From nobody Sat Feb 7 15:16:02 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BEE80C433FE for ; Wed, 19 Oct 2022 10:17:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230016AbiJSKRi (ORCPT ); Wed, 19 Oct 2022 06:17:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34740 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230207AbiJSKQl (ORCPT ); Wed, 19 Oct 2022 06:16:41 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC0D410B787; Wed, 19 Oct 2022 02:57:38 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id E1A31CE2183; Wed, 19 Oct 2022 09:05:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C259AC433D6; Wed, 19 Oct 2022 09:05:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666170346; bh=QR0ElYQy4q9YU76kzPzxhsB29u2pO0wfg3SgVquJrmQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PTWlcAdbs2+3mf/yztbuU6JzEwarjj6pmA39ukFlsEZp2OC7I9rzxUOh0nt+dp3cq rP0iHMC3Bk/gISPkuJdPO/73zIjXgoEeYwq4FMG8ntW068G+rfvyaeVqQsazTwLzyz N7r+k+4jT6ED+2/D3IHnGdEbdYs6y8vfw+2rLx9w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nicholas Piggin , Michael Ellerman , Sasha Levin Subject: [PATCH 6.0 620/862] powerpc/64/interrupt: Fix return to masked context after hard-mask irq becomes pending Date: Wed, 19 Oct 2022 10:31:47 +0200 Message-Id: <20221019083317.332868643@linuxfoundation.org> X-Mailer: git-send-email 2.38.0 In-Reply-To: <20221019083249.951566199@linuxfoundation.org> References: <20221019083249.951566199@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Nicholas Piggin [ Upstream commit e485f6c751e0a969327336c635ca602feea117f0 ] If a synchronous interrupt (e.g., hash fault) is taken inside an irqs-disabled region which has MSR[EE]=3D1, then an asynchronous interrupt that is PACA_IRQ_MUST_HARD_MASK (e.g., PMI) is taken inside the synchronous interrupt handler, then the synchronous interrupt will return with MSR[EE]=3D1 and the asynchronous interrupt fires again. If the asynchronous interrupt is a PMI and the original context does not have PMIs disabled (only Linux IRQs), the asynchronous interrupt will fire despite having the PMI marked soft pending. This can confuse the perf code and cause warnings. This patch changes the interrupt return so that irqs-disabled MSR[EE]=3D1 contexts will be returned to with MSR[EE]=3D0 if a PACA_IRQ_MUST_HARD_MASK interrupt has become pending in the meantime. The longer explanation for what happens: 1. local_irq_disable() 2. Hash fault interrupt fires, do_hash_fault handler runs 3. interrupt_enter_prepare() sets IRQS_ALL_DISABLED 4. interrupt_enter_prepare() sets MSR[EE]=3D1 5. PMU interrupt fires, masked handler runs 6. Masked handler marks PMI pending 7. Masked handler returns with PACA_IRQ_HARD_DIS set, MSR[EE]=3D0 8. do_hash_fault interrupt return handler runs 9. interrupt_exit_kernel_prepare() clears PACA_IRQ_HARD_DIS 10. interrupt returns with MSR[EE]=3D1 11. PMU interrupt fires, perf handler runs Fixes: 4423eb5ae32e ("powerpc/64/interrupt: make normal synchronous interru= pts enable MSR[EE] if possible") Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220926054305.2671436-4-npiggin@gmail.com Signed-off-by: Sasha Levin --- arch/powerpc/kernel/interrupt.c | 10 --------- arch/powerpc/kernel/interrupt_64.S | 34 +++++++++++++++++++++++++++--- 2 files changed, 31 insertions(+), 13 deletions(-) diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrup= t.c index 0e75cb03244a..f9db0a172401 100644 --- a/arch/powerpc/kernel/interrupt.c +++ b/arch/powerpc/kernel/interrupt.c @@ -431,16 +431,6 @@ notrace unsigned long interrupt_exit_kernel_prepare(st= ruct pt_regs *regs) =20 if (unlikely(stack_store)) __hard_EE_RI_disable(); - /* - * Returning to a kernel context with local irqs disabled. - * Here, if EE was enabled in the interrupted context, enable - * it on return as well. A problem exists here where a soft - * masked interrupt may have cleared MSR[EE] and set HARD_DIS - * here, and it will still exist on return to the caller. This - * will be resolved by the masked interrupt firing again. - */ - if (regs->msr & MSR_EE) - local_paca->irq_happened &=3D ~PACA_IRQ_HARD_DIS; #endif /* CONFIG_PPC64 */ } =20 diff --git a/arch/powerpc/kernel/interrupt_64.S b/arch/powerpc/kernel/inter= rupt_64.S index ce25b28cf418..d76376ce7291 100644 --- a/arch/powerpc/kernel/interrupt_64.S +++ b/arch/powerpc/kernel/interrupt_64.S @@ -559,15 +559,43 @@ _ASM_NOKPROBE_SYMBOL(interrupt_return_\srr\()_kernel) ld r11,SOFTE(r1) cmpwi r11,IRQS_ENABLED stb r11,PACAIRQSOFTMASK(r13) - bne 1f + beq .Linterrupt_return_\srr\()_soft_enabled + + /* + * Returning to soft-disabled context. + * Check if a MUST_HARD_MASK interrupt has become pending, in which + * case we need to disable MSR[EE] in the return context. + */ + ld r12,_MSR(r1) + andi. r10,r12,MSR_EE + beq .Lfast_kernel_interrupt_return_\srr\() // EE already disabled + lbz r11,PACAIRQHAPPENED(r13) + andi. r10,r11,PACA_IRQ_MUST_HARD_MASK + beq 1f // No HARD_MASK pending + + /* Must clear MSR_EE from _MSR */ +#ifdef CONFIG_PPC_BOOK3S + li r10,0 + /* Clear valid before changing _MSR */ + .ifc \srr,srr + stb r10,PACASRR_VALID(r13) + .else + stb r10,PACAHSRR_VALID(r13) + .endif +#endif + xori r12,r12,MSR_EE + std r12,_MSR(r1) + b .Lfast_kernel_interrupt_return_\srr\() + +.Linterrupt_return_\srr\()_soft_enabled: #ifdef CONFIG_PPC_BOOK3S lbz r11,PACAIRQHAPPENED(r13) andi. r11,r11,(~PACA_IRQ_HARD_DIS)@l bne- interrupt_return_\srr\()_kernel_restart #endif - li r11,0 - stb r11,PACAIRQHAPPENED(r13) # clear out possible HARD_DIS 1: + li r11,0 + stb r11,PACAIRQHAPPENED(r13) // clear the possible HARD_DIS =20 .Lfast_kernel_interrupt_return_\srr\(): cmpdi cr1,r3,0 --=20 2.35.1