[PATCHv2 52/59] x86/mm: Disable MKTME if not all system memory supports encryption

Kirill A. Shutemov
2019-07-31T15:23:51Z

UEFI memory attribute EFI_MEMORY_CPU_CRYPTO indicates whether the memory
region supports encryption.

Kernel doesn't handle situation when only part of the system memory
supports encryption.

Disable MKTME if not all system memory supports encryption.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/mm/mktme.c | 35 +++++++++++++++++++++++++++++++++++
drivers/firmware/efi/efi.c | 25 +++++++++++++------------
include/linux/efi.h | 1 +
3 files changed, 49 insertions(+), 12 deletions(-)

diff --git a/arch/x86/mm/mktme.c b/arch/x86/mm/mktme.c
index 17366d81c21b..4e00c244478b 100644
--- a/arch/x86/mm/mktme.c
+++ b/arch/x86/mm/mktme.c
@@ -1,9 +1,11 @@
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/rmap.h>
+#include <linux/efi.h>
#include <asm/mktme.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
+#include <asm/e820/api.h>

/* Mask to extract KeyID from physical address. */
phys_addr_t __mktme_keyid_mask;
@@ -48,9 +50,42 @@ void mktme_disable(void)

static bool need_page_mktme(void)
{
+ int nid;
+
/* Make sure keyid doesn't collide with extended page flags */
BUILD_BUG_ON(__NR_PAGE_EXT_FLAGS > 16);

+ if (!mktme_nr_keyids())
+ return 0;
+
+ for_each_node_state(nid, N_MEMORY) {
+ const efi_memory_desc_t *md;
+ unsigned long node_start, node_end;
+
+ node_start = node_start_pfn(nid) << PAGE_SHIFT;
+ node_end = node_end_pfn(nid) << PAGE_SHIFT;
+
+ for_each_efi_memory_desc(md) {
+ u64 efi_start = md->phys_addr;
+ u64 efi_end = md->phys_addr + PAGE_SIZE * md->num_pages;
+
+ if (md->attribute & EFI_MEMORY_CPU_CRYPTO)
+ continue;
+ if (efi_start > node_end)
+ continue;
+ if (efi_end < node_start)
+ continue;
+ if (!e820__mapped_any(efi_start, efi_end, E820_TYPE_RAM))
+ continue;
+
+ printk("Memory range %#llx-%#llx: doesn't support encryption\n",
+ efi_start, efi_end);
+ printk("Disable MKTME\n");
+ mktme_disable();
+ break;
+ }
+ }
+
return !!mktme_nr_keyids();
}

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index ad3b1f4866b3..fc19da5da3e8 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -852,25 +852,26 @@ char * __init efi_md_typeattr_format(char *buf, size_t size,
if (attr & ~(EFI_MEMORY_UC | EFI_MEMORY_WC | EFI_MEMORY_WT |
EFI_MEMORY_WB | EFI_MEMORY_UCE | EFI_MEMORY_RO |
EFI_MEMORY_WP | EFI_MEMORY_RP | EFI_MEMORY_XP |
- EFI_MEMORY_NV |
+ EFI_MEMORY_NV | EFI_MEMORY_CPU_CRYPTO |
EFI_MEMORY_RUNTIME | EFI_MEMORY_MORE_RELIABLE))
snprintf(pos, size, "|attr=0x%016llx]",
(unsigned long long)attr);
else
snprintf(pos, size,
- "|%3s|%2s|%2s|%2s|%2s|%2s|%2s|%3s|%2s|%2s|%2s|%2s]",
+ "|%3s|%2s|%2s|%2s|%2s|%2s|%2s|%2s|%3s|%2s|%2s|%2s|%2s]",
attr & EFI_MEMORY_RUNTIME ? "RUN" : "",
attr & EFI_MEMORY_MORE_RELIABLE ? "MR" : "",
- attr & EFI_MEMORY_NV ? "NV" : "",
- attr & EFI_MEMORY_XP ? "XP" : "",
- attr & EFI_MEMORY_RP ? "RP" : "",
- attr & EFI_MEMORY_WP ? "WP" : "",
- attr & EFI_MEMORY_RO ? "RO" : "",
- attr & EFI_MEMORY_UCE ? "UCE" : "",
- attr & EFI_MEMORY_WB ? "WB" : "",
- attr & EFI_MEMORY_WT ? "WT" : "",
- attr & EFI_MEMORY_WC ? "WC" : "",
- attr & EFI_MEMORY_UC ? "UC" : "");
+ attr & EFI_MEMORY_NV ? "NV" : "",
+ attr & EFI_MEMORY_CPU_CRYPTO ? "CR" : "",
+ attr & EFI_MEMORY_XP ? "XP" : "",
+ attr & EFI_MEMORY_RP ? "RP" : "",
+ attr & EFI_MEMORY_WP ? "WP" : "",
+ attr & EFI_MEMORY_RO ? "RO" : "",
+ attr & EFI_MEMORY_UCE ? "UCE" : "",
+ attr & EFI_MEMORY_WB ? "WB" : "",
+ attr & EFI_MEMORY_WT ? "WT" : "",
+ attr & EFI_MEMORY_WC ? "WC" : "",
+ attr & EFI_MEMORY_UC ? "UC" : "");
return buf;
}

diff --git a/include/linux/efi.h b/include/linux/efi.h
index f87fabea4a85..4ac54a168ffe 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -112,6 +112,7 @@ typedef struct {
#define EFI_MEMORY_MORE_RELIABLE \
((u64)0x0000000000010000ULL) /* higher reliability */
#define EFI_MEMORY_RO ((u64)0x0000000000020000ULL) /* read-only */
+#define EFI_MEMORY_CPU_CRYPTO ((u64)0x0000000000080000ULL) /* memory encryption supported */
#define EFI_MEMORY_RUNTIME ((u64)0x8000000000000000ULL) /* range requires runtime mapping */
#define EFI_MEMORY_DESCRIPTOR_VERSION 1

--
2.21.0