From: Julien Grall <julien.grall@arm.com>
To: "Marc Zyngier" <marc.zyngier@arm.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>
Cc: kvm@vger.kernel.org,
Richard Henderson <richard.henderson@linaro.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 05/11] KVM: arm/arm64: Reset the VCPU without preemption and vcpu state loaded
Date: Mon, 4 Mar 2019 17:31:22 +0000 [thread overview]
Message-ID: <0325e384-7677-8757-dfc3-4f20eb11442f@arm.com> (raw)
In-Reply-To: <ec205905-6b7b-2a6d-f70f-9bca574dd593@arm.com>
Hi,
On 04/03/2019 17:06, Marc Zyngier wrote:
> On 04/03/2019 16:30, Julien Grall wrote:
>> Hi,
>>
>> I noticed some issues with this patch when rebooting a guest after using perf.
>>
>> [ 577.513447] BUG: sleeping function called from invalid context at
>> kernel/locking/mutex.c:908
>> [ 577.521926] in_atomic(): 1, irqs_disabled(): 0, pid: 2323, name: qemu-system aar
>> [ 577.529354] 1 lock held by qemu-system-aar/2323:
>> [ 577.533998] #0: 00000000f4f96804 (&vcpu->mutex){+.+.}, at:
>> kvm_vcpu_ioctl+0x74/0xac0
>> [ 577.541865] Preemption disabled at:
>> [ 577.541871] [<ffff0000100cc82c>] kvm_reset_vcpu+0x1c/0x1d0
>> [ 577.550882] CPU: 6 PID: 2323 Comm: qemu-system-aar Tainted: G W 5.0.0
>> #1277
>> [ 577.559137] Hardware name: AMD Seattle (Rev.B0) Development Board (Overdrive)
>> (DT)
>> [ 577.566698] Call trace:
>> [ 577.569138] dump_backtrace+0x0/0x140
>> [ 577.572793] show_stack+0x14/0x20
>> [ 577.576103] dump_stack+0xa0/0xd4
>> [ 577.579412] ___might_sleep+0x1e4/0x2b0
>> [ 577.583241] __might_sleep+0x60/0xb8
>> [ 577.586810] __mutex_lock+0x58/0x860
>> [ 577.590378] mutex_lock_nested+0x1c/0x28
>> [ 577.594294] perf_event_ctx_lock_nested+0xf4/0x238
>> [ 577.599078] perf_event_read_value+0x24/0x60
>> [ 577.603341] kvm_pmu_get_counter_value+0x80/0xe8
>> [ 577.607950] kvm_pmu_stop_counter+0x2c/0x98
>> [ 577.612126] kvm_pmu_vcpu_reset+0x58/0xd0
>> [ 577.616128] kvm_reset_vcpu+0xec/0x1d0
>> [ 577.619869] kvm_arch_vcpu_ioctl+0x6b0/0x860
>> [ 577.624131] kvm_vcpu_ioctl+0xe0/0xac0
>> [ 577.627876] do_vfs_ioctl+0xbc/0x910
>> [ 577.631443] ksys_ioctl+0x78/0xa8
>> [ 577.634751] __arm64_sys_ioctl+0x1c/0x28
>> [ 577.638667] el0_svc_common+0x90/0x118
>> [ 577.642408] el0_svc_handler+0x2c/0x80
>> [ 577.646150] el0_svc+0x8/0xc
>>
>> This is happening because the vCPU reset code is now running with preemption
>> disable. However, the perf code cannot be called with preemption disabled as it
>> is using mutex.
>>
>> Do you have any suggestion on the way to fix this potential issue?
>
> Given that the PMU is entirely emulated, it never has any state loaded
> on the CPU. It thus doesn't need to be part of the non-preemptible section.
>
> Can you please give this (untested) patchlet one a go? It's not exactly
> pretty, but I believe it will do the trick.
It does the trick. Are you going to submit the patch?
Cheers,
--
Julien Grall
next prev parent reply other threads:[~2019-03-04 17:31 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-07 13:18 [GIT PULL] KVM/ARM updates for 5.0-rc6 Marc Zyngier
2019-02-07 13:18 ` [PATCH 01/11] KVM: arm/arm64: vgic: Make vgic_irq->irq_lock a raw_spinlock Marc Zyngier
2019-02-07 13:18 ` [PATCH 02/11] KVM: arm/arm64: vgic: Make vgic_dist->lpi_list_lock " Marc Zyngier
2019-02-07 13:18 ` [PATCH 03/11] KVM: arm/arm64: vgic: Make vgic_cpu->ap_list_lock " Marc Zyngier
2019-02-07 13:18 ` [PATCH 04/11] arm64: KVM: Don't generate UNDEF when LORegion feature is present Marc Zyngier
2019-02-07 13:18 ` [PATCH 05/11] KVM: arm/arm64: Reset the VCPU without preemption and vcpu state loaded Marc Zyngier
2019-03-04 16:30 ` Julien Grall
2019-03-04 17:06 ` Marc Zyngier
2019-03-04 17:31 ` Julien Grall [this message]
2019-03-04 17:37 ` Marc Zyngier
2019-02-07 13:18 ` [PATCH 06/11] arm/arm64: KVM: Allow a VCPU to fully reset itself Marc Zyngier
2019-02-07 13:18 ` [PATCH 07/11] arm/arm64: KVM: Don't panic on failure to properly reset system registers Marc Zyngier
2019-02-07 13:18 ` [PATCH 08/11] KVM: arm/arm64: vgic: Always initialize the group of private IRQs Marc Zyngier
2019-02-07 13:18 ` [PATCH 09/11] arm: KVM: Add missing kvm_stage2_has_pmd() helper Marc Zyngier
2019-02-07 13:18 ` [PATCH 10/11] KVM: arm64: Relax the restriction on using stage2 PUD huge mapping Marc Zyngier
2019-02-07 13:18 ` [PATCH 11/11] KVM: arm64: Forbid kprobing of the VHE world-switch code Marc Zyngier
2019-02-13 18:39 ` [GIT PULL] KVM/ARM updates for 5.0-rc6 Paolo Bonzini
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