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Tue, 30 Mar 2021 01:58:06 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 9NUYfkI7nCIq for ; Tue, 30 Mar 2021 01:58:05 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by smtp2.osuosl.org (Postfix) with ESMTPS id D6352402F8 for ; Tue, 30 Mar 2021 01:58:05 +0000 (UTC) IronPort-SDR: 2K8APLwwIvvyNqZBiROtEO17S0A3J9JYem49T5+qBkGTe+/NeMzknW+sJp4fGqh5XKdTuTtnnP GmnPFdjNBiAA== X-IronPort-AV: E=McAfee;i="6000,8403,9938"; a="276831830" X-IronPort-AV: E=Sophos;i="5.81,289,1610438400"; d="scan'208";a="276831830" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Mar 2021 18:58:03 -0700 IronPort-SDR: 4kBCccE83dlaNL80D5bdqGzxLDPB7kdzuqN0OJRCEslhjw4WhqBUSoiX0wmZgPL78MoAakqoM1 Cwyk1mFWeGBQ== X-IronPort-AV: E=Sophos;i="5.81,289,1610438400"; d="scan'208";a="454801775" Received: from meghadey-mobl1.amr.corp.intel.com (HELO [10.209.158.242]) ([10.209.158.242]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Mar 2021 18:57:54 -0700 Subject: Re: [Patch V2 13/13] genirq/msi: Provide helpers to return Linux IRQ/dev_msi hw IRQ number To: Marc Zyngier References: <1614370277-23235-1-git-send-email-megha.dey@intel.com> <1614370277-23235-14-git-send-email-megha.dey@intel.com> <87y2ebqfw5.wl-maz@kernel.org> <5bed6fea-32e1-d909-0a5c-439d0f0a7dfe@intel.com> <87r1k2f4w2.wl-maz@kernel.org> From: "Dey, Megha" Message-ID: <64602269-5c82-46ce-b2a0-2586e68e258f@intel.com> Date: Tue, 30 Mar 2021 07:27:40 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: <87r1k2f4w2.wl-maz@kernel.org> Content-Language: en-US Cc: alex.williamson@redhat.com, kevin.tian@intel.com, tony.luck@intel.com, dave.jiang@intel.com, ashok.raj@intel.com, kvm@vger.kernel.org, ravi.v.shankar@intel.com, linux-pci@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, jgg@mellanox.com, bhelgaas@google.com, tglx@linutronix.de, dan.j.williams@intel.com, dwmw@amazon.co.uk X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" Hi Marc, On 3/26/2021 6:28 PM, Marc Zyngier wrote: > On Fri, 26 Mar 2021 01:02:43 +0000, > "Dey, Megha" wrote: >> Hi Marc, >> >> On 3/25/2021 10:53 AM, Marc Zyngier wrote: >>> On Fri, 26 Feb 2021 20:11:17 +0000, >>> Megha Dey wrote: >>>> From: Dave Jiang >>>> >>>> Add new helpers to get the Linux IRQ number and device specific index >>>> for given device-relative vector so that the drivers don't need to >>>> allocate their own arrays to keep track of the vectors and hwirq for >>>> the multi vector device MSI case. >>>> >>>> Reviewed-by: Tony Luck >>>> Signed-off-by: Dave Jiang >>>> Signed-off-by: Megha Dey >>>> --- >>>> include/linux/msi.h | 2 ++ >>>> kernel/irq/msi.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ >>>> 2 files changed, 46 insertions(+) >>>> >>>> diff --git a/include/linux/msi.h b/include/linux/msi.h >>>> index 24abec0..d60a6ba 100644 >>>> --- a/include/linux/msi.h >>>> +++ b/include/linux/msi.h >>>> @@ -451,6 +451,8 @@ struct irq_domain *platform_msi_create_irq_domain(struct fwnode_handle *fwnode, >>>> int platform_msi_domain_alloc_irqs(struct device *dev, unsigned int nvec, >>>> irq_write_msi_msg_t write_msi_msg); >>>> void platform_msi_domain_free_irqs(struct device *dev); >>>> +int msi_irq_vector(struct device *dev, unsigned int nr); >>>> +int dev_msi_hwirq(struct device *dev, unsigned int nr); >>>> /* When an MSI domain is used as an intermediate domain */ >>>> int msi_domain_prepare_irqs(struct irq_domain *domain, struct device *dev, >>>> diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c >>>> index 047b59d..f2a8f55 100644 >>>> --- a/kernel/irq/msi.c >>>> +++ b/kernel/irq/msi.c >>>> @@ -581,4 +581,48 @@ struct msi_domain_info *msi_get_domain_info(struct irq_domain *domain) >>>> return (struct msi_domain_info *)domain->host_data; >>>> } >>>> +/** >>>> + * msi_irq_vector - Get the Linux IRQ number of a device vector >>>> + * @dev: device to operate on >>>> + * @nr: device-relative interrupt vector index (0-based). >>>> + * >>>> + * Returns the Linux IRQ number of a device vector. >>>> + */ >>>> +int msi_irq_vector(struct device *dev, unsigned int nr) >>>> +{ >>>> + struct msi_desc *entry; >>>> + int i = 0; >>>> + >>>> + for_each_msi_entry(entry, dev) { >>>> + if (i == nr) >>>> + return entry->irq; >>>> + i++; >>> This obviously doesn't work with Multi-MSI, does it? >> This API is only for devices that support device MSI interrupts. They >> follow MSI-x format and don't support multi MSI (part of MSI). >> >> Not sure if I am missing something here, can you please let me know? > Nothing in the prototype of the function indicates this limitation, > nor does the documentation. And I'm not sure why you should exclude > part of the MSI functionality here. It can't be for performance > reason, so you might as well make sure this works for all the MSI > variants: > > int msi_irq_vector(struct device *dev, unsigned int nr) > { > struct msi_desc *entry; > int irq, index = 0; > > for_each_msi_vector(entry, irq, dev) { > if (index == nr} > return irq; > index++; > } > > return WARN_ON_ONCE(-EINVAL); > } Ok, got it! >>>> + } >>>> + WARN_ON_ONCE(1); >>>> + return -EINVAL; >>>> +} >>>> +EXPORT_SYMBOL_GPL(msi_irq_vector); >>>> + >>>> +/** >>>> + * dev_msi_hwirq - Get the device MSI hw IRQ number of a device vector >>>> + * @dev: device to operate on >>>> + * @nr: device-relative interrupt vector index (0-based). >>>> + * >>>> + * Return the dev_msi hw IRQ number of a device vector. >>>> + */ >>>> +int dev_msi_hwirq(struct device *dev, unsigned int nr) >>>> +{ >>>> + struct msi_desc *entry; >>>> + int i = 0; >>>> + >>>> + for_each_msi_entry(entry, dev) { >>>> + if (i == nr) >>>> + return entry->device_msi.hwirq; >>>> + i++; >>>> + } >>>> + WARN_ON_ONCE(1); >>>> + return -EINVAL; >>>> +} > And this helper would be more generally useful if it returned the n-th > msi_desc entry rather than some obscure field in a substructure. > > struct msi_desc *msi_get_nth_desc(struct device *dev, unsigned int nth) > { > struct msi_desc *entry = NULL; > unsigned int i = 0; > > for_each_msi_entry(entry, dev) { > if (i == nth) > return entry; > > i++; > } > > WARN_ON_ONCE(!entry); > return entry; > } > > You can always wrap it for your particular use case. Yeah, makes sense. > >>>> +EXPORT_SYMBOL_GPL(dev_msi_hwirq); >>>> + >>>> #endif /* CONFIG_GENERIC_MSI_IRQ_DOMAIN */ >>> And what uses these helpers?] >> These helpers are to be used by a driver series(Intel's IDXD driver) >> which is currently stuck due to VFIO refactoring. > Then I's suggest you keep the helpers together with the actual user, > unless this can generally be useful to existing users (exported > symbols without in-tree users is always a bit odd). Yeah in the next submission, we will submit this patch series along with the user driver patch series. > > Thanks, > > M. > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu