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 C9705C433EF for ; Tue, 5 Oct 2021 09:02:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AF0D4610C7 for ; Tue, 5 Oct 2021 09:02:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233349AbhJEJEM (ORCPT ); Tue, 5 Oct 2021 05:04:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52082 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232884AbhJEJEJ (ORCPT ); Tue, 5 Oct 2021 05:04:09 -0400 Received: from mail-wr1-x44a.google.com (mail-wr1-x44a.google.com [IPv6:2a00:1450:4864:20::44a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F78DC061745 for ; Tue, 5 Oct 2021 02:02:19 -0700 (PDT) Received: by mail-wr1-x44a.google.com with SMTP id c2-20020adfa302000000b0015e4260febdso5474345wrb.20 for ; Tue, 05 Oct 2021 02:02:19 -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=miKQfMbrmMeNk1nN5Us0pRryucqshdMsoMrRtD78bnN0xpMXDyebUIGBm2N9+RsrjS UXs1cSibDRvi2j5buA7f3EAJmJVPTQXbPoOTBYvIY/gj/8Pk4xMg9LHmvDqHKoPbzWhj CKw2r5ZL72icTM4eRY5uiI5Cmba4u3bLD6i7BCUh0Di04EY+fYYHfezaua/ZlZ0xG3CC XzkqJunDQFO8KNIKYFbmJHYzFqBlmK9kO4mzgbotS+atB5CwSM97GuY5iOwp7Apy6CUd 9TDvI6JR/UrYgq52ZKMtEgOdcvtnUbgVt8CZhlFNzrhTdHOzXm/mu3rdOcnC9ZxCdibz l0sw== 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=3YeR5alWTBnPLdYerjfN0aJ9CFU06013ib8ueYOrEgtuayp5Pqr+8NS/hl93Z2Ah94 clrnKzElw4Agv+kP/bgHDNmo7Us5wtm2P7hAkEeexTDGzuTbNLlotaY9oBuUX1zm60It HdUG9tKhXapwqTktR08M32XPhlI4Y2YZtArEsb3ri4WTJQ+ptjjU3ObRpi/AUBBi2vLt NQ24bzhk5fToCPlp4w7aT5asDMd3yvjpjWy/RFb+yP3bERn8u3eaI66WuXjvIbFK3e7U LFaShrZ2gWTILpWNJpGvy8W7pUx7r5YDaJLZL1DL4IWW/lKmFSU1TiyR54nZWNc0Zqd9 EjDQ== X-Gm-Message-State: AOAM532+8C/i41zbImqs3AZ2pu04u7oIylwxZ+smJRpUfbxvTtb6ZpyC yFatPmTDlnFJDRSMrzp85zwT7HuFMTBg X-Google-Smtp-Source: ABdhPJwGSCqnQhZEyqfA74Q3qEcGbDWSwK0xwXi4KbcWnIWu2bbm4tNiHp9f0/QTwusKaq+9TcjstDkn7Ba3 X-Received: from luke.lon.corp.google.com ([2a00:79e0:d:210:5700:9128:3106:b389]) (user=qperret job=sendgmr) by 2002:a5d:4b50:: with SMTP id w16mr19856776wrs.71.1633424538044; Tue, 05 Oct 2021 02:02:18 -0700 (PDT) Date: Tue, 5 Oct 2021 10:01:38 +0100 In-Reply-To: <20211005090155.734578-1-qperret@google.com> Message-Id: <20211005090155.734578-2-qperret@google.com> Mime-Version: 1.0 References: <20211005090155.734578-1-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