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[98.239.145.235]) by smtp.gmail.com with ESMTPSA id b3sm2002837qte.85.2020.11.05.16.35.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Nov 2020 16:35:42 -0800 (PST) From: Brian Masney To: boris.ostrovsky@oracle.com, jgross@suse.com, sstabellini@kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, dustymabe@redhat.com Subject: [PATCH] x86/xen: fix warning when running with nosmt mitigations Date: Thu, 5 Nov 2020 19:35:29 -0500 Message-Id: <20201106003529.391649-1-bmasney@redhat.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When booting a hyperthreaded system with the kernel parameter 'mitigations=auto,nosmt', the following warning occurs: WARNING: CPU: 0 PID: 1 at drivers/xen/events/events_base.c:1112 unbind_from_irqhandler+0x4e/0x60 ... Hardware name: Xen HVM domU, BIOS 4.2.amazon 08/24/2006 ... Call Trace: xen_uninit_lock_cpu+0x28/0x62 xen_hvm_cpu_die+0x21/0x30 takedown_cpu+0x9c/0xe0 ? trace_suspend_resume+0x60/0x60 cpuhp_invoke_callback+0x9a/0x530 _cpu_up+0x11a/0x130 cpu_up+0x7e/0xc0 bringup_nonboot_cpus+0x48/0x50 smp_init+0x26/0x79 kernel_init_freeable+0xea/0x229 ? rest_init+0xaa/0xaa kernel_init+0xa/0x106 ret_from_fork+0x35/0x40 The secondary CPUs are not activated with the nosmt mitigations and only the primary thread on each CPU core is used. In this situation, xen_hvm_smp_prepare_cpus(), and more importantly xen_init_lock_cpu(), is not called, so the lock_kicker_irq is not initialized for the secondary CPUs. Let's fix this by exiting early in xen_uninit_lock_cpu() if the irq is not set to avoid the warning from above for each secondary CPU. Signed-off-by: Brian Masney --- arch/x86/xen/spinlock.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c index 799f4eba0a62..4a052459a08e 100644 --- a/arch/x86/xen/spinlock.c +++ b/arch/x86/xen/spinlock.c @@ -93,9 +93,24 @@ void xen_init_lock_cpu(int cpu) void xen_uninit_lock_cpu(int cpu) { + int irq; + if (!xen_pvspin) return; + /* + * When booting the kernel with 'mitigations=auto,nosmt', the secondary + * CPUs are not activated and only the primary thread on each CPU core + * is used. In this situation, xen_hvm_smp_prepare_cpus(), and more + * importantly xen_init_lock_cpu(), is not called, so the + * lock_kicker_irq is not initialized for the secondary CPUs. Let's + * exit early if the irq is not set to avoid a warning in the console + * log. + */ + irq = per_cpu(lock_kicker_irq, cpu); + if (irq == -1) + return; + unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL); per_cpu(lock_kicker_irq, cpu) = -1; kfree(per_cpu(irq_name, cpu)); -- 2.26.2