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 D56ADC433EF for ; Tue, 5 Oct 2021 09:03:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BABE461251 for ; Tue, 5 Oct 2021 09:03:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233462AbhJEJE6 (ORCPT ); Tue, 5 Oct 2021 05:04:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52286 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232511AbhJEJE5 (ORCPT ); Tue, 5 Oct 2021 05:04:57 -0400 Received: from mail-wr1-x449.google.com (mail-wr1-x449.google.com [IPv6:2a00:1450:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BAA79C061745 for ; Tue, 5 Oct 2021 02:03:06 -0700 (PDT) Received: by mail-wr1-x449.google.com with SMTP id d13-20020adfa34d000000b00160aa1cc5f1so1800252wrb.14 for ; Tue, 05 Oct 2021 02:03:06 -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=Zg+gUiu3ox2wHV7TW+7r/xAJBwKqffZp8cWRWiJTXrY=; b=ethTiy3lTzcSneIbLwawi+5olik16z23jgqCFT9E6S+igJ69OtJ1TPMCM3LUeMuDWh kwcRJn93q32+YoPQuqYwcmM2DdY9Fe9IYJKgK+GXLbcXpWzMDJRW3LbNqRmKiJUsc6DC CebD0o+l0nqeRevVQD1bAdXZQHBHCWfG8Rcoy58tJcFsFAxUPA0SJI81RMitxFI9xF+C YxiAvhisoF3VIur01ICFsq3MrvN2eqrXvL8fZNMl/vG0AqdzcjPWDTaTqFZDJuk+h9ab QCMcSvBsSTabymd8vvOKuV6YemDU3oBdSpPn6xfZo8O6vSq3YJh46dvt7fuELrY2dzVh x/ig== 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=Zg+gUiu3ox2wHV7TW+7r/xAJBwKqffZp8cWRWiJTXrY=; b=YpZrlqusGBxxtbiJaym5EQXFrwrgVWqpDU0J9sjs4d2F+SEnPWrxXSLHyz3sCyyocU 5qJYCNS2qkAHRFQCPsu2jdDs6XSkkVI4dNTgRa3u++yskgSDQXM9S41IoURw0SrytVc4 CZlatdgH41+wqv/TNc8cVY0rGllp/vT9X5hklF0EEguhMS+WtsOvXYMfMjB4T59VcKb/ NoxinSDULAgSud2InIkWU5i3PruWvkwYFxxbihcfOCKNZ5iMzoTgDqVb79x+eyMXiDvS 2F1mcXqqlPxCu29oiCBIDd9lb+Wrm9uVqr/WVBLfshyCs2V9DZZwnFUKvD9TpylBhdCs p3mw== X-Gm-Message-State: AOAM5338zEcHbvCj7lYnDGS962DR6/pVgXUx9vShc0dmrIsc5ADxnWJ6 eKgK1Saoj5v0/95PhaKe8w+CmtGAG9vU X-Google-Smtp-Source: ABdhPJxUSKr1FTBsupYcr01qanV2kSzxpxGMspE323G2ZVQjyutuN9ik2CBJcXODTdTUv+X78VCL5yV8AtM/ X-Received: from luke.lon.corp.google.com ([2a00:79e0:d:210:5700:9128:3106:b389]) (user=qperret job=sendgmr) by 2002:adf:a45e:: with SMTP id e30mr18268872wra.269.1633424585068; Tue, 05 Oct 2021 02:03:05 -0700 (PDT) Date: Tue, 5 Oct 2021 10:01:41 +0100 In-Reply-To: <20211005090155.734578-1-qperret@google.com> Message-Id: <20211005090155.734578-5-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 v2 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, when running KVM in protected mode, 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 shouldn't, hence corrupting the page-table. Fix this by introducing a new hyp_split_page() helper in the EL2 page allocator (matching the kernel's split_page() function), and make use of it from host_s2_zalloc_pages_exact(). Fixes: 1025c8c0c6ac ("KVM: arm64: Wrap the host with a stage 2") Acked-by: Will Deacon 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 | 13 ++++++++++++- arch/arm64/kvm/hyp/nvhe/page_alloc.c | 14 ++++++++++++++ 3 files changed, 27 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..34eeb524b686 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -35,7 +35,18 @@ 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)); + + /* + * The size of concatenated PGDs is always a power of two of PAGE_SIZE, + * so there should be no need to free any of the tail pages to make the + * allocation exact. + */ + WARN_ON(size != (PAGE_SIZE << get_order(size))); + + 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