd.com>

EFI data is encrypted when the kernel is run under SEV. Update the
page table references to be sure the EFI memory areas are accessed
encrypted.

Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
Signed-off-by: Brijesh Singh <brijesh.si...@amd.com>
---
 arch/x86/platform/efi/efi_64.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 12e8388..1ecb3f6 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -32,6 +32,7 @@
 #include <linux/reboot.h>
 #include <linux/slab.h>
 #include <linux/ucs2_string.h>
+#include <linux/mem_encrypt.h>
 
 #include <asm/setup.h>
 #include <asm/page.h>
@@ -369,7 +370,10 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, 
unsigned num_pages)
         * as trim_bios_range() will reserve the first page and isolate it away
         * from memory allocators anyway.
         */
-       if (kernel_map_pages_in_pgd(pgd, 0x0, 0x0, 1, _PAGE_RW)) {
+       pf = _PAGE_RW;
+       if (sev_active())
+               pf |= _PAGE_ENC;
+       if (kernel_map_pages_in_pgd(pgd, 0x0, 0x0, 1, pf)) {
                pr_err("Failed to create 1:1 mapping for the first page!\n");
                return 1;
        }
@@ -412,6 +416,9 @@ static void __init __map_region(efi_memory_desc_t *md, u64 
va)
        if (!(md->attribute & EFI_MEMORY_WB))
                flags |= _PAGE_PCD;
 
+       if (sev_active())
+               flags |= _PAGE_ENC;
+
        pfn = md->phys_addr >> PAGE_SHIFT;
        if (kernel_map_pages_in_pgd(pgd, pfn, va, md->num_pages, flags))
                pr_warn("Error mapping PA 0x%llx -> VA 0x%llx!\n",
@@ -511,6 +518,9 @@ static int __init efi_update_mappings(efi_memory_desc_t 
*md, unsigned long pf)
        pgd_t *pgd = efi_pgd;
        int err1, err2;
 
+       if (sev_active())
+               pf |= _PAGE_ENC;
+
        /* Update the 1:1 mapping */
        pfn = md->phys_addr >> PAGE_SHIFT;
        err1 = kernel_map_pages_in_pgd(pgd, pfn, md->phys_addr, md->num_pages, 
pf);
@@ -589,6 +599,9 @@ void __init efi_runtime_update_mappings(void)
                        (md->type != EFI_RUNTIME_SERVICES_CODE))
                        pf |= _PAGE_RW;
 
+               if (sev_active())
+                       pf |= _PAGE_ENC;
+
                efi_update_mappings(md, pf);
        }
 }
-- 
2.9.4