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[209.132.180.67]) by mx.google.com with ESMTP id w10si12442852pgr.136.2018.03.07.23.05.07; Wed, 07 Mar 2018 23:05:21 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935222AbeCHHEV (ORCPT + 99 others); Thu, 8 Mar 2018 02:04:21 -0500 Received: from mx01.hxt-semitech.com.96.203.223.in-addr.arpa ([223.203.96.7]:43201 "EHLO barracuda.hxt-semitech.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S934860AbeCHHEQ (ORCPT ); Thu, 8 Mar 2018 02:04:16 -0500 X-ASG-Debug-ID: 1520492651-093b7e4ca910d00001-xx1T2L Received: from HXTBJIDCEMVIW01.hxtcorp.net ([10.128.0.14]) by barracuda.hxt-semitech.com with ESMTP id RSX4kDqpwnuBAGmB (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 08 Mar 2018 15:04:11 +0800 (CST) X-Barracuda-Envelope-From: shunyong.yang@hxt-semitech.com Received: from y.localdomain (10.5.21.109) by HXTBJIDCEMVIW01.hxtcorp.net (10.128.0.14) with Microsoft SMTP Server (TLS) id 15.0.847.32; Thu, 8 Mar 2018 15:04:10 +0800 From: Shunyong Yang To: CC: , , , , , , , , Shunyong Yang , Joey Zheng Subject: [RFC PATCH] KVM: arm/arm64: vgic: change condition for level interrupt resampling Date: Thu, 8 Mar 2018 15:01:30 +0800 X-ASG-Orig-Subj: [RFC PATCH] KVM: arm/arm64: vgic: change condition for level interrupt resampling Message-ID: <1520492490-7943-1-git-send-email-shunyong.yang@hxt-semitech.com> X-Mailer: git-send-email 1.8.3.1 MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.5.21.109] X-ClientProxiedBy: HXTBJIDCEMVIW01.hxtcorp.net (10.128.0.14) To HXTBJIDCEMVIW01.hxtcorp.net (10.128.0.14) X-Barracuda-Connect: UNKNOWN[10.128.0.14] X-Barracuda-Start-Time: 1520492651 X-Barracuda-Encrypted: ECDHE-RSA-AES256-SHA X-Barracuda-URL: https://192.168.50.101:443/cgi-mod/mark.cgi X-Virus-Scanned: by bsmtpd at hxt-semitech.com X-Barracuda-BRTS-Status: 1 X-Barracuda-Bayes: INNOCENT GLOBAL 0.7508 1.0000 1.7796 X-Barracuda-Spam-Score: 1.78 X-Barracuda-Spam-Status: No, SCORE=1.78 using global scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=1000.0 KILL_LEVEL=9.0 tests= X-Barracuda-Spam-Report: Code version 3.2, rules version 3.2.3.48719 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------------------------- Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When resampling irqfds is enabled, level interrupt should be de-asserted when resampling happens. On page 4-47 of GIC v3 specification IHI0069D, it said, "When the PE acknowledges an SGI, a PPI, or an SPI at the CPU interface, the IRI changes the status of the interrupt to active and pending if: • It is an edge-triggered interrupt, and another edge has been detected since the interrupt was acknowledged. • It is a level-sensitive interrupt, and the level has not been deasserted since the interrupt was acknowledged." GIC v2 specification IHI0048B.b has similar description on page 3-42 for state machine transition. When some VFIO device, like mtty(8250 VFIO mdev emulation driver in samples/vfio-mdev) triggers a level interrupt, the status transition in LR is pending-->active-->active and pending. Then it will wait resampling to de-assert the interrupt. Current design of lr_signals_eoi_mi() will return false if state in LR is not invalid(Inactive). It causes resampling will not happen in mtty