From: "Jürgen Groß" <jgross@suse.com>
To: Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Joerg Roedel <joro@8bytes.org>,
iommu@lists.linux-foundation.org, linux-hyperv@vger.kernel.org,
Haiyang Zhang <haiyangz@microsoft.com>,
Jon Derrick <jonathan.derrick@intel.com>,
Lu Baolu <baolu.lu@linux.intel.com>, Wei Liu <wei.liu@kernel.org>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Steve Wahl <steve.wahl@hpe.com>,
Dimitri Sivanich <sivanich@hpe.com>, Russ Anderson <rja@hpe.com>,
linux-pci@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
xen-devel@lists.xenproject.org,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Marc Zyngier <maz@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Megha Dey <megha.dey@intel.com>,
Jason Gunthorpe <jgg@mellanox.com>,
Dave Jiang <dave.jiang@intel.com>,
Alex Williamson <alex.williamson@redhat.com>,
Jacob Pan <jacob.jun.pan@intel.com>,
Baolu Lu <baolu.lu@intel.com>, Kevin Tian <kevin.tian@intel.com>,
Dan Williams <dan.j.williams@intel.com>
Subject: Re: [patch RFC 00/38] x86, PCI, XEN, genirq ...: Prepare for device MSI
Date: Sat, 22 Aug 2020 16:19:09 +0200 [thread overview]
Message-ID: <863e2e57-97a4-5625-4aaf-901092e673b1@suse.com> (raw)
In-Reply-To: <20200821002424.119492231@linutronix.de>
On 21.08.20 02:24, Thomas Gleixner wrote:
> First of all, sorry for the horrible long Cc list, which was
> unfortunately unavoidable as this touches the world and some more.
>
> This patch series aims to provide a base to support device MSI (non
> PCI based) in a halfways architecture independent way.
>
> It's a mixed bag of bug fixes, cleanups and general improvements which
> are worthwhile independent of the device MSI stuff. Unfortunately this
> also comes with an evil abuse of the irqdomain system to coerce XEN on
> x86 into compliance without rewriting XEN from scratch.
>
> As discussed in length in this mail thread:
>
> https://lore.kernel.org/r/87h7tcgbs2.fsf@nanos.tec.linutronix.de
>
> the initial attempt of piggypacking device MSI support on platform MSI
> is doomed for various reasons, but creating independent interrupt
> domains for these upcoming magic PCI subdevices which are not PCI, but
> might be exposed as PCI devices is not as trivial as it seems.
>
> The initially suggested and evaluated approach of extending platform
> MSI turned out to be the completely wrong direction and in fact
> platform MSI should be rewritten on top of device MSI or completely
> replaced by it.
>
> One of the main issues is that x86 does not support the concept of irq
> domains associations stored in device::msi_domain and still relies on
> the arch_*_msi_irqs() fallback implementations which has it's own set
> of problems as outlined in
>
> https://lore.kernel.org/r/87bljg7u4f.fsf@nanos.tec.linutronix.de/
>
> in the very same thread.
>
> The main obstacle of storing that pointer is XEN which has it's own
> historical notiion of handling PCI MSI interupts.
