Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751249AbaKBHIY (ORCPT ); Sun, 2 Nov 2014 02:08:24 -0500 Received: from mga01.intel.com ([192.55.52.88]:9914 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750820AbaKBHIW (ORCPT ); Sun, 2 Nov 2014 02:08:22 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,295,1413270000"; d="scan'208";a="615436318" From: Wanpeng Li To: Paolo Bonzini Cc: Takashi Iwai , Alexei Starovoitov , Tiejun Chen , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Wanpeng Li Subject: [PATCH v4] KVM: x86: fix access memslots w/o hold srcu read lock Date: Sun, 2 Nov 2014 15:07:43 +0800 Message-Id: <1414912063-10923-1-git-send-email-wanpeng.li@linux.intel.com> X-Mailer: git-send-email 1.7.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The srcu read lock must be held while accessing memslots (e.g. when using gfn_to_* functions), however, commit c24ae0dcd3e8 ("kvm: x86: Unpin and remove kvm_arch->apic_access_page") call gfn_to_page() in kvm_vcpu_reload_apic_access_page() w/o hold it in vmx_vcpu_reset() path which leads to suspicious rcu_dereference_check() usage warning. This patch fix it by holding srcu read lock in all kvm_vcpu_reset() call path. [ INFO: suspicious RCU usage. ] 3.18.0-rc2-test2+ #70 Not tainted ------------------------------- include/linux/kvm_host.h:474 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 0 1 lock held by qemu-system-x86/2371: #0: (&vcpu->mutex){+.+...}, at: [] vcpu_load+0x20/0xd0 [kvm] stack backtrace: CPU: 4 PID: 2371 Comm: qemu-system-x86 Not tainted 3.18.0-rc2-test2+ #70 Hardware name: Dell Inc. OptiPlex 9010/0M9KCM, BIOS A12 01/10/2013 0000000000000001 ffff880209983ca8 ffffffff816f514f 0000000000000000 ffff8802099b8990 ffff880209983cd8 ffffffff810bd687 00000000000fee00 ffff880208a2c000 ffff880208a10000 ffff88020ef50040 ffff880209983d08 Call Trace: [] dump_stack+0x4e/0x71 [] lockdep_rcu_suspicious+0xe7/0x120 [] gfn_to_memslot+0xd5/0xe0 [kvm] [] __gfn_to_pfn+0x33/0x60 [kvm] [] gfn_to_page+0x25/0x90 [kvm] [] kvm_vcpu_reload_apic_access_page+0x3c/0x80 [kvm] [] vmx_vcpu_reset+0x20c/0x460 [kvm_intel] [] kvm_vcpu_reset+0x15e/0x1b0 [kvm] [] kvm_arch_vcpu_setup+0x2c/0x50 [kvm] [] kvm_vm_ioctl+0x1d0/0x780 [kvm] [] ? __lock_is_held+0x54/0x80 [] do_vfs_ioctl+0x300/0x520 [] ? __fget+0x5/0x250 [] ? __fget_light+0x2a/0xe0 [] SyS_ioctl+0x81/0xa0 [] system_call_fastpath+0x16/0x1b Reported-by: Takashi Iwai Reported-by: Alexei Starovoitov Suggested-by: Paolo Bonzini Signed-off-by: Wanpeng Li --- v3 -> v4: * bypass the problem altoghter by kvm_make_request v2 -> v3: * take care all vmx_vcpu_reset call path v1 -> v2: * just fix hold the srcu read lock in vmx_vcpu_reset path arch/x86/kvm/vmx.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index a0f78db..3e556c6 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -4579,7 +4579,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu) vmcs_write32(TPR_THRESHOLD, 0); } - kvm_vcpu_reload_apic_access_page(vcpu); + kvm_make_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu); if (vmx_vm_has_apicv(vcpu->kvm)) memset(&vmx->pi_desc, 0, sizeof(struct pi_desc)); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/