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From:   "Michael Kelley (LINUX)" <mikelley@microsoft.com>
To:     Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>,
        Saurabh Sengar <ssengar@linux.microsoft.com>
CC:     "tglx@linutronix.de" <tglx@linutronix.de>,
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        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
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        "jgross@suse.com" <jgross@suse.com>,
        "mat.jonczyk@o2.pl" <mat.jonczyk@o2.pl>
Subject: RE: [PATCH v4 5/5] x86/hyperv: VTL support for Hyper-V
Thread-Topic: [PATCH v4 5/5] x86/hyperv: VTL support for Hyper-V
Thread-Index: AQHZZtQDm7r7516jUUWroUo0jRWt9K8eVKeAgAIBzDA=
Date:   Fri, 7 Apr 2023 20:56:29 +0000
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From: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com> Sent: Thursd=
ay, April 6, 2023 7:08 AM
>=20
> On Tue, Apr 04, 2023 at 02:01:04AM -0700, Saurabh Sengar wrote:

[snip]

> > --- /dev/null
> > +++ b/arch/x86/hyperv/hv_vtl.c
> > @@ -0,0 +1,227 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (c) 2023, Microsoft Corporation.
> > + *
> > + * Author:
> > + *   Saurabh Sengar <ssengar@microsoft.com>
> > + */
> > +
> > +#include <asm/apic.h>
> > +#include <asm/boot.h>
> > +#include <asm/desc.h>
> > +#include <asm/i8259.h>
> > +#include <asm/mshyperv.h>
> > +#include <asm/realmode.h>
> > +
> > +extern struct boot_params boot_params;
> > +static struct real_mode_header hv_vtl_real_mode_header;
> > +
> > +void __init hv_vtl_init_platform(void)
> > +{
> > +	pr_info("Linux runs in Hyper-V Virtual Trust Level\n");
> > +
> > +	x86_init.irqs.pre_vector_init =3D x86_init_noop;
> > +	x86_init.timers.timer_init =3D x86_init_noop;
> > +
> > +	x86_platform.get_wallclock =3D get_rtc_noop;
> > +	x86_platform.set_wallclock =3D set_rtc_noop;
>=20
> Nit: this code is VTL feature and hypevisor specific.
> Defining vtl_get_rtc_noop instead of exporting get_rtc_noop would allow t=
o make
> this series less intrusive to the rest of x86 generic code.
>=20
> Reviewed-by: Stanislav Kinsburskii <stanislav.kinsburskii@gmail.com>
>=20

Saurabh's initial version of the code did define its own version of
get/set_rtc_noop().  I had suggested that he use the existing functions
from x86 generic code, and KY had also commented about re-using
existing code wherever possible.  :-)   My suggestion was partly because
the VTL code is already re-using x86_init_noop(), and then just to avoid
code duplication.  Admittedly, there's not much code being duplicated
in these stub functions.  I slightly prefer re-using the existing functions=
,
but don't feel strongly about it.

Michael