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From: Arnd Bergmann <arnd@arndb.de>
To: Michael Kelley <mikelley@microsoft.com>
Cc: Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	"Mark.Rutland@arm.com" <Mark.Rutland@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	gregkh <gregkh@linuxfoundation.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
	linux-efi <linux-efi@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	"wei.liu@kernel.org" <wei.liu@kernel.org>,
	vkuznets <vkuznets@redhat.com>, KY Srinivasan <kys@microsoft.com>,
	Sunil Muthuswamy <sunilmut@microsoft.com>,
	Boqun Feng <boqun.feng@gmail.com>
Subject: Re: [PATCH v7 07/10] arm64: hyperv: Initialize hypervisor on boot
Date: Wed, 26 Aug 2020 09:18:53 +0200
Message-ID: <CAK8P3a3fzXuyamf=sokW59=Ln-ULBBGaSHxKwUeqxT_4sNrQqw@mail.gmail.com> (raw)
In-Reply-To: <MW2PR2101MB1052AD42CC4F9A71F87EFE95D7570@MW2PR2101MB1052.namprd21.prod.outlook.com>

On Tue, Aug 25, 2020 at 11:20 PM Michael Kelley <mikelley@microsoft.com> wrote:
> From: Arnd Bergmann <arnd@arndb.de> Sent: Monday, August 24, 2020 11:34 AM
> > On Mon, Aug 24, 2020 at 6:48 PM Michael Kelley <mikelley@microsoft.com> wrote:
> >
> > I think this has come up before, and I still don't consider it an acceptable
> > hack to hook platform initialization code into the timer code.
> >
> > Please split out the timer into a standalone driver in drivers/clocksource
> > that can get reviewed by the clocksource maintainers.
>
> I see two related topics here.

Agreed

>  First, the Hyper-V clocksource driver is
> drivers/clocksource/hyperv_timer.c.  The code is architecture independent
> and is used today on the x86 side and for ARM64 in this patch series.  A few
> architecture specific calls are satisfied by code under arch/x86, and in this
> patch series, under arch/arm64.  Is there some aspect of this driver that
> needs reconsideration?  I just want to make sure to understand what you
> are getting at.

For the clocksource driver, I would like to see the arm64 specific bits
(the code you add in arch/arm64 that are only relevant to this driver)
moved out of arch/arm64 and into drivers/clocksource, in whatever
form the clocksource maintainers prefer. I would suggest having a
separate file that can get linked along with the architecture-independent
part of that driver.

> Second is the question of where/how to do Hyper-V specific initialization.
> I agree that hanging it off the timer initialization isn't a great approach.
> Should I add a Hyper-V specific initialization call at the appropriate point
> in the ARM64 init sequence?  The x86 side has some structure for handling
> multiple hypervisors, and the Hyper-V initialization code naturally plugs into
> that structure.  I'm certainly open to suggestions on the best way to handle
> it for ARM64.

Yes, that is where I was getting at. Maybe the x86 abstraction for handling
multiple hypervisors can be lifted out of arch/x86/ into common code?

       Arnd

  reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-24 16:46 [PATCH v7 00/10] Enable Linux guests on Hyper-V on ARM64 Michael Kelley
2020-08-24 16:46 ` [PATCH v7 01/10] arm/arm64: smccc-1.1: Add vendor specific owner definition Michael Kelley
2020-08-24 16:46 ` [PATCH v7 02/10] arm64: hyperv: Add core Hyper-V include files Michael Kelley
2020-08-24 18:38   ` Arnd Bergmann
2020-08-24 16:46 ` [PATCH v7 03/10] arm64: hyperv: Add hypercall and register access functions Michael Kelley
2020-08-24 16:46 ` [PATCH v7 04/10] arm64: hyperv: Add memory alloc/free functions for Hyper-V size pages Michael Kelley
2020-08-24 16:46 ` [PATCH v7 05/10] arm64: hyperv: Add interrupt handlers for VMbus and stimer Michael Kelley
2020-08-24 18:54   ` Arnd Bergmann
2020-08-25 22:04     ` Michael Kelley
2020-08-26  7:14       ` Arnd Bergmann
2020-08-24 16:46 ` [PATCH v7 06/10] arm64: hyperv: Add kexec and panic handlers Michael Kelley
2020-08-24 16:46 ` [PATCH v7 07/10] arm64: hyperv: Initialize hypervisor on boot Michael Kelley
2020-08-24 18:33   ` Arnd Bergmann
2020-08-25 21:20     ` Michael Kelley
2020-08-26  7:18       ` Arnd Bergmann [this message]
2020-08-24 16:46 ` [PATCH v7 08/10] Drivers: hv: vmbus: Add hooks for per-CPU IRQ Michael Kelley
2020-08-24 16:46 ` [PATCH v7 09/10] arm64: efi: Export screen_info Michael Kelley
2020-08-24 17:21   ` Ard Biesheuvel
2020-08-24 17:35   ` Greg KH
2020-08-24 17:40     ` Michael Kelley
2020-08-24 17:52       ` Greg KH
2020-08-24 16:46 ` [PATCH v7 10/10] Drivers: hv: Enable Hyper-V code to be built on ARM64 Michael Kelley
2020-08-24 17:24   ` Ard Biesheuvel
2020-08-24 17:28     ` Michael Kelley
2020-08-25  8:47     ` Ben Dooks

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