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=-8.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 CB525C43613 for ; Fri, 21 Jun 2019 10:07:18 +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 9EA15208CA for ; Fri, 21 Jun 2019 10:07:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="ONG2ES2i" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9EA15208CA 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:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=aAGnPhdODwYOxxBjqW8u8yez9xkfkQXCNKowMY8nx9A=; b=ONG2ES2iwjGRbd mm1uqRxyykNKcEWN6XM33aiUf+5Pizz0qtkeRb0eToS5FjaPJP747yC45tSQAutRYd0RZxTClGcCl vOigDo6pwk5WvA+KwVSJcGbkXBarLMVqLZTd1+vr0Jqz2VOlwm6Cj3ybR9LYRfde8kv03QSeInJ/j R9LXoCHxHvclDQpH4x5HrXG83vP5hOy3pzqhiH2LYdKR5nvrpG2Uu2fbw3Kec6GtS2+46obWuODu5 4dEa+xY6hmkx8k5xcPhuBTq6cqrgNZpCd/yn2/RHoqRH8Rqyu9OFhdjyqWzJG0CSP+6SyOAx9pv6m iTqt2+tHOXheHMPzszdw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1heGRv-0002Py-H6; Fri, 21 Jun 2019 10:07:15 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1heG1n-0000Hv-Pj for linux-arm-kernel@lists.infradead.org; Fri, 21 Jun 2019 09:40:25 +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 4D4701509; Fri, 21 Jun 2019 02:40:15 -0700 (PDT) Received: from filthy-habits.cambridge.arm.com (filthy-habits.cambridge.arm.com [10.1.197.61]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id EE0CD3F246; Fri, 21 Jun 2019 02:40:13 -0700 (PDT) From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org Subject: [PATCH 40/59] KVM: arm64: nv: Don't always start an S2 MMU search from the beginning Date: Fri, 21 Jun 2019 10:38:24 +0100 Message-Id: <20190621093843.220980-41-marc.zyngier@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190621093843.220980-1-marc.zyngier@arm.com> References: <20190621093843.220980-1-marc.zyngier@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190621_024015_961451_CB608BA2 X-CRM114-Status: GOOD ( 14.55 ) 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: Julien Thierry , Andre Przywara , Suzuki K Poulose , Christoffer Dall , Dave Martin , James Morse , Jintack Lim 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 Starting a S2 MMU search from the beginning all the time means that we're potentially nuking a useful context (like we'd potentially have on a !VHE KVM guest). Instead, let's always start the search from the point *after* the last allocated context. This should ensure that alternating between two EL1 contexts will not result in nuking the whole S2 each time. lookup_s2_mmu now has a chance to provide a hit. Signed-off-by: Marc Zyngier --- arch/arm64/include/asm/kvm_host.h | 1 + arch/arm64/kvm/nested.c | 14 ++++++++++++-- 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index b71a7a237f95..b7c44adcdbf3 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -123,6 +123,7 @@ struct kvm_arch { */ struct kvm_s2_mmu *nested_mmus; size_t nested_mmus_size; + int nested_mmus_next; /* VTCR_EL2 value for this VM */ u64 vtcr; diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index 09afafbdc8fe..214d59019935 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -363,14 +363,24 @@ static struct kvm_s2_mmu *get_s2_mmu_nested(struct kvm_vcpu *vcpu) if (s2_mmu) goto out; - for (i = 0; i < kvm->arch.nested_mmus_size; i++) { - s2_mmu = &kvm->arch.nested_mmus[i]; + /* + * Make sure we don't always search from the same point, or we + * will always reuse a potentially active context, leaving + * free contexts unused. + */ + for (i = kvm->arch.nested_mmus_next; + i < (kvm->arch.nested_mmus_size + kvm->arch.nested_mmus_next); + i++) { + s2_mmu = &kvm->arch.nested_mmus[i % kvm->arch.nested_mmus_size]; if (atomic_read(&s2_mmu->refcnt) == 0) break; } BUG_ON(atomic_read(&s2_mmu->refcnt)); /* We have struct MMUs to spare */ + /* Set the scene for the next search */ + kvm->arch.nested_mmus_next = (i + 1) % kvm->arch.nested_mmus_size; + if (kvm_s2_mmu_valid(s2_mmu)) { /* Clear the old state */ kvm_unmap_stage2_range(s2_mmu, 0, kvm_phys_size(kvm)); -- 2.20.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel