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Date:   Tue, 11 Jan 2022 09:13:17 -0300
From:   Marcelo Tosatti <mtosatti@redhat.com>
To:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] KVM: VMX: switch wakeup_vcpus_on_cpu_lock to raw spinlock
Message-ID: <20220111121317.GA8480@fuller.cnet>
References: <20220107175114.GA261406@fuller.cnet>
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On Tue, Jan 11, 2022 at 12:36:35PM +0100, Sebastian Andrzej Siewior wrote:
> On 2022-01-07 14:51:14 [-0300], Marcelo Tosatti wrote:
> > 
> > wakeup_vcpus_on_cpu_lock is taken from hard interrupt context 
> > (pi_wakeup_handler), therefore it cannot sleep.
> > 
> > Switch it to a raw spinlock.
> > 
> > Fixes:
> > 
> > [41297.066254] BUG: scheduling while atomic: CPU 0/KVM/635218/0x00010001 
> > [41297.066323] Preemption disabled at: 
> > [41297.066324] [<ffffffff902ee47f>] irq_enter_rcu+0xf/0x60 
> > [41297.066339] Call Trace: 
> > [41297.066342]  <IRQ> 
> > [41297.066346]  dump_stack_lvl+0x34/0x44 
> > [41297.066353]  ? irq_enter_rcu+0xf/0x60 
> > [41297.066356]  __schedule_bug.cold+0x7d/0x8b 
> > [41297.066361]  __schedule+0x439/0x5b0 
> > [41297.066365]  ? task_blocks_on_rt_mutex.constprop.0.isra.0+0x1b0/0x440 
> > [41297.066369]  schedule_rtlock+0x1e/0x40 
> > [41297.066371]  rtlock_slowlock_locked+0xf1/0x260 
> > [41297.066374]  rt_spin_lock+0x3b/0x60 
> > [41297.066378]  pi_wakeup_handler+0x31/0x90 [kvm_intel] 
> > [41297.066388]  sysvec_kvm_posted_intr_wakeup_ipi+0x9d/0xd0 
> > [41297.066392]  </IRQ> 
> > [41297.066392]  asm_sysvec_kvm_posted_intr_wakeup_ipi+0x12/0x20 
> > ...
> > 
> > Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
> 
> so I have here v5.16 and no wakeup_vcpus_on_cpu_lock. It was also not
> removed so this patch is not intended for a previous kernel. Also
> checked next-20220111 and no wakeup_vcpus_on_cpu_lock.
> 
> Sebastian
> 
> 

Sebastian,

The variable has been renamed on kvm.git/queue (sorry for not mentioning
that).

I suppose Paolo can integrate through kvm.git.