case. This will cause interrupt fired continuously to guest even 8250 IIR has no interrupt. When 8250's interrupt is configured in shared mode, it will pass interrupt to other drivers to handle. However, there is no other driver involved. Then, a "nobody cared" kernel complaint occurs. / # cat /dev/ttyS0 [ 4.826836] random: crng init done [ 6.373620] irq 41: nobody cared (try booting with the "irqpoll" option) [ 6.376414] CPU: 0 PID: 1307 Comm: cat Not tainted 4.16.0-rc4 #4 [ 6.378927] Hardware name: linux,dummy-virt (DT) [ 6.380876] Call trace: [ 6.381937] dump_backtrace+0x0/0x180 [ 6.383495] show_stack+0x14/0x1c [ 6.384902] dump_stack+0x90/0xb4 [ 6.386312] __report_bad_irq+0x38/0xe0 [ 6.387944] note_interrupt+0x1f4/0x2b8 [ 6.389568] handle_irq_event_percpu+0x54/0x7c [ 6.391433] handle_irq_event+0x44/0x74 [ 6.393056] handle_fasteoi_irq+0x9c/0x154 [ 6.394784] generic_handle_irq+0x24/0x38 [ 6.396483] __handle_domain_irq+0x60/0xb4 [ 6.398207] gic_handle_irq+0x98/0x1b0 [ 6.399796] el1_irq+0xb0/0x128 [ 6.401138] _raw_spin_unlock_irqrestore+0x18/0x40 [ 6.403149] __setup_irq+0x41c/0x678 [ 6.404669] request_threaded_irq+0xe0/0x190 [ 6.406474] univ8250_setup_irq+0x208/0x234 [ 6.408250] serial8250_do_startup+0x1b4/0x754 [ 6.410123] serial8250_startup+0x20/0x28 [ 6.411826] uart_startup.part.21+0x78/0x144 [ 6.413633] uart_port_activate+0x50/0x68 [ 6.415328] tty_port_open+0x84/0xd4 [ 6.416851] uart_open+0x34/0x44 [ 6.418229] tty_open+0xec/0x3c8 [ 6.419610] chrdev_open+0xb0/0x198 [ 6.421093] do_dentry_open+0x200/0x310 [ 6.422714] vfs_open+0x54/0x84 [ 6.424054] path_openat+0x2dc/0xf04 [ 6.425569] do_filp_open+0x68/0xd8 [ 6.427044] do_sys_open+0x16c/0x224 [ 6.428563] SyS_openat+0x10/0x18 [ 6.429972] el0_svc_naked+0x30/0x34 [ 6.431494] handlers: [ 6.432479] [<000000000e9fb4bb>] serial8250_interrupt [ 6.434597] Disabling IRQ #41 This patch changes the lr state condition in lr_signals_eoi_mi() from invalid(Inactive) to active and pending to avoid this. I am not sure about the original design of the condition of invalid(active). So, This RFC is sent out for comments. Cc: Joey Zheng Signed-off-by: Shunyong Yang --- virt/kvm/arm/vgic/vgic-v2.c | 4 ++-- virt/kvm/arm/vgic/vgic-v3.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/virt/kvm/arm/vgic/vgic-v2.c b/virt/kvm/arm/vgic/vgic-v2.c index e9d840a75e7b..740ee9a5f551 100644 --- a/virt/kvm/arm/vgic/vgic-v2.c +++ b/virt/kvm/arm/vgic/vgic-v2.c @@ -46,8 +46,8 @@ void vgic_v2_set_underflow(struct kvm_vcpu *vcpu) static bool lr_signals_eoi_mi(u32 lr_val) { - return !(lr_val & GICH_LR_STATE) && (lr_val & GICH_LR_EOI) && - !(lr_val & GICH_LR_HW); + return !((lr_val & GICH_LR_STATE) ^ GICH_LR_STATE) && + (lr_val & GICH_LR_EOI) && !(lr_val & GICH_LR_HW); } /* diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c index 6b329414e57a..43111bba7af9 100644 --- a/virt/kvm/arm/vgic/vgic-v3.c +++ b/virt/kvm/arm/vgic/vgic-v3.c @@ -35,8 +35,8 @@ void vgic_v3_set_underflow(struct kvm_vcpu *vcpu) static bool lr_signals_eoi_mi(u64 lr_val) { - return !(lr_val & ICH_LR_STATE) && (lr_val & ICH_LR_EOI) && - !(lr_val & ICH_LR_HW); + return !((lr_val & ICH_LR_STATE) ^ ICH_LR_STATE) && + (lr_val & ICH_LR_EOI) && !(lr_val & ICH_LR_HW); } void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu) -- 1.8.3.1