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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C7866C433FE for ; Thu, 28 Oct 2021 11:16:57 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 6585161106 for ; Thu, 28 Oct 2021 11:16:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 6585161106 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 15ABF4B1B0; Thu, 28 Oct 2021 07:16:57 -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 jszt8nPxYFMB; Thu, 28 Oct 2021 07:16:55 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 17A1B4B1DB; Thu, 28 Oct 2021 07:16:52 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 04D6E4B1AB for ; Thu, 28 Oct 2021 07:16:50 -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 4MJ7MBYPOILu for ; Thu, 28 Oct 2021 07:16:48 -0400 (EDT) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 755A84B1B0 for ; Thu, 28 Oct 2021 07:16:48 -0400 (EDT) Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D07FB610F8; Thu, 28 Oct 2021 11:16:45 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mg3Ol-002BtD-I6; Thu, 28 Oct 2021 12:16:43 +0100 From: Marc Zyngier To: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH v2 0/5] KVM: arm64: Rework FPSIMD/SVE tracking Date: Thu, 28 Oct 2021 12:16:35 +0100 Message-Id: <20211028111640.3663631-1-maz@kernel.org> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, james.morse@arm.com, suzuki.poulose@arm.com, alexandru.elisei@arm.com, qperret@google.com, will@kernel.org, broonie@kernel.org, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: kernel-team@android.com, Will Deacon , broonie@kernel.org 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 This is v2 of this series aiming at simplifying the FP handling. It recently became apparent that we are mapping each vcpu thread's thread_info structure at EL2 for the sole purpose of checking on the TIF_FOREIGN_FPSTATE flag. Given that this looks like a slightly over-engineered way of sharing a single bit of information, let's move to a slightly more obvious implementation by maintaining a vcpu-private shadow flag that represents the same state. In the same vein, it appears that the code that deals with saving the host SVE state when used by the guest can never run, and that's by construction. This is actually a good thing, because it be guaranteed to explode on nVHE. Let's get rid of it. I also take this opportunity to add what looks like a missing, and nonetheless crucial piece of information to the FPSIMD code regarding the way KVM (ab)uses the TIF_FOREIGN_FPSTATE. Lightly tested on an A53 box with a bunch of paranoia instances running in both host and guests, and more heavily on a FVP to check the SVE behaviour (using the sve-test selftest running in both host and guest at the same time). * From v1 [1]: - New patch getting rid of the host SVE save code - Reworded the documentation update patch [1] https://lore.kernel.org/r/20211021151124.3098113-1-maz@kernel.org Marc Zyngier (5): KVM: arm64: Reorder vcpu flag definitions KVM: arm64: Get rid of host SVE tracking/saving KVM: arm64: Introduce flag shadowing TIF_FOREIGN_FPSTATE KVM: arm64: Stop mapping current thread_info at EL2 arm64/fpsimd: Document the use of TIF_FOREIGN_FPSTATE by KVM arch/arm64/include/asm/kvm_host.h | 29 ++++++++++--------- arch/arm64/kernel/fpsimd.c | 6 +++- arch/arm64/kvm/arm.c | 1 + arch/arm64/kvm/fpsimd.c | 37 ++++++++++--------------- arch/arm64/kvm/hyp/include/hyp/switch.h | 30 +++----------------- arch/arm64/kvm/hyp/nvhe/switch.c | 1 - arch/arm64/kvm/hyp/vhe/switch.c | 1 - 7 files changed, 38 insertions(+), 67 deletions(-) -- 2.30.2 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm