From patchwork Fri Sep 7 06:14:20 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiao Guangrong X-Patchwork-Id: 1419931 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork1.kernel.org (Postfix) with ESMTP id 807A63FC85 for ; Fri, 7 Sep 2012 06:14:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932897Ab2IGGO3 (ORCPT ); Fri, 7 Sep 2012 02:14:29 -0400 Received: from e23smtp03.au.ibm.com ([202.81.31.145]:55778 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932704Ab2IGGO1 (ORCPT ); Fri, 7 Sep 2012 02:14:27 -0400 Received: from /spool/local by e23smtp03.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Fri, 7 Sep 2012 16:13:00 +1000 Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay04.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q8765L1A30539912; Fri, 7 Sep 2012 16:05:22 +1000 Received: from d23av01.au.ibm.com (loopback [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q876EMZ9006173; Fri, 7 Sep 2012 16:14:22 +1000 Received: from localhost.localdomain ([9.123.236.99]) by d23av01.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id q876EKY4005705; Fri, 7 Sep 2012 16:14:20 +1000 Message-ID: <504990BC.3010703@linux.vnet.ibm.com> Date: Fri, 07 Sep 2012 14:14:20 +0800 From: Xiao Guangrong User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120827 Thunderbird/15.0 MIME-Version: 1.0 To: Xiao Guangrong CC: Avi Kivity , Marcelo Tosatti , LKML , KVM Subject: [PATCH 2/3] KVM: fix release error page References: <5049908A.7070501@linux.vnet.ibm.com> In-Reply-To: <5049908A.7070501@linux.vnet.ibm.com> x-cbid: 12090706-6102-0000-0000-000002311254 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org This bug was triggered: [ 4220.198458] BUG: unable to handle kernel paging request at fffffffffffffffe [ 4220.203907] IP: [] put_page+0xf/0x34 ...... [ 4220.237326] Call Trace: [ 4220.237361] [] kvm_arch_destroy_vm+0xf9/0x101 [kvm] [ 4220.237382] [] kvm_put_kvm+0xcc/0x127 [kvm] [ 4220.237401] [] kvm_vcpu_release+0x18/0x1c [kvm] [ 4220.237407] [] __fput+0x111/0x1ed [ 4220.237411] [] ____fput+0xe/0x10 [ 4220.237418] [] task_work_run+0x5d/0x88 [ 4220.237424] [] do_exit+0x2bf/0x7ca The test case: #include #include #include #include #include #include #include #include #include #include #define die(fmt, args...) do { \ printf(fmt, ##args); \ exit(-1);} while (0) static int create_vm(void) { int sys_fd, vm_fd; sys_fd = open("/dev/kvm", O_RDWR); if (sys_fd < 0) die("open /dev/kvm fail.\n"); vm_fd = ioctl(sys_fd, KVM_CREATE_VM, 0); if (vm_fd < 0) die("KVM_CREATE_VM fail.\n"); return vm_fd; } static int create_vcpu(int vm_fd) { int vcpu_fd; vcpu_fd = ioctl(vm_fd, KVM_CREATE_VCPU, 0); if (vcpu_fd < 0) die("KVM_CREATE_VCPU ioctl.\n"); printf("Create vcpu.\n"); return vcpu_fd; } static void *vcpu_thread(void *arg) { int vm_fd = (int)(long)arg; create_vcpu(vm_fd); return NULL; } int main(int argc, char *argv[]) { pthread_t thread; int vm_fd; (void)argc; (void)argv; vm_fd = create_vm(); pthread_create(&thread, NULL, vcpu_thread, (void *)(long)vm_fd); printf("Exit.\n"); return 0; } It caused by release kvm->arch.ept_identity_map_addr which is the error page. The parent thread can send KILL signal to the vcpu thread when it was exiting which stops faulting pages and potentially allocating memory. So gfn_to_pfn/gfn_to_page may fail at this time Fixed by checking the page before it is used Signed-off-by: Xiao Guangrong --- arch/x86/kvm/vmx.c | 19 ++++++++++++++++--- arch/x86/kvm/x86.c | 13 ++++++++++--- 2 files changed, 26 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 248c2b4..ccea20a 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -3590,6 +3590,7 @@ static void seg_setup(int seg) static int alloc_apic_access_page(struct kvm *kvm) { + struct page *page; struct kvm_userspace_memory_region kvm_userspace_mem; int r = 0; @@ -3604,7 +3605,13 @@ static int alloc_apic_access_page(struct kvm *kvm) if (r) goto out; - kvm->arch.apic_access_page = gfn_to_page(kvm, 0xfee00); + page = gfn_to_page(kvm, 0xfee00); + if (is_error_page(page)) { + r = -EFAULT; + goto out; + } + + kvm->arch.apic_access_page = page; out: mutex_unlock(&kvm->slots_lock); return r; @@ -3612,6 +3619,7 @@ out: static int alloc_identity_pagetable(struct kvm *kvm) { + struct page *page; struct kvm_userspace_memory_region kvm_userspace_mem; int r = 0; @@ -3627,8 +3635,13 @@ static int alloc_identity_pagetable(struct kvm *kvm) if (r) goto out; - kvm->arch.ept_identity_pagetable = gfn_to_page(kvm, - kvm->arch.ept_identity_map_addr >> PAGE_SHIFT); + page = gfn_to_page(kvm, kvm->arch.ept_identity_map_addr >> PAGE_SHIFT); + if (is_error_page(page)) { + r = -EFAULT; + goto out; + } + + kvm->arch.ept_identity_pagetable = page; out: mutex_unlock(&kvm->slots_lock); return r; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index d8fba22..d44edaa 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5101,17 +5101,20 @@ static void post_kvm_run_save(struct kvm_vcpu *vcpu) !kvm_event_needs_reinjection(vcpu); } -static void vapic_enter(struct kvm_vcpu *vcpu) +static int vapic_enter(struct kvm_vcpu *vcpu) { struct kvm_lapic *apic = vcpu->arch.apic; struct page *page; if (!apic || !apic->vapic_addr) - return; + return 0; page = gfn_to_page(vcpu->kvm, apic->vapic_addr >> PAGE_SHIFT); + if (is_error_page(page)) + return -EFAULT; vcpu->arch.apic->vapic_page = page; + return 0; } static void vapic_exit(struct kvm_vcpu *vcpu) @@ -5418,7 +5421,11 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) } vcpu->srcu_idx = srcu_read_lock(&kvm->srcu); - vapic_enter(vcpu); + r = vapic_enter(vcpu); + if (r) { + srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx); + return r; + } r = 1; while (r > 0) {