6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
commit 5cc2db37124bb33914996d6fdbb2ddb3811f2945 upstream.
__static_call_update_early() has a check for early_boot_irqs_disabled, but
is used before early_boot_irqs_disabled is set up in start_kernel().
Xen PV has always special cased early_boot_irqs_disabled, but Xen PVH does
not and falls over the BUG when booting as dom0.
It is very suspect that early_boot_irqs_disabled starts as 0, becomes 1 for
a time, then becomes 0 again, but as this needs backporting to fix a
breakage in a security fix, dropping the BUG_ON() is the far safer option.
Fixes: 0ef8047b737d ("x86/static-call: provide a way to do very early static-call updates")
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219620
Reported-by: Alex Zenla <alex@xxxxxxxxx>
Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Tested-by: Alex Zenla <alex@xxxxxxxxx>
Link: https://lore.kernel.org/r/20241221211046.6475-1-andrew.cooper3@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/static_call.c | 1 -
1 file changed, 1 deletion(-)
--- a/arch/x86/kernel/static_call.c
+++ b/arch/x86/kernel/static_call.c
@@ -175,7 +175,6 @@ EXPORT_SYMBOL_GPL(arch_static_call_trans
noinstr void __static_call_update_early(void *tramp, void *func)
{
BUG_ON(system_state != SYSTEM_BOOTING);
- BUG_ON(!early_boot_irqs_disabled);
BUG_ON(static_call_initialized);
__text_gen_insn(tramp, JMP32_INSN_OPCODE, tramp, func, JMP32_INSN_SIZE);
sync_core();
