From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755559AbeCHP3a (ORCPT ); Thu, 8 Mar 2018 10:29:30 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:56958 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752060AbeCHP32 (ORCPT ); Thu, 8 Mar 2018 10:29:28 -0500 Subject: =?UTF-8?B?UmU6IFvmraTpgq7ku7blj6/og73lrZjlnKjpo47pmaldIFJlOiBbUkZD?= =?UTF-8?Q?_PATCH]_KVM:_arm/arm64:_vgic:_change_condition_for_level_interrup?= =?UTF-8?Q?t_resampling?= To: "Yang, Shunyong" , "cdall@kernel.org" References: <1520492490-7943-1-git-send-email-shunyong.yang@hxt-semitech.com> <9b3763f2-1dfa-5506-d7f2-93389647111c@redhat.com> <1520501495.2583.19.camel@hxt-semitech.com> Cc: "linux-kernel@vger.kernel.org" , "ard.biesheuvel@linaro.org" , "kvmarm@lists.cs.columbia.edu" , "Zheng, Joey" , "will.deacon@arm.com" , "linux-arm-kernel@lists.infradead.org" , "david.daney@cavium.com" , "marc.zyngier@arm.com" From: Auger Eric Message-ID: <8c27ce1a-908b-3be9-7e10-d2151c48a918@redhat.com> Date: Thu, 8 Mar 2018 16:29:23 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <1520501495.2583.19.camel@hxt-semitech.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Shunyong, On 08/03/18 10:31, Yang, Shunyong wrote: > Hi, Eric, > > First, please let me change Christoffer's email to cdall@kernel.org. I > add more information about my test below, please check. > > On Thu, 2018-03-08 at 09:57 +0100, Auger Eric wrote: >> Hi, >> >> On 08/03/18 08:01, Shunyong Yang wrote: >>> >>> 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); >> >> In general don't we have this state transition >> >> inactive -> pending -> pending + active (1) -> active -> inactive. >> >> In that case won't we lower the virt irq level when folding the LR on >> Pending + Active state, which is not was we want? >> >> Thanks >> >> Eric > > In current code, in my test, when I output LR value of the mtty IRQ 41 > (hwirq = 36) in vgic_v3_fold_lr_state(). The LR's transition starts > like following, > > 0-->50a0020000000024-->90a0020000000024-->d0a0020000000024 > > That is inactive-->pending-->active-->pending + active. Yes sorry I did a big mixture of virt line level and LR pending state. I had below case in mind: P -> guest IAR -> A -> exit/entry -> P+A -> exit in which case you shouldn't call the resampler. Thanks Eric > Then it keep running cyclic pending-->active-->pending + active. > > The level interrupt de-assert should happen in following code > /* Notify fds when the guest EOI'ed a level-triggered IRQ */ > if (lr_signals_eoi_mi(val) && vgic_valid_spi(vcpu->kvm, intid)) > kvm_notify_acked_irq(vcpu->kvm, 0, > intid - VGIC_NR_PRIVATE_IRQS); > > But as addressed in commit message, lr_signals_eoi_mi() will return > false if state in LR is not invalid(inactive), so it has no chance to > de-assert the level interrupt in my test. > > Thanks. > Shunyong. > >> >>> >>> } >>> >>> void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu) >>> From mboxrd@z Thu Jan 1 00:00:00 1970 From: eric.auger@redhat.com (Auger Eric) Date: Thu, 8 Mar 2018 16:29:23 +0100 Subject: =?UTF-8?B?UmU6IFvmraTpgq7ku7blj6/og73lrZjlnKjpo47pmaldIFJlOiBbUkZD?= =?UTF-8?Q?_PATCH]_KVM:_arm/arm64:_vgic:_change_condition_for_level_interrup?= =?UTF-8?Q?t_resampling?= In-Reply-To: <1520501495.2583.19.camel@hxt-semitech.com> References: <1520492490-7943-1-git-send-email-shunyong.yang@hxt-semitech.com> <9b3763f2-1dfa-5506-d7f2-93389647111c@redhat.com> <1520501495.2583.19.camel@hxt-semitech.com> Message-ID: <8c27ce1a-908b-3be9-7e10-d2151c48a918@redhat.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Shunyong, On 08/03/18 10:31, Yang, Shunyong wrote: > Hi, Eric, > > First, please let me change Christoffer's email to cdall at kernel.org. I > add more information about my test below, please check. > > On Thu, 2018-03-08 at 09:57 +0100, Auger Eric wrote: >> Hi, >> >> On 08/03/18 08:01, Shunyong Yang wrote: >>> >>> 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); >> >> In general don't we have this state transition >> >> inactive -> pending -> pending + active (1) -> active -> inactive. >> >> In that case won't we lower the virt irq level when folding the LR on >> Pending + Active state, which is not was we want? >> >> Thanks >> >> Eric > > In current code, in my test, when I output LR value of the mtty IRQ 41 > (hwirq = 36) in vgic_v3_fold_lr_state(). The LR's transition starts > like following, > > 0-->50a0020000000024-->90a0020000000024-->d0a0020000000024 > > That is inactive-->pending-->active-->pending + active. Yes sorry I did a big mixture of virt line level and LR pending state. I had below case in mind: P -> guest IAR -> A -> exit/entry -> P+A -> exit in which case you shouldn't call the resampler. Thanks Eric > Then it keep running cyclic pending-->active-->pending + active. > > The level interrupt de-assert should happen in following code > /* Notify fds when the guest EOI'ed a level-triggered IRQ */ > if (lr_signals_eoi_mi(val) && vgic_valid_spi(vcpu->kvm, intid)) > kvm_notify_acked_irq(vcpu->kvm, 0, > intid - VGIC_NR_PRIVATE_IRQS); > > But as addressed in commit message, lr_signals_eoi_mi() will return > false if state in LR is not invalid(inactive), so it has no chance to > de-assert the level interrupt in my test. > > Thanks. > Shunyong. > >> >>> >>> } >>> >>> void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu) >>>