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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id BB923C02198 for ; Mon, 10 Feb 2025 20:07:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=perwAGRgEJNnspfpmsr22K3usox8CU4TWBBB5uIhoSI=; b=J8a78F8EKqqjGOmCyiL8o5qFaI 4YvopJ5t56QzcvLU9uewYuRsaikREUtun8LbptnrwPYxAt5y9lJhhR8VfyKkxLyH6J0G47SBYidvx G8gO/meYWjgMN3xmGOAGEpufUTYnQNjZSSHgQ9IJiYFIBzH2sDOh8amEFd5HVosIuDaoxwJ1+vTrV k854laIxtQzglccmpFNn7m00PvCz7ncgDND2mGkiqjeUQY4keWc3cs2gZPI8FRDR1ZO8m5L0z0Ibv Kf9wKo4F5LexdRCbjXSTCmP663JtCwyiNDJRvs3diA/GsqSe8uA4IxXeuBEhfX8XG3Is3Wl+a4g4l k4WDHsNg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tha3Y-00000001Gn8-0jmD; Mon, 10 Feb 2025 20:07:00 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1thZzt-00000001GLG-2MAD for linux-arm-kernel@lists.infradead.org; Mon, 10 Feb 2025 20:03:14 +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 5F7551477; Mon, 10 Feb 2025 12:03:34 -0800 (PST) Received: from J2N7QTR9R3 (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 496553F58B; Mon, 10 Feb 2025 12:03:10 -0800 (PST) Date: Mon, 10 Feb 2025 20:03:04 +0000 From: Mark Rutland To: Will Deacon Cc: linux-arm-kernel@lists.infradead.org, broonie@kernel.org, catalin.marinas@arm.com, eauger@redhat.com, eric.auger@redhat.com, fweimer@redhat.com, jeremy.linton@arm.com, maz@kernel.org, oliver.upton@linux.dev, pbonzini@redhat.com, stable@vger.kernel.org, tabba@google.com, wilco.dijkstra@arm.com Subject: Re: [PATCH v2 2/8] KVM: arm64: Remove host FPSIMD saving for non-protected KVM Message-ID: References: <20250206141102.954688-1-mark.rutland@arm.com> <20250206141102.954688-3-mark.rutland@arm.com> <20250210161242.GC7568@willie-the-truck> <20250210180637.GA7926@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250210180637.GA7926@willie-the-truck> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250210_120313_642401_6221B387 X-CRM114-Status: GOOD ( 18.13 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Feb 10, 2025 at 06:06:38PM +0000, Will Deacon wrote: > On Mon, Feb 10, 2025 at 04:59:56PM +0000, Mark Rutland wrote: > > On Mon, Feb 10, 2025 at 04:12:43PM +0000, Will Deacon wrote: > > > On Thu, Feb 06, 2025 at 02:10:56PM +0000, Mark Rutland wrote: > > | static inline bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code) > > | { > > | ... > > | > > | /* Valid trap */ > > | > > | /* > > | * Enable everything EL2 might need to save/restore state. > > | * Maybe each of the bits should depend on system_has_xxx() > > | */ > > | cpacr_clear_set(0, CPACR_EL1_FPEN | CPACR_EL1_ZEN | CPACR_EL1_SMEN */ > > | isb(); > > | > > | ... > > | > > | /* Write out the host state if it's in the registers */ > > | if (is_protected_kvm_enabled() && host_owns_fp_regs()) > > | kvm_hyp_save_fpsimd_host(vcpu); > > | > > | /* Restore guest state */ > > | > > | ... > > | > > | /* > > | * Enable traps for the VCPU. The ERET will cause the traps to > > | * take effect in the guest, so no ISB is necessary. > > | */ > > | cpacr_guest = CPACR_EL1_FPEN; > > | if (vcpu_has_sve(vcpu)) > > | cpacr_guest |= CPACR_EL1_ZEN; > > | if (vcpu_has_sme(vcpu)) // whenever we add this > > | cpacr_guest |= CPACR_EL1_SMEN; > > | cpacr_clear_set(CPACR_EL1_FPEN | CPACR_EL1_ZEN | CPACR_EL1_SMEN, > > | cpacr_guest); > > | > > | return true; > > | } > > > > ... where we'd still have the CPACR write to re-enable traps, but it'd > > be unconditional, and wouldn't need an extra ISB. > > > > If that makes sense to you, I can go spin that as a subsequent cleanup > > atop this series. > > That looks very clean, yes please! Don't forget to drop the part from > kvm_hyp_save_fpsimd_host() too. Yep, that was the idea! To avoid confusion: I've sent out v3 of this series *without* the change, and I'll prepare that as a follow-up. Mark.