From mboxrd@z Thu Jan 1 00:00:00 1970 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 B4718CDB474 for ; Tue, 17 Oct 2023 21:49:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344124AbjJQVth (ORCPT ); Tue, 17 Oct 2023 17:49:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54076 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230056AbjJQVtf (ORCPT ); Tue, 17 Oct 2023 17:49:35 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D995EB0 for ; Tue, 17 Oct 2023 14:49:33 -0700 (PDT) Message-ID: <20231017211723.968077065@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1697579372; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=upCMQ/5CIR2zAhmP8hpPxpV8M1jyj+Jpzo+XS/jhO+0=; b=1PnSod6vZzDr9jJkGLsmQyMOGlxpyZVl325FufYwCF48Xw+wAgYWx9erUjmqms9yvST0sN KXyzLp4Ero8ZBtP9Gd33QYnedGX20/+CfN/HkPszzJ1mVsMCGd8a44Jfu+D7Tg3pdRqmk2 XxHeqONERElAlL31lC5cgBUcnKBWswAhk/ThxGBr+sugzm7uzI/Gkj8DE0y9JZUXMBQxZJ V5Jpx2QjnUSn7gF0fmdGsP0hIfelaX3MPsFNadzJ7T7Zo5QQYDU+Xp3nyl8J3oG+fT0JYT lcihwE8oqgaBhvRZYE+nMWD8VjwSN00MJZ47waqRDb9btSCWXdRZAdkERKO2uA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1697579372; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=upCMQ/5CIR2zAhmP8hpPxpV8M1jyj+Jpzo+XS/jhO+0=; b=SxAZKWhlYrQ2qxhOmlrf/Q5QqX8qsd/s9oTnpL6P42nkGhcv4nm1Q7girkdq3YhV4aNzcW ptj/64LlUFzwrGAQ== From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Borislav Petkov Subject: [patch V5 36/39] x86/apic: Provide apic_force_nmi_on_cpu() References: <20231017200758.877560658@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Date: Tue, 17 Oct 2023 23:24:13 +0200 (CEST) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner When SMT siblings are soft-offlined and parked in one of the play_dead() variants they still react on NMI, which is problematic on affected Intel CPUs. The default play_dead() variant uses MWAIT on modern CPUs, which is not guaranteed to be safe when updated concurrently. Right now late loading is prevented when not all SMT siblings are online, but as they still react on NMI, it is possible to bring them out of their park position into a trivial rendezvous handler. Provide a function which allows to do that. I does sanity checks whether the target is in the cpus_booted_once_mask and whether the APIC driver supports it. Mark X2APIC and XAPIC as capable, but exclude 32bit and the UV and NUMACHIP variants as that needs feedback from the relevant experts. Signed-off-by: Thomas Gleixner --- arch/x86/include/asm/apic.h | 5 ++++- arch/x86/kernel/apic/apic_flat_64.c | 2 ++ arch/x86/kernel/apic/ipi.c | 8 ++++++++ arch/x86/kernel/apic/x2apic_cluster.c | 1 + arch/x86/kernel/apic/x2apic_phys.c | 1 + 5 files changed, 16 insertions(+), 1 deletion(-) --- --- a/arch/x86/include/asm/apic.h +++ b/arch/x86/include/asm/apic.h @@ -276,7 +276,8 @@ struct apic { u32 disable_esr : 1, dest_mode_logical : 1, - x2apic_set_max_apicid : 1; + x2apic_set_max_apicid : 1, + nmi_to_offline_cpu : 1; u32 (*calc_dest_apicid)(unsigned int cpu); @@ -542,6 +543,8 @@ extern bool default_check_apicid_used(ph extern void default_ioapic_phys_id_map(physid_mask_t *phys_map, physid_mask_t *retmap); extern int default_cpu_present_to_apicid(int mps_cpu); +void apic_send_nmi_to_offline_cpu(unsigned int cpu); + #else /* CONFIG_X86_LOCAL_APIC */ static inline unsigned int read_apic_id(void) { return 0; } --- a/arch/x86/kernel/apic/apic_flat_64.c +++ b/arch/x86/kernel/apic/apic_flat_64.c @@ -103,6 +103,7 @@ static struct apic apic_flat __ro_after_ .send_IPI_allbutself = default_send_IPI_allbutself, .send_IPI_all = default_send_IPI_all, .send_IPI_self = default_send_IPI_self, + .nmi_to_offline_cpu = true, .read = native_apic_mem_read, .write = native_apic_mem_write, @@ -175,6 +176,7 @@ static struct apic apic_physflat __ro_af .send_IPI_allbutself = default_send_IPI_allbutself, .send_IPI_all = default_send_IPI_all, .send_IPI_self = default_send_IPI_self, + .nmi_to_offline_cpu = true, .read = native_apic_mem_read, .write = native_apic_mem_write, --- a/arch/x86/kernel/apic/ipi.c +++ b/arch/x86/kernel/apic/ipi.c @@ -97,6 +97,14 @@ void native_send_call_func_ipi(const str __apic_send_IPI_mask(mask, CALL_FUNCTION_VECTOR); } +void apic_send_nmi_to_offline_cpu(unsigned int cpu) +{ + if (WARN_ON_ONCE(!apic->nmi_to_offline_cpu)) + return; + if (WARN_ON_ONCE(!cpumask_test_cpu(cpu, &cpus_booted_once_mask))) + return; + apic->send_IPI(cpu, NMI_VECTOR); +} #endif /* CONFIG_SMP */ static inline int __prepare_ICR2(unsigned int mask) --- a/arch/x86/kernel/apic/x2apic_cluster.c +++ b/arch/x86/kernel/apic/x2apic_cluster.c @@ -251,6 +251,7 @@ static struct apic apic_x2apic_cluster _ .send_IPI_allbutself = x2apic_send_IPI_allbutself, .send_IPI_all = x2apic_send_IPI_all, .send_IPI_self = x2apic_send_IPI_self, + .nmi_to_offline_cpu = true, .read = native_apic_msr_read, .write = native_apic_msr_write, --- a/arch/x86/kernel/apic/x2apic_phys.c +++ b/arch/x86/kernel/apic/x2apic_phys.c @@ -166,6 +166,7 @@ static struct apic apic_x2apic_phys __ro .send_IPI_allbutself = x2apic_send_IPI_allbutself, .send_IPI_all = x2apic_send_IPI_all, .send_IPI_self = x2apic_send_IPI_self, + .nmi_to_offline_cpu = true, .read = native_apic_msr_read, .write = native_apic_msr_write,