linux-kernel - RE: [PATCH v3 6/6] PCI: hv: fix 2 hang issues in hv_compose_msi

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Message-ID: <DM5PR2101MB1030B09B080E5854B0E7B9A9DCD90@DM5PR2101MB1030.namprd21.prod.outlook.com>
Date:   Tue, 6 Mar 2018 18:32:29 +0000
From:   "Michael Kelley (EOSG)" <Michael.H.Kelley@...rosoft.com>
To:     Dexuan Cui <decui@...rosoft.com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        KY Srinivasan <kys@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "olaf@...fle.de" <olaf@...fle.de>,
        "apw@...onical.com" <apw@...onical.com>,
        "jasowang@...hat.com" <jasowang@...hat.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "driverdev-devel@...uxdriverproject.org" 
        <driverdev-devel@...uxdriverproject.org>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>,
        "marcelo.cerri@...onical.com" <marcelo.cerri@...onical.com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Jack Morgenstein <jackm@...lanox.com>
Subject: RE: [PATCH v3 6/6] PCI: hv: fix 2 hang issues in hv_compose_msi_msg()

> -----Original Message-----
> From: Dexuan Cui
> Sent: Tuesday, March 6, 2018 10:22 AM
> To: bhelgaas@...gle.com; linux-pci@...r.kernel.org; KY Srinivasan <kys@...rosoft.com>;
> Stephen Hemminger <sthemmin@...rosoft.com>; olaf@...fle.de; apw@...onical.com;
> jasowang@...hat.com
> Cc: linux-kernel@...r.kernel.org; driverdev-devel@...uxdriverproject.org; Haiyang Zhang
> <haiyangz@...rosoft.com>; vkuznets@...hat.com; marcelo.cerri@...onical.com; Michael
> Kelley (EOSG) <Michael.H.Kelley@...rosoft.com>; Dexuan Cui <decui@...rosoft.com>;
> stable@...r.kernel.org; Jack Morgenstein <jackm@...lanox.com>
> Subject: [PATCH v3 6/6] PCI: hv: fix 2 hang issues in hv_compose_msi_msg()
> 
> 1. With the patch "x86/vector/msi: Switch to global reservation mode"
> (4900be8360), the recent v4.15 and newer kernels always hang for 1-vCPU
> Hyper-V VM with SR-IOV. This is because when we reach hv_compose_msi_msg()
> by request_irq()  -> request_threaded_irq() -> __setup_irq()->irq_startup()
>  -> __irq_startup() -> irq_domain_activate_irq() -> ... ->
> msi_domain_activate() -> ... -> hv_compose_msi_msg(), local irq is
> disabled in __setup_irq().
> 
> Fix this by polling the channel.
> 
> 2. If the host is ejecting the VF device before we reach
> hv_compose_msi_msg(), in a UP VM, we can hang in hv_compose_msi_msg()
> forever, because at this time the host doesn't respond to the
> CREATE_INTERRUPT request. This issue also happens to old kernels like
> v4.14, v4.13, etc.
> 
> Fix this by polling the channel for the PCI_EJECT message and
> hpdev->state, and by checking the PCI vendor ID.
> 
> Note: actually the above issues also happen to a SMP VM, if
> "hbus->hdev->channel->target_cpu == smp_processor_id()" is true.
> 
> Signed-off-by: Dexuan Cui <decui@...rosoft.com>
> Tested-by: Adrian Suhov <v-adsuho@...rosoft.com>
> Tested-by: Chris Valean <v-chvale@...rosoft.com>
> Cc: stable@...r.kernel.org
> Cc: Stephen Hemminger <sthemmin@...rosoft.com>
> Cc: K. Y. Srinivasan <kys@...rosoft.com>
> Cc: Vitaly Kuznetsov <vkuznets@...hat.com>
> Cc: Jack Morgenstein <jackm@...lanox.com>
> ---
>  drivers/pci/host/pci-hyperv.c | 58 ++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 57 insertions(+), 1 deletion(-)
> 

Reviewed-by: Michael Kelley <mikelley@...rosoft.com>