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 X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5AAD0C54E8B for ; Tue, 12 May 2020 12:04:47 +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 2924620674 for ; Tue, 12 May 2020 12:04:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="I4uWAHMK" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2924620674 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.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:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=gS/zZ8drceq/yzgb/0YydAO4cy8Ge6DfKYssm4uZfmY=; b=I4uWAHMKOMiBNG UWv0q2cQPYdLBp7BK5HViSMacKF9okXEArVGjn6sELgn8DZfC/S9riSJnHp3S94RRNsKm2KUbwwOQ KvqwyyL41LoDFasgPcv9gkiORbWKDJE49wXM4I1sEt/tZ8h86QX9KcXOeDYSC6T/nNKRwqjlNFz+q GBSCOzoLUC62TuFdxU+XlmL1ul0XPTgIVyBpYw5S55utADQbaaiXOJ/JXbCT+KOydfyDlaKxyKdzB 3t9fPvPJN/xYWAN/7DFW9MfA75iofkgrUGhHAdEFmdUny3O3wLiFTGkHpRNaNdUVOYRWINGrxLUzF 7oxi4X+Q8PbR47JF8k9g==; 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 1jYTeN-0001gp-R3; Tue, 12 May 2020 12:04:43 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jYTeK-0001fs-1b for linux-arm-kernel@lists.infradead.org; Tue, 12 May 2020 12:04:42 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 073B130E; Tue, 12 May 2020 05:04:38 -0700 (PDT) Received: from [192.168.0.14] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9F7063F71E; Tue, 12 May 2020 05:04:36 -0700 (PDT) Subject: Re: [PATCH 08/26] KVM: arm64: Use TTL hint in when invalidating stage-2 translations To: Andrew Scull References: <20200422120050.3693593-1-maz@kernel.org> <20200422120050.3693593-9-maz@kernel.org> <20200507151321.GH237572@google.com> From: James Morse Message-ID: <63e16fdd-fe1b-07d3-23b7-cd99170fdd59@arm.com> Date: Tue, 12 May 2020 13:04:31 +0100 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20200507151321.GH237572@google.com> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200512_050440_522583_4659A6B3 X-CRM114-Status: GOOD ( 12.23 ) 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: Catalin Marinas , kvm@vger.kernel.org, Marc Zyngier , Dave Martin , George Cherian , "Zengtao \(B\)" , Andre Przywara , Will Deacon , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Andrew, On 07/05/2020 16:13, Andrew Scull wrote: >> @@ -176,7 +177,7 @@ static void clear_stage2_pud_entry(struct kvm_s2_mmu *mmu, pud_t *pud, phys_addr >> pmd_t *pmd_table __maybe_unused = stage2_pmd_offset(kvm, pud, 0); >> VM_BUG_ON(stage2_pud_huge(kvm, *pud)); >> stage2_pud_clear(kvm, pud); >> - kvm_tlb_flush_vmid_ipa(mmu, addr); >> + kvm_tlb_flush_vmid_ipa(mmu, addr, S2_NO_LEVEL_HINT); >> stage2_pmd_free(kvm, pmd_table); >> put_page(virt_to_page(pud)); >> } >> @@ -186,7 +187,7 @@ static void clear_stage2_pmd_entry(struct kvm_s2_mmu *mmu, pmd_t *pmd, phys_addr >> pte_t *pte_table = pte_offset_kernel(pmd, 0); >> VM_BUG_ON(pmd_thp_or_huge(*pmd)); >> pmd_clear(pmd); >> - kvm_tlb_flush_vmid_ipa(mmu, addr); >> + kvm_tlb_flush_vmid_ipa(mmu, addr, S2_NO_LEVEL_HINT); >> free_page((unsigned long)pte_table); >> put_page(virt_to_page(pmd)); >> } > > Going by the names, is it possible to give a better level hint for these > cases? There is no leaf entry being invalidated here. After clearing the range, we found we'd emptied (and invalidated) a whole page of mappings: | if (stage2_pmd_table_empty(kvm, start_pmd)) | clear_stage2_pud_entry(mmu, pud, start_addr); Now we want to remove the link to the empty page so we can free it. We are changing the structure of the tables, not what gets mapped. I think this is why we need the un-hinted behaviour, to invalidate "any level of the translation table walk required to translate the specified IPA". Otherwise the hardware can look for a leaf at the indicated level, find none, and do nothing. This is sufficiently horrible, its possible I've got it completely wrong! (does it make sense?) Thanks, James _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel