From patchwork Tue Aug 6 15:57:37 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 11079263 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 02A7E1399 for ; Tue, 6 Aug 2019 15:57:54 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E5873284E8 for ; Tue, 6 Aug 2019 15:57:53 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D8E5F28622; Tue, 6 Aug 2019 15:57:53 +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=ham 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 580E2284E8 for ; Tue, 6 Aug 2019 15:57:53 +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:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: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:In-Reply-To: References:List-Owner; bh=u0p67WzW6Ea0QOM59T5mF2+Ebv8t9DNpqkcG/0gie0s=; b=MCz fb0KEM4Rk7L/q6eu5AkOb0e7kIQ8z3nHyWlbjDvY3yML89Ddz2xdRN4wklDJHykWzGBCjX334pvcK SW7DV93+0Q065P6mzpbHSgRk0GXgTsbA7rMoE7bal24ZM7g9hyoqshHU8FortFBHk9y2gCu7iAuEs PtggZafRVwK1sY4Pndw/Rh71vV5iqoLmmeXYuBbRNSBWxSGK9Lqkih7rQgZ6akto/J7PQSCoJeqje Qt5/2jV+NG7wCc8R+PzdOBYL8ot754tH7WANggVBgJZ78hmuN0L7UYjzNW9msDKoNsuRiP4NJjVtZ qONAJjvEX9SLbmJd9Qwnzkr8RsuqA4g==; 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 1hv1qS-0004fS-4y; Tue, 06 Aug 2019 15:57:52 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hv1qP-0004ez-NA for linux-arm-kernel@lists.infradead.org; Tue, 06 Aug 2019 15:57:51 +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 E1D65344; Tue, 6 Aug 2019 08:57:48 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id C30353F575; Tue, 6 Aug 2019 08:57:47 -0700 (PDT) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] arm64/kvm: remove VMID rollover I-cache maintenance Date: Tue, 6 Aug 2019 16:57:37 +0100 Message-Id: <20190806155737.39307-1-mark.rutland@arm.com> X-Mailer: git-send-email 2.11.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190806_085749_804293_23B0EC67 X-CRM114-Status: GOOD ( 10.78 ) 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 , Suzuki K Poulose , Marc Zyngier , Christoffer Dall , James Morse , kvmarm@lists.cs.columbia.edu, Julien Thierry MIME-Version: 1.0 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 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 Cc: James Morse Cc: Julien Thierry Cc: Marc Zyngier Cc: Suzuki K Poulose Cc: kvmarm@lists.cs.columbia.edu Reviewed-by: James Morse --- 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); }