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References: <20210906094927.524106-1-schnelle@linux.ibm.com>
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From: Linas Vepstas <linasvepstas@gmail.com>
Date: Mon, 6 Sep 2021 21:05:14 -0500
Message-ID: <CAHrUA34TK6U4TB34FHejott9TdFvSgAedOpmro-Uj2ZwnvzecQ@mail.gmail.com>
Subject: Re: [PATCH 0/5] s390/pci: automatic error recovery
To: Niklas Schnelle <schnelle@linux.ibm.com>
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On Mon, Sep 6, 2021 at 4:49 AM Niklas Schnelle <schnelle@linux.ibm.com>
wrote:

>  I believe we might be the first
> implementation of PCI device recovery in a virtualized setting requiring
> us to
> coordinate the device reset with the hypervisor platform by issuing a
> disable
> and re-enable to the platform as well as starting the recovery following
> a platform event.
>

I recall none of the details, but SRIOV is a standardized system for
sharing a PCI device across multiple virtual machines. It has detailed info
on what the hypervisor must do, and what the local OS instance must do to
accomplish this.  It's part of the PCI standard, and its more than a decade
old now, maybe two. Being a part of the PCI standard, it was interoperable
with error recovery, to the best of my recollection. At the time it was
introduced, it got pushed very aggressively.  The x86 hypervisor vendors
were aiming at the heart of zseries, and were militant about it.

-- Linas

-- 
Patrick: Are they laughing at us?
Sponge Bob: No, Patrick, they are laughing next to us.

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Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div dir=3D"ltr"><br></div><br><div class=3D"gmail_quote">=
<div dir=3D"ltr" class=3D"gmail_attr">On Mon, Sep 6, 2021 at 4:49 AM Niklas=
 Schnelle &lt;<a href=3D"mailto:schnelle@linux.ibm.com">schnelle@linux.ibm.=
com</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"marg=
in:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1e=
x">=C2=A0I believe we might be the first<br>
implementation of PCI device recovery in a virtualized setting requiring us=
 to<br>
coordinate the device reset with the hypervisor platform by issuing a disab=
le<br>
and re-enable to the platform as well as starting the recovery following<br=
>
a platform event.<br></blockquote><div><br></div><div>I recall none of the =
details, but SRIOV is a standardized system for sharing a PCI device across=
 multiple virtual machines. It has detailed info on what the hypervisor mus=
t do, and what the local OS instance must do to accomplish this.=C2=A0 It&#=
39;s part of the PCI standard, and its more than a decade old now, maybe tw=
o. Being a part of the PCI standard, it was interoperable with error recove=
ry, to the best of my recollection. At the time it was introduced, it got p=
ushed very aggressively.=C2=A0 The x86 hypervisor vendors were aiming at th=
e heart of zseries, and were militant about it. <br></div></div><div class=
=3D"gmail_quote"><br></div><div class=3D"gmail_quote">-- Linas<br clear=3D"=
all"></div><br>-- <br><div dir=3D"ltr" class=3D"gmail_signature"><div dir=
=3D"ltr"><div>Patrick: Are they laughing at us?</div><div>Sponge Bob: No, P=
atrick, they are laughing next to us.</div><div>=C2=A0<br></div><br></div><=
/div></div>

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