x86/microcode/AMD: Reload proper initrd start address

When we switch to virtual addresses and, especially after
reserve_initrd()->relocate_initrd() have run, we have the updated initrd
address in initrd_start. Use initrd_start then instead of the address
which has been passed to us through boot params. (That still gets used
when we're running the very early routines on the BSP).

Reported-and-tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/20161220144012.lc4cwrg6dphqbyqu@pd.tnic
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index c4bb2f7169f634901bddab79f219021b0219c049..2af69d27da629a5c802498e692300f9980862a2a 100644 (file)
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -243,14 +243,12 @@ struct cpio_data find_microcode_in_initrd(const char *path, bool use_pa)
 # endif
 
        /*
-        * Did we relocate the ramdisk?
-        *
-        * So we possibly relocate the ramdisk *after* applying microcode on the
-        * BSP so we rely on use_pa (use physical addresses) - even if it is not
-        * absolutely correct - to determine whether we've done the ramdisk
-        * relocation already.
+        * Fixup the start address: after reserve_initrd() runs, initrd_start
+        * has the virtual address of the beginning of the initrd. It also
+        * possibly relocates the ramdisk. In either case, initrd_start contains
+        * the updated address so use that instead.
         */
-       if (!use_pa && relocated_ramdisk)
+       if (!use_pa && initrd_start)
                start = initrd_start;
 
        return find_cpio_data(path, (void *)start, size, NULL);