>
> This series tries to address these issues in several steps:
>
> 1) Accidental bug fixes
> iommu/amd: Prevent NULL pointer dereference
>
> 2) Janitoring
> x86/init: Remove unused init ops
>
> 3) Simplification of the x86 specific interrupt allocation mechanism
>
> x86/irq: Rename X86_IRQ_ALLOC_TYPE_MSI* to reflect PCI dependency
> x86/irq: Add allocation type for parent domain retrieval
> iommu/vt-d: Consolidate irq domain getter
> iommu/amd: Consolidate irq domain getter
> iommu/irq_remapping: Consolidate irq domain lookup
>
> 4) Consolidation of the X86 specific interrupt allocation mechanism to be as close
> as possible to the generic MSI allocation mechanism which allows to get rid
> of quite a bunch of x86'isms which are pointless
>
> x86/irq: Prepare consolidation of irq_alloc_info
> x86/msi: Consolidate HPET allocation
> x86/ioapic: Consolidate IOAPIC allocation
> x86/irq: Consolidate DMAR irq allocation
> x86/irq: Consolidate UV domain allocation
> PCI: MSI: Rework pci_msi_domain_calc_hwirq()
> x86/msi: Consolidate MSI allocation
> x86/msi: Use generic MSI domain ops
>
> 5) x86 specific cleanups to remove the dependency on arch_*_msi_irqs()
>
> x86/irq: Move apic_post_init() invocation to one place
> z86/pci: Reducde #ifdeffery in PCI init code
> x86/irq: Initialize PCI/MSI domain at PCI init time
> irqdomain/msi: Provide DOMAIN_BUS_VMD_MSI
> PCI: vmd: Mark VMD irqdomain with DOMAIN_BUS_VMD_MSI
> PCI: MSI: Provide pci_dev_has_special_msi_domain() helper
> x86/xen: Make xen_msi_init() static and rename it to xen_hvm_msi_init()
> x86/xen: Rework MSI teardown
> x86/xen: Consolidate XEN-MSI init
> irqdomain/msi: Allow to override msi_domain_alloc/free_irqs()
> x86/xen: Wrap XEN MSI management into irqdomain
> iommm/vt-d: Store irq domain in struct device
> iommm/amd: Store irq domain in struct device
> x86/pci: Set default irq domain in pcibios_add_device()
> PCI/MSI: Allow to disable arch fallbacks
> x86/irq: Cleanup the arch_*_msi_irqs() leftovers
> x86/irq: Make most MSI ops XEN private
>
> This one is paving the way to device MSI support, but it comes
> with an ugly and evil hack. The ability of overriding the default
> allocation/free functions of an MSI irq domain is useful in general as
> (hopefully) demonstrated with the device MSI POC, but the abuse
> in context of XEN is evil. OTOH without enough XENology and without
> rewriting XEN from scratch wrapping XEN MSI handling into a pseudo
> irq domain is a reasonable step forward for mere mortals with severly
> limited XENology. One day the XEN folks might make it a real irq domain.
> Perhaps when they have to support the same mess on other architectures.
> Hope dies last...
>
> At least the mechanism to override alloc/free turned out to be useful
> for implementing the base infrastructure for device MSI. So it's not a
> completely lost case.
>
> 6) X86 specific preparation for device MSI
>
> x86/irq: Add DEV_MSI allocation type
> x86/msi: Let pci_msi_prepare() handle non-PCI MSI
>
> 7) Generic device MSI infrastructure
>
> platform-msi: Provide default irq_chip:ack
> platform-msi: Add device MSI infrastructure
>
> 8) Infrastructure for and a POC of an IMS (Interrupt Message
> Storm) irq domain and irqchip implementation
>
> irqdomain/msi: Provide msi_alloc/free_store() callbacks
> irqchip: Add IMS array driver - NOT FOR MERGING
>
> The whole lot is also available from git:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git device-msi
>
> This has been tested on Intel/AMD/KVM but lacks testing on:
>
> - HYPERV (-ENODEV)
> - VMD enabled systems (-ENODEV)
> - XEN (-ENOCLUE)
Tested to work in Xen dom0. Network is running fine with eth0 MSI
interrupts being routed through Xen.
