From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD124C433E0 for ; Mon, 22 Jun 2020 20:09:18 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 6C40A207BC for ; Mon, 22 Jun 2020 20:09:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6C40A207BC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 254D14B0B3; Mon, 22 Jun 2020 16:09:18 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id TSgqZ5vMpbXl; Mon, 22 Jun 2020 16:09:17 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 9108F4B107; Mon, 22 Jun 2020 16:09:15 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 89CBC4B0EA for ; Mon, 22 Jun 2020 16:09:14 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ZqrZYSdYPvxA for ; Mon, 22 Jun 2020 16:09:13 -0400 (EDT) Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 14C8D4B0E2 for ; Mon, 22 Jun 2020 16:09:11 -0400 (EDT) IronPort-SDR: 43M/3nlYr4VEY5LcE0j3uFzpoWhIVwUQ9CUnv7hL5Nww+dG9au17msKZgOzKIadnzkd3eR+x75 LavExOB4R4Dw== X-IronPort-AV: E=McAfee;i="6000,8403,9660"; a="142921270" X-IronPort-AV: E=Sophos;i="5.75,268,1589266800"; d="scan'208";a="142921270" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jun 2020 13:09:10 -0700 IronPort-SDR: yGlHMVpx7tPbvz8MilBzAcb+zV5/r1q/UDwdXJHLNr+wYdW5D6lwBhGmwvh3BbwcOP7TP9cHQR F9Wk/ytWU0Yw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,268,1589266800"; d="scan'208";a="318877061" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.152]) by FMSMGA003.fm.intel.com with ESMTP; 22 Jun 2020 13:09:10 -0700 From: Sean Christopherson To: Marc Zyngier , Paolo Bonzini , Arnd Bergmann Subject: [PATCH v2 05/21] KVM: x86/mmu: Try to avoid crashing KVM if a MMU memory cache is empty Date: Mon, 22 Jun 2020 13:08:06 -0700 Message-Id: <20200622200822.4426-6-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200622200822.4426-1-sean.j.christopherson@intel.com> References: <20200622200822.4426-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Cc: linux-arch@vger.kernel.org, Junaid Shahid , Wanpeng Li , kvm@vger.kernel.org, Joerg Roedel , Peter Shier , linux-mips@vger.kernel.org, Sean Christopherson , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Ben Gardon , Vitaly Kuznetsov , Peter Feiner , kvmarm@lists.cs.columbia.edu, Jim Mattson X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Attempt to allocate a new object instead of crashing KVM (and likely the kernel) if a memory cache is unexpectedly empty. Use GFP_ATOMIC for the allocation as the caches are used while holding mmu_lock. The immediate BUG_ON() makes the code unnecessarily explosive and led to confusing minimums being used in the past, e.g. allocating 4 objects where 1 would suffice. Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu/mmu.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index ba70de24a5b0..5e773564ab20 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -1060,6 +1060,15 @@ static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu) local_irq_enable(); } +static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc, + gfp_t gfp_flags) +{ + if (mc->kmem_cache) + return kmem_cache_zalloc(mc->kmem_cache, gfp_flags); + else + return (void *)__get_free_page(gfp_flags); +} + static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min) { void *obj; @@ -1067,10 +1076,7 @@ static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min) if (mc->nobjs >= min) return 0; while (mc->nobjs < ARRAY_SIZE(mc->objects)) { - if (mc->kmem_cache) - obj = kmem_cache_zalloc(mc->kmem_cache, GFP_KERNEL_ACCOUNT); - else - obj = (void *)__get_free_page(GFP_KERNEL_ACCOUNT); + obj = mmu_memory_cache_alloc_obj(mc, GFP_KERNEL_ACCOUNT); if (!obj) return mc->nobjs >= min ? 0 : -ENOMEM; mc->objects[mc->nobjs++] = obj; @@ -1118,8 +1124,11 @@ static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc) { void *p; - BUG_ON(!mc->nobjs); - p = mc->objects[--mc->nobjs]; + if (WARN_ON(!mc->nobjs)) + p = mmu_memory_cache_alloc_obj(mc, GFP_ATOMIC | __GFP_ACCOUNT); + else + p = mc->objects[--mc->nobjs]; + BUG_ON(!p); return p; } -- 2.26.0 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm