From patchwork Fri Jun 21 09:38:24 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 11009581 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B8C026C5 for ; Fri, 21 Jun 2019 10:07:17 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A685A289B6 for ; Fri, 21 Jun 2019 10:07:17 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9A40B289EC; Fri, 21 Jun 2019 10:07:17 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 4E03A289B6 for ; Fri, 21 Jun 2019 10:07:17 +0000 (UTC) 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 1heGRw-0002Py-PG; Fri, 21 Jun 2019 10:07:16 +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 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP 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));