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From: Jacob Pan <jacob.jun.pan@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Jan Kiszka <jan.kiszka@siemens.com>,
	Ricardo Neri <ricardo.neri@intel.com>,
	Stephane Eranian <eranian@google.com>,
	Ingo Molnar <mingo@kernel.org>,
	Wincy Van <fanwenyi0529@gmail.com>,
	Ashok Raj <ashok.raj@intel.com>, x86 <x86@kernel.org>,
	Andi Kleen <andi.kleen@intel.com>, Borislav Petkov <bp@suse.de>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Juergen Gross <jgross@suse.com>, Tony Luck <tony.luck@intel.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	iommu@lists.linux-foundation.org, jacob.jun.pan@intel.com,
	Philippe Ombredanne <pombredanne@nexb.com>
Subject: Re: [RFC PATCH v4 20/21] iommu/vt-d: hpet: Reserve an interrupt remampping table entry for watchdog
Date: Fri, 21 Jun 2019 10:31:26 -0700
Message-ID: <20190621103126.585ca6d3@jacob-builder> (raw)
In-Reply-To: <alpine.DEB.2.21.1906211732330.5503@nanos.tec.linutronix.de>

On Fri, 21 Jun 2019 17:33:28 +0200 (CEST)
Thomas Gleixner <tglx@linutronix.de> wrote:

> On Wed, 19 Jun 2019, Jacob Pan wrote:
> > On Tue, 18 Jun 2019 01:08:06 +0200 (CEST)
> > Thomas Gleixner <tglx@linutronix.de> wrote:  
> > > 
> > > Unless this problem is not solved and I doubt it can be solved
> > > after talking to IOMMU people and studying manuals,  
> >
> > I agree. modify irte might be done with cmpxchg_double() but the
> > queued invalidation interface for IRTE cache flush is shared with
> > DMA and requires holding a spinlock for enque descriptors, QI tail
> > update etc.
> > 
> > Also, reserving & manipulating IRTE slot for hpet via backdoor
> > might not be needed if the HPET PCI BDF (found in ACPI) can be
> > utilized. But it might need more work to add a fake PCI device for
> > HPET.  
> 
> What would PCI/BDF solve?
I was thinking if HPET is a PCI device then it can naturally
gain slots in IOMMU remapping table IRTEs via PCI MSI code. Then perhaps
it can use the IRQ subsystem to set affinity etc. w/o directly adding
additional helper functions in IRQ remapping code. I have not followed
all the discussions, just a thought.

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Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-24  1:16 [RFC PATCH v4 00/21] Implement an HPET-based hardlockup detector Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 01/21] x86/msi: Add definition for NMI delivery mode Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 02/21] x86/hpet: Expose hpet_writel() in header Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 03/21] x86/hpet: Calculate ticks-per-second in a separate function Ricardo Neri
2019-06-14 15:54   ` Thomas Gleixner
2019-06-14 15:59     ` Thomas Gleixner
2019-06-18 22:48     ` Ricardo Neri
2019-06-18 23:13       ` Thomas Gleixner
2019-05-24  1:16 ` [RFC PATCH v4 04/21] x86/hpet: Add hpet_set_comparator() for periodic and one-shot modes Ricardo Neri
2019-06-14 18:17   ` Thomas Gleixner
2019-06-18 22:48     ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 05/21] x86/hpet: Reserve timer for the HPET hardlockup detector Ricardo Neri
2019-06-11 19:54   ` Thomas Gleixner
2019-06-14  1:14     ` Ricardo Neri
2019-06-14 16:10       ` Thomas Gleixner
2019-06-18 22:48         ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 06/21] x86/hpet: Configure the timer used by the " Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 07/21] watchdog/hardlockup: Define a generic function to detect hardlockups Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 08/21] watchdog/hardlockup: Decouple the hardlockup detector from perf Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 09/21] x86/nmi: Add a NMI_WATCHDOG NMI handler category Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 10/21] watchdog/hardlockup: Add function to enable NMI watchdog on all allowed CPUs at once Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 11/21] x86/watchdog/hardlockup: Add an HPET-based hardlockup detector Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 12/21] watchdog/hardlockup/hpet: Adjust timer expiration on the number of monitored CPUs Ricardo Neri
2019-06-11 20:11   ` Thomas Gleixner
2019-06-18 22:46     ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 13/21] x86/watchdog/hardlockup/hpet: Determine if HPET timer caused NMI Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 14/21] watchdog/hardlockup: Use parse_option_str() to handle "nmi_watchdog" Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 15/21] watchdog/hardlockup/hpet: Only enable the HPET watchdog via a boot parameter Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 16/21] x86/watchdog: Add a shim hardlockup detector Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 17/21] x86/tsc: Switch to perf-based hardlockup detector if TSC become unstable Ricardo Neri
2019-06-07  0:35   ` Stephane Eranian via iommu
2019-06-07 14:14     ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 18/21] x86/apic: Add a parameter for the APIC delivery mode Ricardo Neri
2019-06-16  9:55   ` Thomas Gleixner
2019-06-18 22:47     ` Ricardo Neri
2019-06-18 23:15       ` Thomas Gleixner
2019-05-24  1:16 ` [RFC PATCH v4 19/21] iommu/vt-d: Rework prepare_irte() to support per-irq " Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 20/21] iommu/vt-d: hpet: Reserve an interrupt remampping table entry for watchdog Ricardo Neri
2019-06-16 18:42   ` Thomas Gleixner
2019-06-16 19:21   ` Thomas Gleixner
2019-06-17  8:25     ` Thomas Gleixner
2019-06-17 21:38       ` Stephane Eranian via iommu
2019-06-17 23:08         ` Thomas Gleixner
2019-06-19 15:43           ` Jacob Pan
2019-06-21 15:33             ` Thomas Gleixner
2019-06-21 17:31               ` Jacob Pan [this message]
2019-06-21 18:39                 ` Jacob Pan
2019-06-21 20:05                   ` Thomas Gleixner
2019-06-21 23:55                     ` Ricardo Neri
2019-06-22  7:21                       ` Thomas Gleixner
2019-06-18 22:45       ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 21/21] x86/watchdog/hardlockup/hpet: Support interrupt remapping Ricardo Neri
2019-06-16  8:44   ` Thomas Gleixner
2019-06-16  8:53     ` Thomas Gleixner

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