linux-kernel - Re: [PATCH v6 12/13] PCI: hv: Add hypercalls to read/write MMIO space

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Message-ID: <ZB3AnngemTf8vKlA@lpieralisi>
Date:   Fri, 24 Mar 2023 16:24:14 +0100
From:   Lorenzo Pieralisi <lpieralisi@...nel.org>
To:     "Michael Kelley (LINUX)" <mikelley@...rosoft.com>
Cc:     "hpa@...or.com" <hpa@...or.com>, KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
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Subject: Re: [PATCH v6 12/13] PCI: hv: Add hypercalls to read/write MMIO space

On Fri, Mar 24, 2023 at 03:13:02PM +0000, Michael Kelley (LINUX) wrote:
> From: Lorenzo Pieralisi <lpieralisi@...nel.org> Sent: Friday, March 24, 2023 7:48 AM
> > 
> > On Wed, Mar 08, 2023 at 06:40:13PM -0800, Michael Kelley wrote:
> > > To support PCI pass-thru devices in Confidential VMs, Hyper-V
> > > has added hypercalls to read and write MMIO space. Add the
> > > appropriate definitions to hyperv-tlfs.h and implement
> > > functions to make the hypercalls.
> > >
> > > Co-developed-by: Dexuan Cui <decui@...rosoft.com>
> > > Signed-off-by: Dexuan Cui <decui@...rosoft.com>
> > > Signed-off-by: Michael Kelley <mikelley@...rosoft.com>
> > > Reviewed-by: Haiyang Zhang <haiyangz@...rosoft.com>
> > > ---
> > >  arch/x86/include/asm/hyperv-tlfs.h  |  3 ++
> > >  drivers/pci/controller/pci-hyperv.c | 64
> > +++++++++++++++++++++++++++++++++++++
> > >  include/asm-generic/hyperv-tlfs.h   | 22 +++++++++++++
> > >  3 files changed, 89 insertions(+)
> > 
> > Nit: I'd squash this in with the patch where the calls are used,
> > don't think this patch is bisectable as it stands (maybe you
> > split them for review purposes, apologies if so).
> > 
> > Lorenzo
> 
> I did split the new code into two patches to make it more
> consumable from a review standpoint.  But I'm not understanding
> what you mean by not being bisectable.  After applying the first
> of the two patches, everything should still compile and work
> even though there are no users of the new hypercalls.  Or maybe
> your concern is that there would be "unused function" warnings?

That's what I meant - that's it.
 
> In any case, squashing the two patches isn't a problem.

Thanks,
Lorenzo