From patchwork Mon Sep 9 13:48:01 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 11138015 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A9FEA76 for ; Mon, 9 Sep 2019 13:52:07 +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 876562196E for ; Mon, 9 Sep 2019 13:52:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="raRh8NrT" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 876562196E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.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=PKUQagOAB0xmsZZpdDUGafbWy9DxROuFOLGWyFAXNnM=; b=raRh8NrTAKM/7P vxrgKgjpN+Rw6hZ48+JWsBZSkbNIf0CsuvRvYe6s64vnXaP+nKDJzTNWBtrAQ4yLSLELdFpVpggNl kWd52ruW9TK2pyYzxEhFWLaxzVcxL9vjvFO8Qmo1ub+Is9emwHNjG7hBAra/Y0wflq39c5xkhdHTG oN6pkZsvseLvMY3Ku/COkW42mQ0WDU/8QzZF0ZwxF0svbLewpV9y8TVpjQ/zzkMzGkz4Ul2V55Z7W YGFj1q15jMOljoTPUXJzidvnvmuxGzQEvAozi6M53wq6WNVigo8F/wGNRltcayp6Uq+yiLZA36cvq S02nzsJcwIPGTIc+nKiw==; 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 1i7K5K-0006By-Dz; Mon, 09 Sep 2019 13:52:02 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i7K2h-0002e5-EU for linux-arm-kernel@lists.infradead.org; Mon, 09 Sep 2019 13:49:21 +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 F126319F6; Mon, 9 Sep 2019 06:49:18 -0700 (PDT) Received: from localhost.localdomain (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C2A6F3F59C; Mon, 9 Sep 2019 06:49:16 -0700 (PDT) From: Marc Zyngier To: Paolo Bonzini , =?utf-8?b?UmFkaW0gS3LEjW3DocWZ?= Subject: [PATCH 11/17] arm64/kvm: Remove VMID rollover I-cache maintenance Date: Mon, 9 Sep 2019 14:48:01 +0100 Message-Id: <20190909134807.27978-12-maz@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190909134807.27978-1-maz@kernel.org> References: <20190909134807.27978-1-maz@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190909_064919_552131_73E1A7FD X-CRM114-Status: GOOD ( 11.80 ) X-Spam-Score: 1.0 (+) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (1.0 points) pts rule name description ---- ---------------------- -------------------------------------------------- 1.0 SPF_SOFTFAIL SPF: sender does not match SPF record (softfail) 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 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: Mark Rutland , kvm@vger.kernel.org, Andre Przywara , Eric Auger , James Morse , Zenghui Yu , Alexandru Elisei , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org From: Mark Rutland For VPIPT I-caches, we need I-cache maintenance on VMID rollover to avoid an ABA problem. Consider a single vCPU VM, with a pinned stage-2, running with an idmap VA->IPA and idmap IPA->PA. If we don't do maintenance on rollover: // VMID A Writes insn X to PA 0xF Invalidates PA 0xF (for VMID A) I$ contains [{A,F}->X] [VMID ROLLOVER] // VMID B Writes insn Y to PA 0xF Invalidates PA 0xF (for VMID B) I$ contains [{A,F}->X, {B,F}->Y] [VMID ROLLOVER] // VMID A I$ contains [{A,F}->X, {B,F}->Y] Unexpectedly hits stale I$ line {A,F}->X. However, for PIPT and VIPT I-caches, the VMID doesn't affect lookup or constrain maintenance. Given the VMID doesn't affect PIPT and VIPT I-caches, and given VMID rollover is independent of changes to stage-2 mappings, I-cache maintenance cannot be necessary on VMID rollover for PIPT or VIPT I-caches. This patch removes the maintenance on rollover for VIPT and PIPT I-caches. At the same time, the unnecessary colons are removed from the asm statement to make it more legible. Signed-off-by: Mark Rutland Cc: Christoffer Dall Reviewed-by: James Morse Cc: Julien Thierry Cc: Suzuki K Poulose Cc: kvmarm@lists.cs.columbia.edu Signed-off-by: Marc Zyngier --- arch/arm64/kvm/hyp/tlb.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/hyp/tlb.c b/arch/arm64/kvm/hyp/tlb.c index d49a14497715..c466060b76d6 100644 --- a/arch/arm64/kvm/hyp/tlb.c +++ b/arch/arm64/kvm/hyp/tlb.c @@ -193,6 +193,18 @@ void __hyp_text __kvm_flush_vm_context(void) { dsb(ishst); __tlbi(alle1is); - asm volatile("ic ialluis" : : ); + + /* + * VIPT and PIPT caches are not affected by VMID, so no maintenance + * is necessary across a VMID rollover. + * + * VPIPT caches constrain lookup and maintenance to the active VMID, + * so we need to invalidate lines with a stale VMID to avoid an ABA + * race after multiple rollovers. + * + */ + if (icache_is_vpipt()) + asm volatile("ic ialluis"); + dsb(ish); }