From patchwork Tue Jul 26 11:25:14 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiao Guangrong X-Patchwork-Id: 1007762 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter1.kernel.org (8.14.4/8.14.4) with ESMTP id p6QBNbxu008591 for ; Tue, 26 Jul 2011 11:23:37 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753169Ab1GZLXR (ORCPT ); Tue, 26 Jul 2011 07:23:17 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:57620 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753131Ab1GZLXQ (ORCPT ); Tue, 26 Jul 2011 07:23:16 -0400 Received: from tang.cn.fujitsu.com (tang.cn.fujitsu.com [10.167.250.3]) by song.cn.fujitsu.com (Postfix) with ESMTP id 7C1CA170044; Tue, 26 Jul 2011 19:23:14 +0800 (CST) Received: from mailserver.fnst.cn.fujitsu.com (tang.cn.fujitsu.com [127.0.0.1]) by tang.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id p6QBNDoa010782; Tue, 26 Jul 2011 19:23:14 +0800 Received: from localhost.localdomain ([10.167.225.99]) by mailserver.fnst.cn.fujitsu.com (Lotus Domino Release 8.5.1FP4) with ESMTP id 2011072619222102-20046 ; Tue, 26 Jul 2011 19:22:21 +0800 Message-ID: <4E2EA41A.3080606@cn.fujitsu.com> Date: Tue, 26 Jul 2011 19:25:14 +0800 From: Xiao Guangrong User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110428 Fedora/3.1.10-1.fc15 Thunderbird/3.1.10 MIME-Version: 1.0 To: Avi Kivity CC: Marcelo Tosatti , LKML , KVM Subject: [PATCH 01/11] KVM: MMU: avoid pte_list_desc run out in kvm_mmu_pte_write References: <4E2EA3DB.7040403@cn.fujitsu.com> In-Reply-To: <4E2EA3DB.7040403@cn.fujitsu.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-07-26 19:22:21, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-07-26 19:22:21, Serialize complete at 2011-07-26 19:22:21 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter1.kernel.org [140.211.167.41]); Tue, 26 Jul 2011 11:23:37 +0000 (UTC) kvm_mmu_pte_write is unsafe since we need to alloc pte_list_desc in the function when spte is prefetched, unfortunately, we can not know how many spte need to be prefetched on this path, that means we can use out of the free pte_list_desc object in the cache, and BUG_ON() is triggered, also some path does not fill the cache, such as INS instruction emulated that does not trigger page fault Signed-off-by: Xiao Guangrong --- arch/x86/kvm/mmu.c | 20 +++++++++++++++----- 1 files changed, 15 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 9335e1b..587695b 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -593,6 +593,11 @@ static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache, return 0; } +static int mmu_memory_cache_free_object(struct kvm_mmu_memory_cache *cache) +{ + return cache->nobjs; +} + static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc, struct kmem_cache *cache) { @@ -3526,6 +3531,14 @@ static void kvm_mmu_access_page(struct kvm_vcpu *vcpu, gfn_t gfn) set_bit(PT_ACCESSED_SHIFT, (unsigned long *)spte); } +static int get_free_pte_list_desc_nr(struct kvm_vcpu *vcpu) +{ + struct kvm_mmu_memory_cache *cache; + + cache = &vcpu->arch.mmu_pte_list_desc_cache; + return mmu_memory_cache_free_object(cache); +} + void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, int bytes, bool guest_initiated) @@ -3583,6 +3596,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, break; } + mmu_topup_memory_caches(vcpu); spin_lock(&vcpu->kvm->mmu_lock); if (atomic_read(&vcpu->kvm->arch.invlpg_counter) != invlpg_counter) gentry = 0; @@ -3653,7 +3667,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, mmu_page_zap_pte(vcpu->kvm, sp, spte); if (gentry && !((sp->role.word ^ vcpu->arch.mmu.base_role.word) - & mask.word)) + & mask.word) && get_free_pte_list_desc_nr(vcpu)) mmu_pte_write_new_pte(vcpu, sp, spte, &gentry); if (!remote_flush && need_remote_flush(entry, *spte)) remote_flush = true; @@ -3714,10 +3728,6 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code, goto out; } - r = mmu_topup_memory_caches(vcpu); - if (r) - goto out; - er = x86_emulate_instruction(vcpu, cr2, 0, insn, insn_len); switch (er) {