6.6-stable review patch. If anyone has any objections, please let me know.
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From: Andrew Cooper andrew.cooper3@citrix.com
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@edera.dev Suggested-by: Peter Zijlstra peterz@infradead.org Signed-off-by: Andrew Cooper andrew.cooper3@citrix.com Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Reviewed-by: Juergen Gross jgross@suse.com Acked-by: Peter Zijlstra (Intel) peterz@infradead.org Tested-by: Alex Zenla alex@edera.dev Link: https://lore.kernel.org/r/20241221211046.6475-1-andrew.cooper3@citrix.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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();