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

Brijesh Singh
2017-07-24T19:07:48Z

From: Tom Lendacky <thomas.lendacky@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.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@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