x86/xen/efi: Initialize only the EFI struct members used by Xen

The current approach, which is the wholesale efi struct initialization from
a 'efi_xen' local template is not robust. Usually if new member is defined
then it is properly initialized in drivers/firmware/efi/efi.c, but not in
arch/x86/xen/efi.c.

The effect is that the Xen initialization clears any fields the generic code
might have set and the Xen code does not know about yet.

I saw this happen a few times, so let's initialize only the EFI struct members
used by Xen and maintain no local duplicate, to avoid such issues in the future.

Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: andrew.cooper3@citrix.com
Cc: jgross@suse.com
Cc: linux-efi@vger.kernel.org
Cc: matt@codeblueprint.co.uk
Cc: stable@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1498128697-12943-3-git-send-email-daniel.kiper@oracle.com
[ Clarified the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 12 insertions, 33 deletions

diff --git a/arch/x86/xen/efi.c b/arch/x86/xen/efi.c
index 30bb2e80cfe7..a18703be9ead 100644
--- a/arch/x86/xen/efi.c
+++ b/arch/x86/xen/efi.c
@@ -54,38 +54,6 @@ static efi_system_table_t efi_systab_xen __initdata = {
         .tables         = EFI_INVALID_TABLE_ADDR  /* Initialized later. */
 };
 
-static const struct efi efi_xen __initconst = {
-        .systab                   = NULL, /* Initialized later. */
-        .runtime_version          = 0,    /* Initialized later. */
-        .mps                      = EFI_INVALID_TABLE_ADDR,
-        .acpi                     = EFI_INVALID_TABLE_ADDR,
-        .acpi20                   = EFI_INVALID_TABLE_ADDR,
-        .smbios                   = EFI_INVALID_TABLE_ADDR,
-        .smbios3                  = EFI_INVALID_TABLE_ADDR,
-        .sal_systab               = EFI_INVALID_TABLE_ADDR,
-        .boot_info                = EFI_INVALID_TABLE_ADDR,
-        .hcdp                     = EFI_INVALID_TABLE_ADDR,
-        .uga                      = EFI_INVALID_TABLE_ADDR,
-        .uv_systab                = EFI_INVALID_TABLE_ADDR,
-        .fw_vendor                = EFI_INVALID_TABLE_ADDR,
-        .runtime                  = EFI_INVALID_TABLE_ADDR,
-        .config_table             = EFI_INVALID_TABLE_ADDR,
-        .get_time                 = xen_efi_get_time,
-        .set_time                 = xen_efi_set_time,
-        .get_wakeup_time          = xen_efi_get_wakeup_time,
-        .set_wakeup_time          = xen_efi_set_wakeup_time,
-        .get_variable             = xen_efi_get_variable,
-        .get_next_variable        = xen_efi_get_next_variable,
-        .set_variable             = xen_efi_set_variable,
-        .query_variable_info      = xen_efi_query_variable_info,
-        .update_capsule           = xen_efi_update_capsule,
-        .query_capsule_caps       = xen_efi_query_capsule_caps,
-        .get_next_high_mono_count = xen_efi_get_next_high_mono_count,
-        .reset_system             = xen_efi_reset_system,
-        .set_virtual_address_map  = NULL, /* Not used under Xen. */
-        .flags                    = 0     /* Initialized later. */
-};
-
 static efi_system_table_t __init *xen_efi_probe(void)
 {
         struct xen_platform_op op = {
@@ -102,7 +70,18 @@ static efi_system_table_t __init *xen_efi_probe(void)
 
         /* Here we know that Xen runs on EFI platform. */
 
-        efi = efi_xen;
+        efi.get_time                 = xen_efi_get_time;
+        efi.set_time                 = xen_efi_set_time;
+        efi.get_wakeup_time          = xen_efi_get_wakeup_time;
+        efi.set_wakeup_time          = xen_efi_set_wakeup_time;
+        efi.get_variable             = xen_efi_get_variable;
+        efi.get_next_variable        = xen_efi_get_next_variable;
+        efi.set_variable             = xen_efi_set_variable;
+        efi.query_variable_info      = xen_efi_query_variable_info;
+        efi.update_capsule           = xen_efi_update_capsule;
+        efi.query_capsule_caps       = xen_efi_query_capsule_caps;
+        efi.get_next_high_mono_count = xen_efi_get_next_high_mono_count;
+        efi.reset_system             = xen_efi_reset_system;
 
         efi_systab_xen.tables = info->cfg.addr;
         efi_systab_xen.nr_tables = info->cfg.nent;