Re: [PATCH 0/2] Re-factoring passthrough/pci.c and adding place-holder code for ARM/PCI

From: "Jan Beulich" <JBeulich@suse.com>
To: Manish Jaggi <mjaggi@caviumnetworks.com>
Cc: "Prasun.kapoor@cavium.com" <Prasun.kapoor@cavium.com>,
	Ian Campbell <Ian.Campbell@citrix.com>,
	Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
	Vijaya Kumar <Vijaya.Kumar@caviumnetworks.com>,
	Julien Grall <julien.grall@linaro.org>,
	xen Devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH 0/2] Re-factoring passthrough/pci.c and adding place-holder code for ARM/PCI
Date: Tue, 14 Apr 2015 10:07:56 +0100	[thread overview]
Message-ID: <552CF50C0200007800071C47@mail.emea.novell.com> (raw)
In-Reply-To: <552B724A.8080400@caviumnetworks.com>

>>> On 13.04.15 at 09:37, <mjaggi@caviumnetworks.com> wrote:
> Xen currently does not have PCI support for ARM builds. This patch set
> makes the code compilable for ARM PCI and adds places-holder code
> which would be replaced with PCI pass-through support patch series.
> 
> Re-factor MSI Handling
> -------------
> There is a some x86 specific code which is found in common code:
> xen/drivers/passthrough/pci.c which needs to be re factored.
> 
> MSI/X are configured and handled by dom0 or domU code on ARM64 and is not
> required to be part of common code. However there are functions which are
> used as part of common code and calls to these functions cannot be easily
> re factored like pci_cleanup_msi.

I can only second Julien's reply here: Without explanation (here,
not by reference to some past discussion) how you envision MSI
to work securely when you leave control of it to DomU-s there's
very little point in separating out MSI from PCI code.

Also please make sure you Cc all involved maintainers especially
on non- trivial and potentially controversial patches like these.

Jan