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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9B7DAC6FA8B for ; Wed, 21 Sep 2022 17:04:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230403AbiIURET (ORCPT ); Wed, 21 Sep 2022 13:04:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55132 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230289AbiIURER (ORCPT ); Wed, 21 Sep 2022 13:04:17 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0EEC365675; Wed, 21 Sep 2022 10:04:14 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 65542B831DC; Wed, 21 Sep 2022 17:04:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 08E08C433D6; Wed, 21 Sep 2022 17:04:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1663779852; bh=RGY/+E7y3fbSpPzUjXEy0bH0yclZbLHNIfDEwoLwz8c=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=h1mFj9Yod+ASHDM4fYHsnrVhI5Iriw9xJf3fgedkVkVl3qL4C4PXFivNP2Hn4MR+X 5SIOSWvAH8AshHnMcGDkd3gQceCuxMlkuRCscWa5WRywubAmRpB7J5P0v7fVI8dPlA Ue9OLTQ0A/kaYyfs2NBU4/yRvRWQ0lD2bfoTTo05H5EPIym0ztG3EZqvf2gf5t8jtX /uk3y9phkG9pyojXjCdY4fOvwBGYNKb0D6FLTv2WsG8hjyPzCxsYCVXzgjCn9psirh 0drecuIvIi3XEW9er5MQ93cRRcvF2zQ8LTRpAl2mjJcwA2k7UsRYpDfRYbaedA+5i8 Qdgrhj/0G6q9g== Received: from 185-176-101-241.host.sccbroadband.ie ([185.176.101.241] helo=wait-a-minute.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1ob38r-00Bj60-Kx; Wed, 21 Sep 2022 18:04:09 +0100 Date: Wed, 21 Sep 2022 18:04:07 +0100 Message-ID: <87r104k6bc.wl-maz@kernel.org> From: Marc Zyngier To: Alexey Kardashevskiy Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm-riscv@lists.infradead.org, Paolo Bonzini , Anup Patel , kvm-ppc@vger.kernel.org, Nicholas Piggin Subject: Re: [PATCH kernel v2] KVM: PPC: Make KVM_CAP_IRQFD_RESAMPLE support platform dependent In-Reply-To: <02490d2a-5e89-f342-f5b3-386406ffb2ea@ozlabs.ru> References: <20220920125143.28009-1-aik@ozlabs.ru> <874jx2kp02.wl-maz@kernel.org> <02490d2a-5e89-f342-f5b3-386406ffb2ea@ozlabs.ru> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.176.101.241 X-SA-Exim-Rcpt-To: aik@ozlabs.ru, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm-riscv@lists.infradead.org, pbonzini@redhat.com, anup@brainfault.org, kvm-ppc@vger.kernel.org, npiggin@gmail.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, 20 Sep 2022 22:46:21 +0100, Alexey Kardashevskiy wrote: > > > > On 21/09/2022 02:08, Marc Zyngier wr > ote: > > On Tue, 20 Sep 2022 13:51:43 +0100, > > Alexey Kardashevskiy wrote: > >> > >> When introduced, IRQFD resampling worked on POWER8 with XICS. However > >> KVM on POWER9 has never implemented it - the compatibility mode code > >> ("XICS-on-XIVE") misses the kvm_notify_acked_irq() call and the native > >> XIVE mode does not handle INTx in KVM at all. > >> > >> This moved the capability support advertising to platforms and stops > >> advertising it on XIVE, i.e. POWER9 and later. > >> > >> Signed-off-by: Alexey Kardashevskiy > >> Acked-by: Nicholas Piggin > >> [For KVM RISC-V] > >> Acked-by: Anup Patel > >> --- > >> Changes: > >> v2: > >> * removed ifdef for ARM64. > > > > The same argument applies to both x86 and s390, which do select > > HAVE_KVM_IRQFD from the KVM config option. Only power allows this > > option to be selected depending on the underlying interrupt controller > > emulation. > > > > As for riscv and mips, they don't select HAVE_KVM_IRQFD, and this > > isn't a user-selectable option. So why do they get patched at all? > > Before the patch, the capability was advertised on those, with your > proposal it will stop. No, they were never advertised, since none of these architectures select CONFIG_HAVE_KVM_IRQFD, and this option is not selectable by the user. > Which is a change in behavior which some may > say requires a separate patch (like, one per platform). I am > definitely overthinking it though and you are right. Well, either there is no change in behaviour (and therefore I am right), or there is one (and I am wrong). M. -- Without deviation from the norm, progress is not possible.