Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754837AbWL1NLH (ORCPT ); Thu, 28 Dec 2006 08:11:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754840AbWL1NLH (ORCPT ); Thu, 28 Dec 2006 08:11:07 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:41118 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754837AbWL1NLG (ORCPT ); Thu, 28 Dec 2006 08:11:06 -0500 Date: Thu, 28 Dec 2006 14:08:33 +0100 From: Ingo Molnar To: Avi Kivity Cc: kvm-devel , linux-kernel , Andrew Morton , Linus Torvalds Subject: [patch, try#2] kvm: fix GFP_KERNEL allocation in atomic section in kvm_dev_ioctl_create_vcpu() Message-ID: <20061228130833.GA555@elte.hu> References: <45939755.7010603@qumranet.com> <20061228124224.GA28573@elte.hu> <4593BEE6.30206@qumranet.com> <20061228125544.GA31207@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20061228125544.GA31207@elte.hu> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -5.9 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-5.9 required=5.9 tests=ALL_TRUSTED,BAYES_00 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts -2.6 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3565 Lines: 122 * Ingo Molnar wrote: > > Yes it does. It calls nonpaging_init_context() which calls > > vmx_set_cr3() which promptly trashes address space of the VM that > > previously ran on that vcpu (or, if there were none, logs a vmwrite > > error). > > ok, i missed that. Nevertheless the problem of the nonatomic alloc > remains. I guess a kvm_mmu_init() needs to be split into > kvm_mmu_create() and kvm_mmu_setup()? the patch below implements this fix. Lightly tested on 32-bit/VMX on 2.6.20-rc2-rt2 but seems to have done the trick. Ingo --------------------> Subject: [patch] kvm: fix GFP_KERNEL allocation in atomic section in kvm_dev_ioctl_create_vcpu() From: Ingo Molnar fix an GFP_KERNEL allocation in atomic section: kvm_dev_ioctl_create_vcpu() called kvm_mmu_init(), which calls alloc_pages(), while holding the vcpu. The fix is to set up the MMU state in two phases: kvm_mmu_create() and kvm_mmu_setup(). (NOTE: free_vcpus does an kvm_mmu_destroy() call so there's no need for any extra teardown branch on allocation/init failure here.) Signed-off-by: Ingo Molnar --- drivers/kvm/kvm.h | 3 ++- drivers/kvm/kvm_main.c | 10 ++++++---- drivers/kvm/mmu.c | 24 +++++++++--------------- 3 files changed, 17 insertions(+), 20 deletions(-) Index: linux/drivers/kvm/kvm.h =================================================================== --- linux.orig/drivers/kvm/kvm.h +++ linux/drivers/kvm/kvm.h @@ -319,7 +319,8 @@ int kvm_init_arch(struct kvm_arch_ops *o void kvm_exit_arch(void); void kvm_mmu_destroy(struct kvm_vcpu *vcpu); -int kvm_mmu_init(struct kvm_vcpu *vcpu); +int kvm_mmu_create(struct kvm_vcpu *vcpu); +int kvm_mmu_setup(struct kvm_vcpu *vcpu); int kvm_mmu_reset_context(struct kvm_vcpu *vcpu); void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot); Index: linux/drivers/kvm/kvm_main.c =================================================================== --- linux.orig/drivers/kvm/kvm_main.c +++ linux/drivers/kvm/kvm_main.c @@ -522,12 +522,14 @@ static int kvm_dev_ioctl_create_vcpu(str if (r < 0) goto out_free_vcpus; - kvm_arch_ops->vcpu_load(vcpu); + r = kvm_mmu_create(vcpu); + if (r < 0) + goto out_free_vcpus; - r = kvm_arch_ops->vcpu_setup(vcpu); + kvm_arch_ops->vcpu_load(vcpu); + r = kvm_mmu_setup(vcpu); if (r >= 0) - r = kvm_mmu_init(vcpu); - + r = kvm_arch_ops->vcpu_setup(vcpu); vcpu_put(vcpu); if (r < 0) Index: linux/drivers/kvm/mmu.c =================================================================== --- linux.orig/drivers/kvm/mmu.c +++ linux/drivers/kvm/mmu.c @@ -639,28 +639,22 @@ error_1: return -ENOMEM; } -int kvm_mmu_init(struct kvm_vcpu *vcpu) +int kvm_mmu_create(struct kvm_vcpu *vcpu) { - int r; - ASSERT(vcpu); ASSERT(!VALID_PAGE(vcpu->mmu.root_hpa)); ASSERT(list_empty(&vcpu->free_pages)); - r = alloc_mmu_pages(vcpu); - if (r) - goto out; - - r = init_kvm_mmu(vcpu); - if (r) - goto out_free_pages; + return alloc_mmu_pages(vcpu); +} - return 0; +int kvm_mmu_setup(struct kvm_vcpu *vcpu) +{ + ASSERT(vcpu); + ASSERT(!VALID_PAGE(vcpu->mmu.root_hpa)); + ASSERT(!list_empty(&vcpu->free_pages)); -out_free_pages: - free_mmu_pages(vcpu); -out: - return r; + return init_kvm_mmu(vcpu); } void kvm_mmu_destroy(struct kvm_vcpu *vcpu) - 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/