From patchwork Tue Mar 16 17:46:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 12143353 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=-17.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 F0EC2C4332E for ; Tue, 16 Mar 2021 17:47:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CC5796512A for ; Tue, 16 Mar 2021 17:47:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239324AbhCPRrG (ORCPT ); Tue, 16 Mar 2021 13:47:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:39990 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239225AbhCPRqm (ORCPT ); Tue, 16 Mar 2021 13:46:42 -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 545396512A; Tue, 16 Mar 2021 17:46:42 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1lMDmC-0021ao-EX; Tue, 16 Mar 2021 17:46:40 +0000 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu Cc: James Morse , Julien Thierry , Suzuki K Poulose , Alexandru Elisei , Eric Auger , Hector Martin , Mark Rutland , kernel-team@android.com Subject: [PATCH 03/11] KVM: arm64: vgic: Be tolerant to the lack of maintenance interrupt Date: Tue, 16 Mar 2021 17:46:08 +0000 Message-Id: <20210316174617.173033-4-maz@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210316174617.173033-1-maz@kernel.org> References: <20210316174617.173033-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, alexandru.elisei@arm.com, eric.auger@redhat.com, marcan@marcan.st, mark.rutland@arm.com, kernel-team@android.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 As it turns out, not all the interrupt controllers are able to expose a vGIC maintenance interrupt as a distrete signal. And to be fair, it doesn't really matter as all we require is for *something* to kick us out of guest mode out way or another. On systems that do not expose a maintenance interrupt as such, there are two outcomes: - either the virtual CPUIF does generate an interrupt, and by the time we are back to the host the interrupt will have long been disabled (as we set ICH_HCR_EL2.EN to 0 on exit). In this case, interrupt latency is as good as it gets. - or some other event (physical timer) will take us out of the guest anyway, and the only drawback is a bad interrupt latency. So let's be tolerant to the lack of maintenance interrupt, and just let the user know that their mileage may vary... Signed-off-by: Marc Zyngier --- arch/arm64/kvm/vgic/vgic-init.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c index 9b491263f5f7..00c75495fd0c 100644 --- a/arch/arm64/kvm/vgic/vgic-init.c +++ b/arch/arm64/kvm/vgic/vgic-init.c @@ -521,11 +521,6 @@ int kvm_vgic_hyp_init(void) if (!gic_kvm_info) return -ENODEV; - if (!gic_kvm_info->maint_irq) { - kvm_err("No vgic maintenance irq\n"); - return -ENXIO; - } - switch (gic_kvm_info->type) { case GIC_V2: ret = vgic_v2_probe(gic_kvm_info); @@ -549,6 +544,11 @@ int kvm_vgic_hyp_init(void) if (ret) return ret; + if (!kvm_vgic_global_state.maint_irq) { + kvm_err("No maintenance interrupt available, fingers crossed...\n"); + return 0; + } + ret = request_percpu_irq(kvm_vgic_global_state.maint_irq, vgic_maintenance_handler, "vgic", kvm_get_running_vcpus());