From: Borislav Petkov <b...@suse.de>
First, there was this: https://bugzilla.kernel.org/show_bug.cgi?id=88001
The problem there was that microcode patches are not being reapplied
after suspend-to-ram. It was important to reapply them, though, because
of for example Haswell's TSX erratum which disabled TSX instructions
with a microcode patch.
A simple fix was
fb86b97300d9 ("x86, microcode: Update BSPs microcode on resume")
but, as it is often the case, simple fixes are too simple. This one
causes 32-bit resume to fail:
https://bugzilla.kernel.org/show_bug.cgi?id=88391
Properly fixing this would require more involved changes for which it is
too late now, before the merge window. Thus, limit this to 64-bit only
temporarily.
Signed-off-by: Borislav Petkov <b...@suse.de>
---
arch/x86/kernel/cpu/microcode/core.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/x86/kernel/cpu/microcode/core.c
b/arch/x86/kernel/cpu/microcode/core.c
index 2ce9051174e6..08fe6e8a726e 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -465,6 +465,7 @@ static void mc_bp_resume(void)
if (uci->valid && uci->mc)
microcode_ops->apply_microcode(cpu);
+#ifdef CONFIG_X86_64
else if (!uci->mc)
/*
* We might resume and not have applied late microcode but still
@@ -473,6 +474,7 @@ static void mc_bp_resume(void)
* applying patches early on the APs.
*/
load_ucode_ap();
+#endif
}
static struct syscore_ops mc_syscore_ops = {
--
2.0.0
--
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