From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756035AbcIFJwG convert rfc822-to-8bit (ORCPT ); Tue, 6 Sep 2016 05:52:06 -0400 Received: from fw-tnat.cambridge.arm.com ([217.140.96.140]:54234 "EHLO cam-smtp0.cambridge.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755317AbcIFJwE (ORCPT ); Tue, 6 Sep 2016 05:52:04 -0400 From: Punit Agrawal To: Christoffer Dall Cc: kvm@vger.kernel.org, Marc Zyngier , Will Deacon , linux-kernel@vger.kernel.org, Steven Rostedt , Ingo Molnar , Paolo Bonzini , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Subject: Re: [RFC v2 PATCH 2/7] KVM: Track the pid of the VM process References: <1473093097-30932-1-git-send-email-punit.agrawal@arm.com> <1473093097-30932-3-git-send-email-punit.agrawal@arm.com> <20160906062252.GA30513@cbox> Date: Tue, 06 Sep 2016 10:51:27 +0100 In-Reply-To: <20160906062252.GA30513@cbox> (Christoffer Dall's message of "Tue, 6 Sep 2016 08:22:52 +0200") Message-ID: <87poohjqzk.fsf@e105922-lin.cambridge.arm.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Christoffer, Christoffer Dall writes: > On Mon, Sep 05, 2016 at 05:31:32PM +0100, Punit Agrawal wrote: >> Userspace tools such as perf can be used to profile individual >> processes. >> >> Track the PID of the virtual machine process to match profiling requests >> targeted at it. This can be used to take appropriate action to enable >> the requested profiling operations for the VMs of interest. >> >> Signed-off-by: Punit Agrawal >> Cc: Paolo Bonzini >> Cc: "Radim Krčmář" >> Cc: Christoffer Dall >> Cc: Marc Zyngier >> --- >> include/linux/kvm_host.h | 1 + >> virt/kvm/kvm_main.c | 2 ++ >> 2 files changed, 3 insertions(+) >> >> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h >> index 9c28b4d..7c42c94 100644 >> --- a/include/linux/kvm_host.h >> +++ b/include/linux/kvm_host.h >> @@ -374,6 +374,7 @@ struct kvm_memslots { >> struct kvm { >> spinlock_t mmu_lock; >> struct mutex slots_lock; >> + struct pid *pid; >> struct mm_struct *mm; /* userspace tied to this vm */ >> struct kvm_memslots *memslots[KVM_ADDRESS_SPACE_NUM]; >> struct srcu_struct srcu; >> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c >> index 1950782..ab2535a 100644 >> --- a/virt/kvm/kvm_main.c >> +++ b/virt/kvm/kvm_main.c >> @@ -613,6 +613,7 @@ static struct kvm *kvm_create_vm(unsigned long type) >> spin_lock_init(&kvm->mmu_lock); >> atomic_inc(¤t->mm->mm_count); >> kvm->mm = current->mm; >> + kvm->pid = get_task_pid(current, PIDTYPE_PID); > > How dooes this deal with threading? Is the idea that the user by > specifying the main thread's pid will enable trapping for all vcpu > threads belonging to that VM? Yes that's correct - specifying the main thread PID will enable trapping for the VM (all vcpus). I am happy to move to a more suitable identifier if available. Thanks, Punit > >> kvm_eventfd_init(kvm); >> mutex_init(&kvm->lock); >> mutex_init(&kvm->irq_lock); >> @@ -712,6 +713,7 @@ static void kvm_destroy_vm(struct kvm *kvm) >> int i; >> struct mm_struct *mm = kvm->mm; >> >> + put_pid(kvm->pid); >> kvm_destroy_vm_debugfs(kvm); >> kvm_arch_sync_events(kvm); >> spin_lock(&kvm_lock); >> -- >> 2.8.1 >> > _______________________________________________ > kvmarm mailing list > kvmarm@lists.cs.columbia.edu > https://lists.cs.columbia.edu/mailman/listinfo/kvmarm