[Xen-devel] [PATCH] x86/efi: Reserve EFI properties table

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

Some EFI firmware implementations may place the EFI properties table in
RAM marked as BootServicesData, which Xen does not consider as reserved.
When dom0 tries to access the EFI properties table (which Linux >= 4.4
does), it crashes with a page fault.  Fix this by unconditionally
marking the EFI properties table as reserved in the E820, much like is
done with the dmi regions.

Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
---
 xen/arch/x86/efi/efi-boot.h |  8 ++++++++
 xen/common/efi/boot.c       | 20 ++++++++++++++++++++
 xen/common/efi/efi.h        |  4 ++++
 3 files changed, 32 insertions(+)

diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h
index 34537d4..36ae464 100644
--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -209,6 +209,14 @@ static void __init 
efi_arch_process_memory_map(EFI_SYSTEM_TABLE *SystemTable,
         }
     }
 
+    if ( efi_properties_tbl_addr && efi_properties_tbl_size )
+    {
+        ++e;
+        e->addr = efi_properties_tbl_addr;
+        e->size = efi_properties_tbl_size;
+        e->type = E820_RESERVED;
+        ++e820_raw.nr_map;
+    }
 }
 
 static void *__init efi_arch_allocate_mmap_buffer(UINTN map_size)
diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index daf0c80..1fb396b 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -40,6 +40,8 @@
   { 0x605dab50, 0xe046, 0x4300, {0xab, 0xb6, 0x3d, 0xd8, 0x10, 0xdd, 0x8b, 
0x23} }
 #define APPLE_PROPERTIES_PROTOCOL_GUID \
   { 0x91bd12fe, 0xf6c3, 0x44fb, { 0xa5, 0xb7, 0x51, 0x22, 0xab, 0x30, 0x3a, 
0xe0} }
+#define EFI_PROPERTIES_TABLE_GUID \
+  { 0x880aaca3, 0x4adc, 0x4a04, { 0x90, 0x79, 0xb7, 0x47, 0x34, 0x08, 0x25, 
0xe5} }
 
 typedef EFI_STATUS
 (/* _not_ EFIAPI */ *EFI_SHIM_LOCK_VERIFY) (
@@ -171,6 +173,15 @@ static char __section(".bss.page_aligned") 
__aligned(PAGE_SIZE)
     ebmalloc_mem[EBMALLOC_SIZE];
 static unsigned long __initdata ebmalloc_allocated;
 
+struct efi_properties_table {
+    u32 version;
+    u32 length;
+    u64 memory_protection_attribute;
+};
+
+u64 __initdata efi_properties_tbl_addr;
+u32 __initdata efi_properties_tbl_size;
+
 /* EFI boot allocator. */
 static void __init __maybe_unused *ebmalloc(size_t size)
 {
@@ -809,6 +820,7 @@ static void __init efi_tables(void)
         static EFI_GUID __initdata mps_guid = MPS_TABLE_GUID;
         static EFI_GUID __initdata smbios_guid = SMBIOS_TABLE_GUID;
         static EFI_GUID __initdata smbios3_guid = SMBIOS3_TABLE_GUID;
+        static EFI_GUID __initdata properties_guid = EFI_PROPERTIES_TABLE_GUID;
 
         if ( match_guid(&acpi2_guid, &efi_ct[i].VendorGuid) )
               efi.acpi20 = (long)efi_ct[i].VendorTable;
@@ -820,6 +832,14 @@ static void __init efi_tables(void)
               efi.smbios = (long)efi_ct[i].VendorTable;
         if ( match_guid(&smbios3_guid, &efi_ct[i].VendorGuid) )
               efi.smbios3 = (long)efi_ct[i].VendorTable;
+        if ( match_guid(&properties_guid, &efi_ct[i].VendorGuid) )
+        {
+            struct efi_properties_table *properties;
+
+            efi_properties_tbl_addr = (long)efi_ct[i].VendorTable;
+            properties = (struct efi_properties_table 
*)efi_properties_tbl_addr;
+            efi_properties_tbl_size = properties->length;
+        }
     }
 
 #ifndef CONFIG_ARM /* TODO - disabled until implemented on ARM */
diff --git a/xen/common/efi/efi.h b/xen/common/efi/efi.h
index 6b9c56e..e509111 100644
--- a/xen/common/efi/efi.h
+++ b/xen/common/efi/efi.h
@@ -5,6 +5,7 @@
 #include <efi/efidevp.h>
 #include <efi/eficapsule.h>
 #include <efi/efiapi.h>
+#include <xen/init.h>
 #include <xen/efi.h>
 #include <xen/spinlock.h>
 #include <asm/page.h>
@@ -39,3 +40,6 @@ extern UINT64 efi_boot_max_var_store_size, 
efi_boot_remain_var_store_size,
 
 extern UINT64 efi_apple_properties_addr;
 extern UINTN efi_apple_properties_len;
+
+extern u64 __initdata efi_properties_tbl_addr;
+extern u32 __initdata efi_properties_tbl_size;
-- 
2.7.4


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