x86, microcode, AMD: Unify valid container checks

For additional coverage, BorisO and friends unknowlingly did swap AMD
microcode with Intel microcode blobs in order to see what happens. What
did happen on 32-bit was

[    5.722656] BUG: unable to handle kernel paging request at be3a6008
[    5.722693] IP: [<c106d6b4>] load_microcode_amd+0x24/0x3f0
[    5.722716] *pdpt = 0000000000000000 *pde = 0000000000000000

because there was a valid initrd there but without valid microcode in it
and the container check happened *after* the relocated ramdisk handling
on 32-bit, which was clearly wrong.

While at it, take care of the ramdisk relocation on both 32- and 64-bit
as it is done on both. Also, comment what we're doing because this code
is a bit tricky.

Reported-and-tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1391460104-7261-1-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 29 insertions, 14 deletions

diff --git a/arch/x86/kernel/cpu/microcode/amd_early.c b/arch/x86/kernel/cpu/microcode/amd_early.c
index 8384c0fa206f..617a9e284245 100644
--- a/arch/x86/kernel/cpu/microcode/amd_early.c
+++ b/arch/x86/kernel/cpu/microcode/amd_early.c
@@ -285,6 +285,15 @@ static void __init collect_cpu_sig_on_bsp(void *arg)
 
         uci->cpu_sig.sig = cpuid_eax(0x00000001);
 }
+
+static void __init get_bsp_sig(void)
+{
+        unsigned int bsp = boot_cpu_data.cpu_index;
+        struct ucode_cpu_info *uci = ucode_cpu_info + bsp;
+
+        if (!uci->cpu_sig.sig)
+                smp_call_function_single(bsp, collect_cpu_sig_on_bsp, NULL, 1);
+}
 #else
 void load_ucode_amd_ap(void)
 {
@@ -337,31 +346,37 @@ void load_ucode_amd_ap(void)
 
 int __init save_microcode_in_initrd_amd(void)
 {
+        unsigned long cont;
         enum ucode_state ret;
         u32 eax;
 
-#ifdef CONFIG_X86_32
-        unsigned int bsp = boot_cpu_data.cpu_index;
-        struct ucode_cpu_info *uci = ucode_cpu_info + bsp;
-
-        if (!uci->cpu_sig.sig)
-                smp_call_function_single(bsp, collect_cpu_sig_on_bsp, NULL, 1);
+        if (!container)
+                return -EINVAL;
 
+#ifdef CONFIG_X86_32
+        get_bsp_sig();
+        cont = (unsigned long)container;
+#else
         /*
-         * Take into account the fact that the ramdisk might get relocated
-         * and therefore we need to recompute the container's position in
-         * virtual memory space.
+         * We need the physical address of the container for both bitness since
+         * boot_params.hdr.ramdisk_image is a physical address.
          */
-        container = (u8 *)(__va((u32)relocated_ramdisk) +
-                           ((u32)container - boot_params.hdr.ramdisk_image));
+        cont = __pa(container);
 #endif
+
+        /*
+         * Take into account the fact that the ramdisk might get relocated and
+         * therefore we need to recompute the container's position in virtual
+         * memory space.
+         */
+        if (relocated_ramdisk)
+                container = (u8 *)(__va(relocated_ramdisk) +
+                             (cont - boot_params.hdr.ramdisk_image));
+
         if (ucode_new_rev)
                 pr_info("microcode: updated early to new patch_level=0x%08x\n",
                         ucode_new_rev);
 
-        if (!container)
-                return -EINVAL;
-
         eax   = cpuid_eax(0x00000001);
         eax   = ((eax >> 8) & 0xf) + ((eax >> 20) & 0xff);