You can add my:
Tested-by: Juergen Gross <jgross@suse.com>
Juergen
prev parent reply other threads:[~2020-08-22 14:19 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-21 0:24 [patch RFC 00/38] x86, PCI, XEN, genirq ...: Prepare for device MSI Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 01/38] iommu/amd: Prevent NULL pointer dereference Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 02/38] x86/init: Remove unused init ops Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 03/38] x86/irq: Rename X86_IRQ_ALLOC_TYPE_MSI* to reflect PCI dependency Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 04/38] x86/irq: Add allocation type for parent domain retrieval Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 05/38] iommu/vt-d: Consolidate irq domain getter Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 06/38] iommu/amd: " Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 07/38] iommu/irq_remapping: Consolidate irq domain lookup Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 08/38] x86/irq: Prepare consolidation of irq_alloc_info Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 09/38] x86/msi: Consolidate HPET allocation Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 10/38] x86/ioapic: Consolidate IOAPIC allocation Thomas Gleixner
2020-08-26 8:40 ` Boqun Feng
2020-08-26 9:53 ` Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 11/38] x86/irq: Consolidate DMAR irq allocation Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 12/38] x86/irq: Consolidate UV domain allocation Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 13/38] PCI: MSI: Rework pci_msi_domain_calc_hwirq() Thomas Gleixner
2020-08-25 20:03 ` Bjorn Helgaas
2020-08-25 21:11 ` Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 14/38] x86/msi: Consolidate MSI allocation Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 15/38] x86/msi: Use generic MSI domain ops Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 16/38] x86/irq: Move apic_post_init() invocation to one place Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 17/38] x86/pci: Reducde #ifdeffery in PCI init code Thomas Gleixner
2020-08-25 20:20 ` Bjorn Helgaas
2020-08-21 0:24 ` [patch RFC 18/38] x86/irq: Initialize PCI/MSI domain at PCI init time Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 19/38] irqdomain/msi: Provide DOMAIN_BUS_VMD_MSI Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 20/38] PCI: vmd: Mark VMD irqdomain with DOMAIN_BUS_VMD_MSI Thomas Gleixner
2020-08-25 20:04 ` Bjorn Helgaas
2020-08-21 0:24 ` [patch RFC 21/38] PCI: MSI: Provide pci_dev_has_special_msi_domain() helper Thomas Gleixner
2020-08-25 20:16 ` Bjorn Helgaas
2020-08-21 0:24 ` [patch RFC 22/38] x86/xen: Make xen_msi_init() static and rename it to xen_hvm_msi_init() Thomas Gleixner
2020-08-24 4:48 ` Jürgen Groß
2020-08-21 0:24 ` [patch RFC 23/38] x86/xen: Rework MSI teardown Thomas Gleixner
2020-08-24 5:09 ` Jürgen Groß
2020-08-21 0:24 ` [patch RFC 24/38] x86/xen: Consolidate XEN-MSI init Thomas Gleixner
2020-08-24 4:59 ` Jürgen Groß
2020-08-24 21:21 ` Thomas Gleixner
2020-08-25 4:21 ` Jürgen Groß
2020-08-25 9:51 ` Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 25/38] irqdomain/msi: Allow to override msi_domain_alloc/free_irqs() Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 26/38] x86/xen: Wrap XEN MSI management into irqdomain Thomas Gleixner
2020-08-24 6:21 ` Jürgen Groß
2020-08-25 7:57 ` Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 27/38] iommm/vt-d: Store irq domain in struct device Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 28/38] iommm/amd: " Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 29/38] x86/pci: Set default irq domain in pcibios_add_device() Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 30/38] PCI/MSI: Allow to disable arch fallbacks Thomas Gleixner
2020-08-25 20:07 ` Bjorn Helgaas
2020-08-25 21:28 ` Thomas Gleixner
2020-08-25 21:35 ` Bjorn Helgaas
2020-08-25 21:40 ` Thomas Gleixner
2020-08-25 22:03 ` Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 31/38] x86/irq: Cleanup the arch_*_msi_irqs() leftovers Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 32/38] x86/irq: Make most MSI ops XEN private Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 33/38] x86/irq: Add DEV_MSI allocation type Thomas Gleixner
2020-08-21 0:24 ` [patch RFC 34/38] x86/msi: Let pci_msi_prepare() handle non-PCI MSI Thomas Gleixner
2020-08-25 20:24 ` Bjorn Helgaas
2020-08-25 21:30 ` Thomas Gleixner
2020-08-25 21:50 ` Bjorn Helgaas
2020-08-21 0:24 ` [patch RFC 35/38] platform-msi: Provide default irq_chip::ack Thomas Gleixner
2020-08-21 0:25 ` [patch RFC 36/38] platform-msi: Add device MSI infrastructure Thomas Gleixner
2020-08-21 0:25 ` [patch RFC 37/38] irqdomain/msi: Provide msi_alloc/free_store() callbacks Thomas Gleixner
2020-08-21 0:25 ` [patch RFC 38/38] irqchip: Add IMS array driver - NOT FOR MERGING Thomas Gleixner
2020-08-21 12:45 ` Jason Gunthorpe
2020-08-21 19:47 ` Thomas Gleixner
2020-08-21 20:17 ` Jason Gunthorpe
2020-08-21 23:47 ` Thomas Gleixner
2020-08-22 0:51 ` Jason Gunthorpe
2020-08-22 1:34 ` Thomas Gleixner
2020-08-22 23:05 ` Jason Gunthorpe
2020-08-23 8:03 ` Thomas Gleixner
2020-08-22 14:19 ` Jürgen Groß [this message]
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