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Violators will be prosecuted; Mon, 15 Feb 2016 11:56:22 +1000 X-IBM-Helo: d23dlp02.au.ibm.com X-IBM-MailFrom: aik@ozlabs.ru X-IBM-RcptTo: kvm-ppc@vger.kernel.org;kvm@vger.kernel.org Received: from d23relay09.au.ibm.com (d23relay09.au.ibm.com [9.185.63.181]) by d23dlp02.au.ibm.com (Postfix) with ESMTP id E8D942BB0057; Mon, 15 Feb 2016 12:56:21 +1100 (EST) Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139]) by d23relay09.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u1F1u6bY52887584; Mon, 15 Feb 2016 12:56:21 +1100 Received: from d23av04.au.ibm.com (localhost [127.0.0.1]) by d23av04.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u1F1tgof006491; Mon, 15 Feb 2016 12:55:42 +1100 Received: from ozlabs.au.ibm.com (ozlabs.au.ibm.com [9.192.253.14]) by d23av04.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id u1F1tgs9005839; Mon, 15 Feb 2016 12:55:42 +1100 Received: from bran.ozlabs.ibm.com (haven.au.ibm.com [9.192.254.114]) by ozlabs.au.ibm.com (Postfix) with ESMTP id E2B58A0279; Mon, 15 Feb 2016 12:55:17 +1100 (AEDT) Received: from vpl2.ozlabs.ibm.com (vpl2.ozlabs.ibm.com [10.61.141.27]) by bran.ozlabs.ibm.com (Postfix) with ESMTP id D98A2E39B9; Mon, 15 Feb 2016 12:55:17 +1100 (AEDT) From: Alexey Kardashevskiy To: linuxppc-dev@lists.ozlabs.org Cc: Alexey Kardashevskiy , Alexander Graf , Paul Mackerras , kvm-ppc@vger.kernel.org, kvm@vger.kernel.org Subject: [PATCH kernel v3 3/7] KVM: PPC: Use RCU for arch.spapr_tce_tables Date: Mon, 15 Feb 2016 12:55:05 +1100 Message-Id: <1455501309-47200-4-git-send-email-aik@ozlabs.ru> X-Mailer: git-send-email 2.5.0.rc3 In-Reply-To: <1455501309-47200-1-git-send-email-aik@ozlabs.ru> References: <1455501309-47200-1-git-send-email-aik@ozlabs.ru> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16021501-0017-0000-0000-000002CB3726 Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org At the moment only spapr_tce_tables updates are protected against races but not lookups. This fixes missing protection by using RCU for the list. As lookups also happen in real mode, this uses list_for_each_entry_lockless() (which is expected not to access any vmalloc'd memory). This converts release_spapr_tce_table() to a RCU scheduled handler. Signed-off-by: Alexey Kardashevskiy Reviewed-by: David Gibson --- Changes: v3: * moved list_for_each_entry_lockless() from the previous patch here * clarified in the commit what is and what is not protected against races --- arch/powerpc/include/asm/kvm_host.h | 1 + arch/powerpc/kvm/book3s.c | 2 +- arch/powerpc/kvm/book3s_64_vio.c | 20 +++++++++++--------- arch/powerpc/kvm/book3s_64_vio_hv.c | 2 +- 4 files changed, 14 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index 9d08d8c..ffdbc2d 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -183,6 +183,7 @@ struct kvmppc_spapr_tce_table { struct kvm *kvm; u64 liobn; u32 window_size; + struct rcu_head rcu; struct page *pages[0]; }; diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c index 638c6d9..b34220d 100644 --- a/arch/powerpc/kvm/book3s.c +++ b/arch/powerpc/kvm/book3s.c @@ -807,7 +807,7 @@ int kvmppc_core_init_vm(struct kvm *kvm) { #ifdef CONFIG_PPC64 - INIT_LIST_HEAD(&kvm->arch.spapr_tce_tables); + INIT_LIST_HEAD_RCU(&kvm->arch.spapr_tce_tables); INIT_LIST_HEAD(&kvm->arch.rtas_tokens); #endif diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c index 54cf9bc..9526c34 100644 --- a/arch/powerpc/kvm/book3s_64_vio.c +++ b/arch/powerpc/kvm/book3s_64_vio.c @@ -45,19 +45,16 @@ static long kvmppc_stt_npages(unsigned long window_size) * sizeof(u64), PAGE_SIZE) / PAGE_SIZE; } -static void release_spapr_tce_table(struct kvmppc_spapr_tce_table *stt) +static void release_spapr_tce_table(struct rcu_head *head) { - struct kvm *kvm = stt->kvm; + struct kvmppc_spapr_tce_table *stt = container_of(head, + struct kvmppc_spapr_tce_table, rcu); int i; - mutex_lock(&kvm->lock); - list_del(&stt->list); for (i = 0; i < kvmppc_stt_npages(stt->window_size); i++) __free_page(stt->pages[i]); + kfree(stt); - mutex_unlock(&kvm->lock); - - kvm_put_kvm(kvm); } static int kvm_spapr_tce_fault(struct vm_area_struct *vma, struct vm_fault *vmf) @@ -88,7 +85,12 @@ static int kvm_spapr_tce_release(struct inode *inode, struct file *filp) { struct kvmppc_spapr_tce_table *stt = filp->private_data; - release_spapr_tce_table(stt); + list_del_rcu(&stt->list); + + kvm_put_kvm(stt->kvm); + + call_rcu(&stt->rcu, release_spapr_tce_table); + return 0; } @@ -131,7 +133,7 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, kvm_get_kvm(kvm); mutex_lock(&kvm->lock); - list_add(&stt->list, &kvm->arch.spapr_tce_tables); + list_add_rcu(&stt->list, &kvm->arch.spapr_tce_tables); mutex_unlock(&kvm->lock); diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c index f29ba2c..124d692 100644 --- a/arch/powerpc/kvm/book3s_64_vio_hv.c +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c @@ -51,7 +51,7 @@ static struct kvmppc_spapr_tce_table *kvmppc_find_table(struct kvm_vcpu *vcpu, struct kvm *kvm = vcpu->kvm; struct kvmppc_spapr_tce_table *stt; - list_for_each_entry(stt, &kvm->arch.spapr_tce_tables, list) + list_for_each_entry_lockless(stt, &kvm->arch.spapr_tce_tables, list) if (stt->liobn == liobn) return stt;