From patchwork Mon Nov 23 06:54:06 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shenming Lu X-Patchwork-Id: 11924447 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 C1FC8C63697 for ; Mon, 23 Nov 2020 06:55:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 74C6520888 for ; Mon, 23 Nov 2020 06:55:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727769AbgKWGyy (ORCPT ); Mon, 23 Nov 2020 01:54:54 -0500 Received: from szxga06-in.huawei.com ([45.249.212.32]:7964 "EHLO szxga06-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725275AbgKWGyy (ORCPT ); Mon, 23 Nov 2020 01:54:54 -0500 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga06-in.huawei.com (SkyGuard) with ESMTP id 4CfdDn12VvzhgH2; Mon, 23 Nov 2020 14:54:33 +0800 (CST) Received: from DESKTOP-7FEPK9S.china.huawei.com (10.174.187.74) by DGGEMS405-HUB.china.huawei.com (10.3.19.205) with Microsoft SMTP Server id 14.3.487.0; Mon, 23 Nov 2020 14:54:38 +0800 From: Shenming Lu To: Marc Zyngier , James Morse , "Julien Thierry" , Suzuki K Poulose , Eric Auger , , , , , Christoffer Dall CC: Alex Williamson , Kirti Wankhede , Cornelia Huck , Neo Jia , , , Subject: [RFC PATCH v1 0/4] KVM: arm64: Add VLPI migration support on GICv4.1 Date: Mon, 23 Nov 2020 14:54:06 +0800 Message-ID: <20201123065410.1915-1-lushenming@huawei.com> X-Mailer: git-send-email 2.27.0.windows.1 MIME-Version: 1.0 X-Originating-IP: [10.174.187.74] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org In GICv4.1, migration has been supported except for (directly-injected) VLPI. And GICv4.1 spec explicitly gives a way to get the VLPI's pending state (which was crucially missing in GICv4.0). So we make VLPI migration capable on GICv4.1 in this patch set. In order to support VLPI migration, we need to save and restore all required configuration information and pending states of VLPIs. But in fact, the configuration information of VLPIs has already been saved (or will be reallocated on the dst host...) in vgic(kvm) migration. So we only have to migrate the pending states of VLPIs specially. Below is the related workflow in migration. On the save path: In migration completion: pause all vCPUs | call each VM state change handler: pause other devices (just keep from sending interrupts, and such as VFIO migration protocol has already realized it [1]) | flush ITS tables into guest RAM | flush RDIST pending tables (also flush VLPI state here) | ... On the resume path: load each device's state: restore ITS tables (include pending tables) from guest RAM | for other (PCI) devices (paused), if configured to have VLPIs, establish the forwarding paths of their VLPIs (and transfer the pending states from kvm's vgic to VPT here) Yet TODO: - For some reason, such as for VFIO PCI devices, there may be repeated resettings of HW VLPI configuration in load_state, resulting in the loss of pending state. A very intuitive solution is to retrieve the pending state in unset_forwarding (and this should be so regardless of migration). But at normal run time, this function may be called when all devices are running, in which case the unmapping of VPE is not allowed. It seems to be an almost insoluble bug... There are other possible solutions as follows: 1) avoid unset_forwarding being called from QEMU in resuming (simply allocate all needed vectors first), which is more reasonable and efficient. 2) add a new dedicated interface to transfer these pending states to HW in GIC VM state change handler corresponding to save_pending_tables. ... Any comments and suggestions are very welcome. Besides, we have tested this series in VFIO migration, and nothing else goes wrong (with two issues committed [2][3]). Links: [1] vfio: UAPI for migration interface for device state: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ commit/?id=a8a24f3f6e38103b77cf399c38eb54e1219d00d6 [2] vfio: Move the saving of the config space to the right place in VFIO migration: https://patchwork.ozlabs.org/patch/1400246/ [3] vfio: Set the priority of VFIO VM state change handler explicitly: https://patchwork.ozlabs.org/patch/1401280/ Shenming Lu (2): KVM: arm64: GICv4.1: Try to save hw pending state in save_pending_tables KVM: arm64: GICv4.1: Give a chance to save VLPI's pending state Zenghui Yu (2): irqchip/gic-v4.1: Plumb get_irqchip_state VLPI callback KVM: arm64: GICv4.1: Restore VLPI's pending state to physical side .../virt/kvm/devices/arm-vgic-its.rst | 2 +- arch/arm64/kvm/vgic/vgic-its.c | 6 +- arch/arm64/kvm/vgic/vgic-v3.c | 62 +++++++++++++++++-- arch/arm64/kvm/vgic/vgic-v4.c | 12 ++++ drivers/irqchip/irq-gic-v3-its.c | 38 ++++++++++++ 5 files changed, 110 insertions(+), 10 deletions(-)