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From: Michael Kelley <mikelley@microsoft.com>
To: Marc Zyngier <maz@kernel.org>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>,
	"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
	"boqun.feng" <boqun.feng@gmail.com>,
	"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
	"jasowang@redhat.com" <jasowang@redhat.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"marcelo.cerri@canonical.com" <marcelo.cerri@canonical.com>,
	"olaf@aepfle.de" <olaf@aepfle.de>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"apw@canonical.com" <apw@canonical.com>,
	"devel@linuxdriverproject.org" <devel@linuxdriverproject.org>,
	vkuznets <vkuznets@redhat.com>, KY Srinivasan <kys@microsoft.com>,
	"will@kernel.org" <will@kernel.org>,
	Sunil Muthuswamy <sunilmut@microsoft.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: RE: [PATCH v5 2/8] arm64: hyperv: Add hypercall and register access functions
Date: Wed, 6 Nov 2019 17:59:10 +0000	[thread overview]
Message-ID: <DM5PR21MB013730D09CB8BA7658DE57F7D7790@DM5PR21MB0137.namprd21.prod.outlook.com> (raw)
In-Reply-To: <8cdc86e5bcf861c74069e0d349910c94@www.loen.fr>

From: Marc Zyngier <maz@kernel.org>  Sent: Wednesday, November 6, 2019 2:20 AM
> 
> On 2019-10-03 20:12, Michael Kelley wrote:
> > Add ARM64-specific code to make Hyper-V hypercalls and to
> > access virtual processor synthetic registers via hypercalls.
> > Hypercalls use a Hyper-V specific calling sequence with a non-zero
> > immediate value per Section 2.9 of the SMC Calling Convention
> > spec.
> 
> I find this "following the spec by actively sidestepping it" counter
> productive. You (or rather the Hyper-V people) are reinventing the
> wheel (of the slightly square variety) instead of using the standard
> that the whole of the ARM ecosystem seems happy to take advantage
> of.
> 
> I wonder what is the rational for this. If something doesn't quite
> work for Hyper-V, I think we'd all like to know.
> 

I'll go another round internally with the Hyper-V people on this
topic and impress upon them the desire of the Linux community to
have Hyper-V adopt the true spirit of the spec.  But I know they are
fairly set in their approach at this point, regardless of the technical
merits or lack thereof.  Hyper-V is shipping and in use as a commercial
product on ARM64 hardware, which makes it harder to change.  I
hope we can find a way to avoid a complete impasse ....

Michael
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  reply	other threads:[~2019-11-06 17:59 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-03 19:03 [PATCH v5 0/8] Enable Linux guests on Hyper-V on ARM64 Michael Kelley
2019-10-03 19:03 ` [PATCH v5 1/8] arm64: hyperv: Add core Hyper-V include files Michael Kelley
2019-10-03 19:03 ` [PATCH v5 2/8] arm64: hyperv: Add hypercall and register access functions Michael Kelley
2019-11-04  4:36   ` Boqun Feng
2019-11-06  0:40     ` Michael Kelley
2019-11-06 10:19   ` Marc Zyngier
2019-11-06 17:59     ` Michael Kelley [this message]
2019-11-07  9:10       ` Marc Zyngier
2019-11-11 17:16         ` Michael Kelley
2019-10-03 19:03 ` [PATCH v5 3/8] arm64: hyperv: Add memory alloc/free functions for Hyper-V size pages Michael Kelley
2019-11-07 14:19   ` Marc Zyngier
2019-11-08 19:00     ` Michael Kelley
2019-10-03 19:03 ` [PATCH v5 4/8] arm64: hyperv: Add interrupt handlers for VMbus and stimer Michael Kelley
2019-10-03 19:03 ` [PATCH v5 5/8] arm64: hyperv: Add kexec and panic handlers Michael Kelley
2019-10-03 19:03 ` [PATCH v5 6/8] arm64: hyperv: Initialize hypervisor on boot Michael Kelley
2019-10-03 19:03 ` [PATCH v5 7/8] Drivers: hv: vmbus: Add hooks for per-CPU IRQ Michael Kelley
2019-10-03 19:03 ` [PATCH v5 8/8] Drivers: hv: Enable Hyper-V code to be built on ARM64 Michael Kelley

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