From patchwork Fri Jun 5 21:38:37 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 11590627 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3BF0C92A for ; Fri, 5 Jun 2020 21:41:34 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 077AD20772 for ; Fri, 5 Jun 2020 21:41:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="bhgZx1Cp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 077AD20772 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=eAoEu40zKdpxsw9B6OLDu9g5CFjBlRHO02JDk+Zatvk=; b=bhgZx1CpM0q73Y wZvByVqFVl9DOpk4+L8NrqWxOQnTc4GJWf0Y7YOxy+1x1bnIEZNmkXpLW+x4GhIvfM0sXpeMo13+o EFlcAOGzG0gnvMSh3HjVS/OBoEySyNuFI9Jzuxtnf5/njRc4N4yl9JwYWxECHpjaC7I3lHUaSLADy SZPOut9Ev4KVfzYBWhKE1Uk4M0X0q5oa2r35SQuJG/GdIAoJEw5zF3gvPXJRlJLD4k991Nw4o8R8W raAz3AiNCORSf1VR7uJ1/WvHArmmBdhkcWFfXRdIJrGGwkgmHyZE+xfJw58KZ1IzUhfbRjeX2zYl9 qL94DKdSdsKTbU6GVmkw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jhK5d-00075W-I4; Fri, 05 Jun 2020 21:41:25 +0000 Received: from mga17.intel.com ([192.55.52.151]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jhK3U-0002lz-AB for linux-arm-kernel@lists.infradead.org; Fri, 05 Jun 2020 21:39:14 +0000 IronPort-SDR: GYCxHtskTuuXVy5UDojJgnShJLFCVwbmGn/E4r4JApgk8HuNjjMw2FqY2JDwmAV8ukXNj0QRVT 9Vb6qPGGjfOQ== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Jun 2020 14:39:08 -0700 IronPort-SDR: /DIB9oiqYI2Fg3zD1AVI7xOqUEPZThNOBLFZjDo1clHWgdOMBdzQcqRgIJ9S8j4GwRp7A7TrVS UbqM0qM5y0jg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,477,1583222400"; d="scan'208";a="287860880" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.152]) by orsmga002.jf.intel.com with ESMTP; 05 Jun 2020 14:39:07 -0700 From: Sean Christopherson To: Marc Zyngier , Paul Mackerras , Christian Borntraeger , Janosch Frank , Paolo Bonzini Subject: [PATCH 05/21] KVM: x86/mmu: Try to avoid crashing KVM if a MMU memory cache is empty Date: Fri, 5 Jun 2020 14:38:37 -0700 Message-Id: <20200605213853.14959-6-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200605213853.14959-1-sean.j.christopherson@intel.com> References: <20200605213853.14959-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200605_143912_378704_625715D0 X-CRM114-Status: GOOD ( 11.45 ) X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [192.55.52.151 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Wanpeng Li , kvm@vger.kernel.org, David Hildenbrand , linux-mips@vger.kernel.org, Ben Gardon , Claudio Imbrenda , kvmarm@lists.cs.columbia.edu, Joerg Roedel , Julien Thierry , Junaid Shahid , Suzuki K Poulose , kvm-ppc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Jim Mattson , Cornelia Huck , Peter Shier , Christoffer Dall , Sean Christopherson , linux-kernel@vger.kernel.org, James Morse , Vitaly Kuznetsov , Peter Feiner Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org 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 Reviewed-by: Ben Gardon --- 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; }