Message-ID: <93de5e89-cab3-fa0d-e534-7e6efddf8468@intel.com>
Date:   Fri, 17 Mar 2023 09:48:14 -0700
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Subject: Re: [RFC PATCH 0/8] vfio/pci: Support dynamic allocation of MSI-X
 interrupts
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To:     "Tian, Kevin" <kevin.tian@intel.com>,
        Alex Williamson <alex.williamson@redhat.com>
CC:     "jgg@nvidia.com" <jgg@nvidia.com>,
        "yishaih@nvidia.com" <yishaih@nvidia.com>,
        "shameerali.kolothum.thodi@huawei.com" 
        <shameerali.kolothum.thodi@huawei.com>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "darwi@linutronix.de" <darwi@linutronix.de>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "Jiang, Dave" <dave.jiang@intel.com>,
        "Liu, Jing2" <jing2.liu@intel.com>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        "Yu, Fenghua" <fenghua.yu@intel.com>,
        "tom.zanussi@linux.intel.com" <tom.zanussi@linux.intel.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <cover.1678911529.git.reinette.chatre@intel.com>
 <20230316155646.07ae266f.alex.williamson@redhat.com>
 <4d72821b-36a2-70c9-ee58-f7a21b13510f@intel.com>
 <BN9PR11MB5276C1DE988777A97FC5D2A78CBC9@BN9PR11MB5276.namprd11.prod.outlook.com>
From:   Reinette Chatre <reinette.chatre@intel.com>
In-Reply-To: <BN9PR11MB5276C1DE988777A97FC5D2A78CBC9@BN9PR11MB5276.namprd11.prod.outlook.com>
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Hi Kevin,

On 3/16/2023 4:52 PM, Tian, Kevin wrote:
>> From: Chatre, Reinette <reinette.chatre@intel.com>
>> Sent: Friday, March 17, 2023 7:38 AM
>>
>>> Based on above, there really can never be an error if we expect the
>>> device to work, so I think there's a misread of the current status.
>>> Dynamic MSI-X support should simply reduce the disruption and chance
>>> of lost interrupts at the device, but the points where we risk that
>>> the host cannot provide the configuration we need are the same.
>>
>> Thank you very much Alex. In this case, please do consider this
>> submission as a submission for inclusion. I'd be happy to resubmit
>> without the "RFC" prefix if that is preferred.
>>
> 
> With that do we still want to keep the error behavior for MSI?
> 
> If no patch5 can be simplified e.g. no need of vfio_irq_ctx_range_allocated()
> and MSI/MSI-X error behaviors become consistent.

Thank you. Yes, if I understand correctly MSI and MSI-X error handling
can become consistent. I'll modify patch 5 to remove
vfio_irq_ctx_range_allocated().

Reinette