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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 C466CC31E5B for ; Tue, 18 Jun 2019 15:18:28 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 82206213F2 for ; Tue, 18 Jun 2019 15:18:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 82206213F2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 3A79C4A528; Tue, 18 Jun 2019 11:18:28 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id NFCxYcAnag5B; Tue, 18 Jun 2019 11:18:27 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 021944A52A; Tue, 18 Jun 2019 11:18:27 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 4F77A4A47E for ; Tue, 18 Jun 2019 11:18:26 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id RpHmt1pNd6Fa for ; Tue, 18 Jun 2019 11:18:25 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mm01.cs.columbia.edu (Postfix) with ESMTP id CC9784A50D for ; Tue, 18 Jun 2019 11:18:24 -0400 (EDT) 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 897912B; Tue, 18 Jun 2019 08:18:24 -0700 (PDT) Received: from eglon.cambridge.arm.com (eglon.cambridge.arm.com [10.1.196.105]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A0C1E3F718; Tue, 18 Jun 2019 08:18:23 -0700 (PDT) From: James Morse To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu Subject: [PATCH v3 2/2] KVM: arm64: Skip more of the SError vaxorcism Date: Tue, 18 Jun 2019 16:18:09 +0100 Message-Id: <20190618151809.259038-3-james.morse@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190618151809.259038-1-james.morse@arm.com> References: <20190618151809.259038-1-james.morse@arm.com> MIME-Version: 1.0 Cc: Marc Zyngier X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu During __guest_exit() we need to consume any SError left pending by the guest so it doesn't contaminate the host. With v8.2 we use the ESB-instruction. For systems without v8.2, we use dsb+isb and unmask SError. We do this on every guest exit. Use the same dsb+isr_el1 trick, this lets us know if an SError is pending after the dsb, allowing us to skip the isb and self-synchronising PSTATE write if its not. This means SError remains masked during KVM's world-switch, so any SError that occurs during this time is reported by the host, instead of causing a hyp-panic. As we're benchmarking this code lets polish the layout. If you give gcc likely()/unlikely() hints in an if() condition, it shuffles the generated assembly so that the likely case is immediately after the branch. Lets do the same here. Signed-off-by: James Morse Changes since v2: * Added isb after the dsb to prevent an early read --- arch/arm64/kvm/hyp/entry.S | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S index 017ec4189a08..269e7b2da1fd 100644 --- a/arch/arm64/kvm/hyp/entry.S +++ b/arch/arm64/kvm/hyp/entry.S @@ -162,8 +162,16 @@ alternative_if ARM64_HAS_RAS_EXTN orr x0, x0, #(1<