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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE516C433EF for ; Mon, 4 Oct 2021 09:04:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9E0FE61425 for ; Mon, 4 Oct 2021 09:04:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231598AbhJDJFs (ORCPT ); Mon, 4 Oct 2021 05:05:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229716AbhJDJFr (ORCPT ); Mon, 4 Oct 2021 05:05:47 -0400 Received: from mail-qv1-xf49.google.com (mail-qv1-xf49.google.com [IPv6:2607:f8b0:4864:20::f49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D81A6C061745 for ; Mon, 4 Oct 2021 02:03:58 -0700 (PDT) Received: by mail-qv1-xf49.google.com with SMTP id l18-20020a056214039200b0037e4da8b408so17781476qvy.6 for ; Mon, 04 Oct 2021 02:03:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=tHk4fNmSvcmkrUgevYD4U41Hr/4Newl1f8mzt2RPUWc=; b=myW/CpAigjPZ2o/T9HjLhLXbZVJxyS9JodGVVoxwHVcl/oDBQWttTnf0/LE1PwwT89 gKHppZ/CIgxO5msodZmnUfQBvJdqFUxdYc2bpazuwiq6sHG2QRGBrRuLvZr9ama7hWIy ZMJVyyU+o0d18Ju2reVMrpwo7YeU6Ga9AixILWDG8AnRm/y8T+cOnFt3lc+f0kCaWJdY pnU5kjI5gSCdVuPAbJjWYsFQ5TkKHM5RnmPP8Cax+hFd8/qzWgC9yJEvhQaq+CaYCveL mPuIgKFgnPJ9kaD32mXvPB1nryO78HAjInlK0UW7Z7MGbp2HyWIXaRHkD94LZXB0c6Xr UHRg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=tHk4fNmSvcmkrUgevYD4U41Hr/4Newl1f8mzt2RPUWc=; b=daaK9mIciUquFRY/OzUESo8hEMSWABTlOGkqnrqU8v9yHUzyprgYH/q4QqEFxMJLNG 7nMv0wK9KkABVO7X70FDhLVdSDpgwPGSRcJWO0EqImBzTie67IQEBqtmHVxeFIQfUPuW MQQSK8e15bOGO9EH/bPTOOgh1Y/kWxuKab551YvFg4pVKuU09vY4vA4LCy82PmFcQRqh w4XQ3TxsWmVA63ST1q9pkKyCtzEUrt5O0dhNYAe66JXSjWWjfCt7g6P1M6gle6a1G/yE CnwRfV6Pw/q3t/g0FbrKN81PzVTpsVeWTFkbONZ3xvndyuYBmCcbXc6hSI4H8C9BGCAJ ZkPA== X-Gm-Message-State: AOAM533lp82ZI+D1PS8FZnyMPgrr6wytJ0qgSAvKffkd3HXnmCdXQ9jo O9YUwMX0kO3noTvtwe6E1EHAqyhfnYqI X-Google-Smtp-Source: ABdhPJycEaMXqOovXmHOEABw2fHm7gyvxCA3r77eIjHFoIIvQP3KmydvfcyBUYygJRYLqZ5CcnPGaqUsZunc X-Received: from luke.lon.corp.google.com ([2a00:79e0:d:210:669b:5b16:60b7:a3d4]) (user=qperret job=sendgmr) by 2002:a05:6214:c47:: with SMTP id r7mr4515752qvj.12.1633338238007; Mon, 04 Oct 2021 02:03:58 -0700 (PDT) Date: Mon, 4 Oct 2021 10:03:13 +0100 In-Reply-To: <20211004090328.540941-1-qperret@google.com> Message-Id: <20211004090328.540941-2-qperret@google.com> Mime-Version: 1.0 References: <20211004090328.540941-1-qperret@google.com> X-Mailer: git-send-email 2.33.0.800.g4c38ced690-goog Subject: [PATCH 1/2] KVM: arm64: Fix host stage-2 PGD refcount From: Quentin Perret To: Marc Zyngier , James Morse , Alexandru Elisei , Suzuki K Poulose , Catalin Marinas , Will Deacon , Quentin Perret , Fuad Tabba , David Brazdil , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org Cc: kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The KVM page-table library refcounts the pages of concatenated stage-2 PGDs individually. However, the host's stage-2 PGD is currently managed by EL2 as a single high-order compound page, which can cause the refcount of the tail pages to reach 0 when they really shouldn't, hence corrupting the page-table. Fix this by introducing a new hyp_split_page() helper in the EL2 page allocator (matching EL1's split_page() function), and make use of it from host_s2_zalloc_page(). Fixes: 1025c8c0c6ac ("KVM: arm64: Wrap the host with a stage 2") Suggested-by: Will Deacon Signed-off-by: Quentin Perret --- arch/arm64/kvm/hyp/include/nvhe/gfp.h | 1 + arch/arm64/kvm/hyp/nvhe/mem_protect.c | 6 +++++- arch/arm64/kvm/hyp/nvhe/page_alloc.c | 14 ++++++++++++++ 3 files changed, 20 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/hyp/include/nvhe/gfp.h b/arch/arm64/kvm/hyp/include/nvhe/gfp.h index fb0f523d1492..0a048dc06a7d 100644 --- a/arch/arm64/kvm/hyp/include/nvhe/gfp.h +++ b/arch/arm64/kvm/hyp/include/nvhe/gfp.h @@ -24,6 +24,7 @@ struct hyp_pool { /* Allocation */ void *hyp_alloc_pages(struct hyp_pool *pool, unsigned short order); +void hyp_split_page(struct hyp_page *page); void hyp_get_page(struct hyp_pool *pool, void *addr); void hyp_put_page(struct hyp_pool *pool, void *addr); diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c index bacd493a4eac..93a79736c283 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -35,7 +35,11 @@ const u8 pkvm_hyp_id = 1; static void *host_s2_zalloc_pages_exact(size_t size) { - return hyp_alloc_pages(&host_s2_pool, get_order(size)); + void *addr = hyp_alloc_pages(&host_s2_pool, get_order(size)); + + hyp_split_page(hyp_virt_to_page(addr)); + + return addr; } static void *host_s2_zalloc_page(void *pool) diff --git a/arch/arm64/kvm/hyp/nvhe/page_alloc.c b/arch/arm64/kvm/hyp/nvhe/page_alloc.c index 41fc25bdfb34..a6e874e61a40 100644 --- a/arch/arm64/kvm/hyp/nvhe/page_alloc.c +++ b/arch/arm64/kvm/hyp/nvhe/page_alloc.c @@ -193,6 +193,20 @@ void hyp_get_page(struct hyp_pool *pool, void *addr) hyp_spin_unlock(&pool->lock); } +void hyp_split_page(struct hyp_page *p) +{ + unsigned short order = p->order; + unsigned int i; + + p->order = 0; + for (i = 1; i < (1 << order); i++) { + struct hyp_page *tail = p + i; + + tail->order = 0; + hyp_set_page_refcounted(tail); + } +} + void *hyp_alloc_pages(struct hyp_pool *pool, unsigned short order) { unsigned short i = order; -- 2.33.0.800.g4c38ced690-goog