[PATCH] x86/MTRR: hook mtrr_bp_restore() back up

[Jan Beulich <jbeulich@xxxxxxxx>]

Unlike stated in the offending commit's description,
load_system_tables() wasn't the only thing left to retain from the
earlier restore_rest_processor_state().

While there also do Misra-related tidying for the function itself: The
function being used from assembly only means it doesn't need to have a
declaration, but wants to be asmlinkage.

Fixes: 4304ff420e51 ("x86/S3: Drop {save,restore}_rest_processor_state() 
completely")
Reported-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Contextually assumed to go on top of "x86/MTRR: constrain AP sync and
BSP restore". Functionally there's no dependency.

--- a/xen/arch/x86/acpi/wakeup_prot.S
+++ b/xen/arch/x86/acpi/wakeup_prot.S
@@ -124,6 +124,8 @@ LABEL(s3_resume)
         mov     STACK_CPUINFO_FIELD(cr4)(%rbx), %rax
         mov     %rax, %cr4
 
+        call    mtrr_bp_restore
+
 .Lsuspend_err:
         pop     %r15
         pop     %r14
--- a/xen/arch/x86/cpu/mtrr/main.c
+++ b/xen/arch/x86/cpu/mtrr/main.c
@@ -610,7 +610,7 @@ void mtrr_aps_sync_end(void)
        hold_mtrr_updates_on_aps = 0;
 }
 
-void mtrr_bp_restore(void)
+void asmlinkage mtrr_bp_restore(void)
 {
        if (mtrr_if)
                mtrr_set_all();
--- a/xen/arch/x86/include/asm/mtrr.h
+++ b/xen/arch/x86/include/asm/mtrr.h
@@ -66,7 +66,6 @@ extern uint8_t pat_type_2_pte_flags(uint
 extern int hold_mtrr_updates_on_aps;
 extern void mtrr_aps_sync_begin(void);
 extern void mtrr_aps_sync_end(void);
-extern void mtrr_bp_restore(void);
 
 extern bool mtrr_var_range_msr_set(struct domain *d, struct mtrr_state *m,
                                    uint32_t msr, uint64_t msr_content);