From patchwork Fri Oct 7 23:28:12 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oliver Upton X-Patchwork-Id: 13001531 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id DE938C433FE for ; Fri, 7 Oct 2022 23:32:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=VMKq4QSeQwq/5zgE+e+ePUF/AYXR7IZPJlKVtt0ppa0=; b=ocnauPDSSaATG1 KSGEmyYeRcTC+4Q6xt8cLAUnn5hd14qC6aHLGoJVg3ekyjZsnVgA5MmjifMpBKPBb5qr6InROee8r xcJ2jY45j24wz5XBSyLUh+9x7fXhAKl3sczIi15Mv2kMO//zfhLycAla06kB8bqNgWeqjSQho5HdW +d1aMR0UEqEWdKyAGqh5C6XCRwlgq3zlQdoMjkxVUgDQLglvhIPuGUzsxrF8JP784jnGEqMo06SjI UkwZKl9ft95GUNosaES0BCQGgLvC+IERtHhMUj0dSAsoK+Qw9F3Fl7zqv8kInWMapjLvZpibBH9bg J3+ul+Ogsof8jHBotztA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ogwoJ-00At5x-0v; Fri, 07 Oct 2022 23:31:19 +0000 Received: from out0.migadu.com ([2001:41d0:2:267::]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ogwmS-00AsAg-6O for linux-arm-kernel@lists.infradead.org; Fri, 07 Oct 2022 23:29:25 +0000 X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1665185362; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=VSPfpEbpaF1HVCxRtymHK1iFw2Ndlq59kfZN9gAzh+o=; b=cNg6oTFgzO6GY0L1TSYs7VSjRhECOO45tRYmyHyGTLCGVfbUe1OMQZDUhlHB5r2lpF6zDS 2D+3RKe920GacKOattZz33WA70jNktLYMN/nLuxTOfrgoBEWrnF636GWOmA8Torc/pEFPj QL2sulno3gIzHRFCHhAZJcOqkha0/VA= From: Oliver Upton To: Marc Zyngier , James Morse , Alexandru Elisei Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, Reiji Watanabe , Ricardo Koller , David Matlack , Quentin Perret , Ben Gardon , Gavin Shan , Peter Xu , Will Deacon , Sean Christopherson , kvmarm@lists.linux.dev, Oliver Upton Subject: [PATCH v2 09/15] KVM: arm64: Free removed stage-2 tables in RCU callback Date: Fri, 7 Oct 2022 23:28:12 +0000 Message-Id: <20221007232818.459650-10-oliver.upton@linux.dev> In-Reply-To: <20221007232818.459650-1-oliver.upton@linux.dev> References: <20221007232818.459650-1-oliver.upton@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221007_162924_413893_5F9ACA68 X-CRM114-Status: UNSURE ( 9.86 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org There is no real urgency to free a stage-2 subtree that was pruned. Nonetheless, KVM does the tear down in the stage-2 fault path while holding the MMU lock. Free removed stage-2 subtrees after an RCU grace period. To guarantee all stage-2 table pages are freed before killing a VM, add an rcu_barrier() to the flush path. Signed-off-by: Oliver Upton --- arch/arm64/kvm/mmu.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 04a25319abb0..66eede0fbb36 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -104,9 +104,21 @@ static void *kvm_host_zalloc_pages_exact(size_t size) static struct kvm_pgtable_mm_ops kvm_s2_mm_ops; +static void stage2_free_removed_table_rcu_cb(struct rcu_head *head) +{ + struct page *page = container_of(head, struct page, rcu_head); + void *pgtable = page_to_virt(page); + u32 level = page_private(page); + + kvm_pgtable_stage2_free_removed(&kvm_s2_mm_ops, pgtable, level); +} + static void stage2_free_removed_table(void *addr, u32 level) { - kvm_pgtable_stage2_free_removed(&kvm_s2_mm_ops, addr, level); + struct page *page = virt_to_page(addr); + + set_page_private(page, (unsigned long)level); + call_rcu(&page->rcu_head, stage2_free_removed_table_rcu_cb); } static void kvm_host_get_page(void *addr)