[Xen-devel] [PATCH 4.12 26/84] x86/xen/efi: Initialize only the EFI struct members used by Xen

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Daniel Kiper <daniel.kiper@xxxxxxxxxx>

commit 6c64447ec58b0bac612732303f7ab04562124587 upstream.

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@xxxxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Acked-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: andrew.cooper3@xxxxxxxxxx
Cc: jgross@xxxxxxxx
Cc: linux-efi@xxxxxxxxxxxxxxx
Cc: matt@xxxxxxxxxxxxxxxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
Link: 
http://lkml.kernel.org/r/1498128697-12943-3-git-send-email-daniel.kiper@xxxxxxxxxx
[ Clarified the changelog. ]
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/x86/xen/efi.c |   45 ++++++++++++---------------------------------
 1 file changed, 12 insertions(+), 33 deletions(-)

--- a/arch/x86/xen/efi.c
+++ b/arch/x86/xen/efi.c
@@ -54,38 +54,6 @@ static efi_system_table_t efi_systab_xen
        .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_ef
 
        /* 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;



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