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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 96819C3F2D2 for ; Fri, 28 Feb 2020 19:16:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6461C246A2 for ; Fri, 28 Feb 2020 19:16:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582917407; bh=BXqh6cgD9aYcDmgFUDG8alw4aMlNGdIq216e0sMu2gM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=A5torGMve+IU6Nxg57y80fgc0vo692JOl93n2RrYkh3XwpxfggRiX1z0ZmhdRsmRl w+jUV6vffyoRVP5EVlKqkoHaoZ0t7KfybHUa1Z6MGKQ7UC39/wf9ACsQISP7lnCY2J o2AC1md2Ql4GrUbP4HVdCHrvR/DH9k9s8tKqboos= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726765AbgB1TQp (ORCPT ); Fri, 28 Feb 2020 14:16:45 -0500 Received: from mail.kernel.org ([198.145.29.99]:49908 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725730AbgB1TQp (ORCPT ); Fri, 28 Feb 2020 14:16:45 -0500 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 5C70A222C2; Fri, 28 Feb 2020 19:16:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582917404; bh=BXqh6cgD9aYcDmgFUDG8alw4aMlNGdIq216e0sMu2gM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=azovb8xMoPOm9v0m36JKUAew5EbZKIOZskp+O30F2ob5dQBTXCBqaC5WreLropVNE GoAajw3AT0SgCfMFadO6XqzXVgsMYURzBXNc+O3uc1HgMkdK1zBUWAkFZh4lONfI8g /wHZmAzy0v2oOUnxfCBGczDdZQULv5EcILGuyIZk= Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1j7l7q-008pqH-Kw; Fri, 28 Feb 2020 19:16:42 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Fri, 28 Feb 2020 19:16:42 +0000 From: Marc Zyngier To: Zenghui Yu Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Lorenzo Pieralisi , Jason Cooper , Robert Richter , Thomas Gleixner , Eric Auger , James Morse , Julien Thierry , Suzuki K Poulose Subject: Re: [PATCH v4 16/20] KVM: arm64: GICv4.1: Allow SGIs to switch between HW and SW interrupts In-Reply-To: <6798eb13-a7e9-2a92-91b2-9b657962ea79@huawei.com> References: <20200214145736.18550-1-maz@kernel.org> <20200214145736.18550-17-maz@kernel.org> <6798eb13-a7e9-2a92-91b2-9b657962ea79@huawei.com> Message-ID: <7aa668a5920b8deb8c2ee2fec3ef69b3@kernel.org> X-Sender: maz@kernel.org User-Agent: Roundcube Webmail/1.3.10 X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: yuzenghui@huawei.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, lorenzo.pieralisi@arm.com, jason@lakedaemon.net, rrichter@marvell.com, tglx@linutronix.de, eric.auger@redhat.com, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Zenghui, On 2020-02-20 03:55, Zenghui Yu wrote: > Hi Marc, > > On 2020/2/14 22:57, Marc Zyngier wrote: >> In order to let a guest buy in the new, active-less SGIs, we >> need to be able to switch between the two modes. >> >> Handle this by stopping all guest activity, transfer the state >> from one mode to the other, and resume the guest. >> >> Signed-off-by: Marc Zyngier > > [...] > >> diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c >> index 1bc09b523486..2c9fc13e2c59 100644 >> --- a/virt/kvm/arm/vgic/vgic-v3.c >> +++ b/virt/kvm/arm/vgic/vgic-v3.c >> @@ -540,6 +540,8 @@ int vgic_v3_map_resources(struct kvm *kvm) >> goto out; >> } >> + if (kvm_vgic_global_state.has_gicv4_1) >> + vgic_v4_configure_vsgis(kvm); >> dist->ready = true; >> out: > > Is there any reason to invoke vgic_v4_configure_vsgis() here? > This is called on the first VCPU run, through kvm_vgic_map_resources(). > Shouldn't the vSGI configuration only driven by a GICD_CTLR.nASSGIreq > writing (from guest, or from userspace maybe)? What I'm trying to catch here is the guest that has been restored with nASSGIreq set. At the moment, we don't do anything on the userspace side, because the vmm could decide to write that particular bit multiple times, and switching between the two modes is expensive (not to mention that all the vcpus may not have been created yet). Moving it to the first run makes all these pitfalls go away (we have the final nASSSGIreq value, and all the vcpus are accounted for). Does this make sense to you? Thanks, M. -- Jazz is not dead. It just smells funny...