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 48E22C433F5 for ; Wed, 20 Oct 2021 13:52:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2FE7D6103D for ; Wed, 20 Oct 2021 13:52:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230031AbhJTNys (ORCPT ); Wed, 20 Oct 2021 09:54:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:50128 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230190AbhJTNys (ORCPT ); Wed, 20 Oct 2021 09:54:48 -0400 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 097B161052; Wed, 20 Oct 2021 13:52:34 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) 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 1mdC19-000RjV-SP; Wed, 20 Oct 2021 14:52:31 +0100 Date: Wed, 20 Oct 2021 14:52:31 +0100 Message-ID: <874k9bdcrk.wl-maz@kernel.org> From: Marc Zyngier To: Hikaru Nishida Cc: linux-kernel@vger.kernel.org, dme@dme.org, tglx@linutronix.de, mlevitsk@redhat.com, linux@roeck-us.net, pbonzini@redhat.com, vkuznets@redhat.com, will@kernel.org, suleiman@google.com, senozhatsky@google.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Dave Hansen , Geert Uytterhoeven , "H. Peter Anvin" , Ingo Molnar , Ingo Molnar , Jim Mattson , Joerg Roedel , John Stultz , Jonathan Corbet , Juergen Gross , Kees Cook , Lai Jiangshan , Linus Walleij , Peter Zijlstra , Sean Christopherson , Stephen Boyd , Wanpeng Li , kvm@vger.kernel.org, linux-doc@vger.kernel.org, x86@kernel.org Subject: Re: [RFC PATCH v3 0/5] x86/kvm: Virtual suspend time injection support In-Reply-To: <20211020120431.776494-1-hikalium@chromium.org> References: <20211020120431.776494-1-hikalium@chromium.org> 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: 185.219.108.64 X-SA-Exim-Rcpt-To: hikalium@chromium.org, linux-kernel@vger.kernel.org, dme@dme.org, tglx@linutronix.de, mlevitsk@redhat.com, linux@roeck-us.net, pbonzini@redhat.com, vkuznets@redhat.com, will@kernel.org, suleiman@google.com, senozhatsky@google.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, luto@kernel.org, arnd@arndb.de, bp@alien8.de, dave.hansen@linux.intel.com, geert@linux-m68k.org, hpa@zytor.com, mingo@kernel.org, mingo@redhat.com, jmattson@google.com, joro@8bytes.org, john.stultz@linaro.org, corbet@lwn.net, jgross@suse.com, keescook@chromium.org, laijs@linux.alibaba.com, linus.walleij@linaro.org, peterz@infradead.org, seanjc@google.com, sboyd@kernel.org, wanpengli@tencent.com, kvm@vger.kernel.org, linux-doc@vger.kernel.org, x86@kernel.org 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: linux-doc@vger.kernel.org Hi Hikaru, On Wed, 20 Oct 2021 13:04:25 +0100, Hikaru Nishida wrote: > > > Hi, > > This patch series adds virtual suspend time injection support to KVM. > It is an updated version of the following series: > v2: > https://lore.kernel.org/kvm/20210806100710.2425336-1-hikalium@chromium.org/ > v1: > https://lore.kernel.org/kvm/20210426090644.2218834-1-hikalium@chromium.org/ > > Please take a look again. > > To kvm/arm64 folks: > I'm going to implement this mechanism to ARM64 as well but not > sure which function should be used to make an IRQ (like kvm_apic_set_irq > in x86) and if it is okay to use kvm_gfn_to_hva_cache / > kvm_write_guest_cached for sharing the suspend duration. Before we discuss interrupt injection, I want to understand what this is doing, and how this is doing it. And more precisely, I want to find out how you solve the various problems described by Thomas here [1]. Assuming you solve these, you should model the guest memory access similarly to what we do for stolen time. As for injecting an interrupt, why can't this be a userspace thing? Thanks, M. [1] https://lore.kernel.org/all/871r557jls.ffs@tglx -- Without deviation from the norm, progress is not possible.