linux-kernel - Re: [PATCH v3] xen-pciback: Consider INTx disabled when MSI/MSI-X is enabled

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Message-ID: <Y4S7R2dN7kpJnPpY@mail-itl>
Date:   Mon, 28 Nov 2022 14:44:39 +0100
From:   Marek Marczykowski-Górecki 
        <marmarek@...isiblethingslab.com>
To:     Jason Andryuk <jandryuk@...il.com>
Cc:     linux-kernel@...r.kernel.org, Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
        Jan Beulich <jbeulich@...e.com>,
        "moderated list:XEN HYPERVISOR INTERFACE" 
        <xen-devel@...ts.xenproject.org>
Subject: Re: [PATCH v3] xen-pciback: Consider INTx disabled when MSI/MSI-X is
 enabled

On Mon, Nov 21, 2022 at 05:16:37PM +0100, Marek Marczykowski-Górecki wrote:
> On Mon, Nov 21, 2022 at 10:41:34AM -0500, Jason Andryuk wrote:
> > On Sat, Nov 19, 2022 at 11:33 AM Marek Marczykowski-Górecki
> > <marmarek@...isiblethingslab.com> wrote:
> > >
> > > On Sat, Nov 19, 2022 at 09:36:54AM -0500, Jason Andryuk wrote:
> > > > Hi, Marek,
> > > >
> > > > On Fri, Nov 18, 2022 at 4:46 PM Marek Marczykowski-Górecki
> > > > <marmarek@...isiblethingslab.com> wrote:
> > > > >
> > > > > On Fri, Nov 18, 2022 at 03:46:47PM -0500, Jason Andryuk wrote:
> > > > > > I was trying to test your xen-pciback v3 patch, and I am having
> > > > > > assignment fail consistently now.  It is actually failing to
> > > > > > quarantine to domIO in the first place, which matches the failure from
> > > > > > the other day (when I more carefully read through the logs).  It now
> > > > > > consistently fails to quarantine on every boot unlike the other day
> > > > > > where it happened once.
> > > > >
> > > > > Does this include the very first assignment too, or only after domain
> > > > > reboot? If the latter, maybe some cleanup missed clearing MASKALL?
> > > >
> > > > It's the quarantine during dom0 boot that fails.  Later assignment
> > > > during VM boot fails.  I tried warm reboots and cold boots and it
> > > > happened both times.
> > > >
> > > > I also modified my initrd to halt in there and checked the config
> > > > space.  MASKALL wasn't set at that time.  I need to double check -
> > > > MASKALL may have been unset after dom0 booted in that case.
> > > >
> > > > I'll test more to figure when and how MASKALL is getting set.
> > 
> > I'm testing with a laptop without a battery.  It seems MASKALL remains
> > set when rebooting or when left plugged in.
> > 
> > From unplugged, a cold boot doesn't have MASKALL set and the network vm boots.
> > 
> > After that, rebooting the laptop leaves MASKALL set on the NIC when
> > the laptop reboots.   NIC assignment fails.
> > 
> > Shutdown and later boot while left plugged in keeps MASKALL set.  NIC
> > assignment fails.  I have only tested this scenario for short periods
> > of time, so I don't know if it would eventually clear after a longer
> > time.
> 
> That's interesting, seems like firmware is not resetting the device
> properly. Maybe related to enabled wake on lan?
> 
> Anyway, resetting the device at domain create/destroy is AFAIR normally
> done by pciback (at the instruction by the toolstack). Should it maybe
> be done when assigning to pciback initially too? Or maybe in this
> specific case, device reset doesn't properly clear MASKALL, so pciback
> should clear it explicitly (after ensuring the MSI-X enable is cleared
> too)?

Can you check if `echo 1 > /sys/bus/pci/devices/$SBDF/reset` clears
MASKALL on this device?

I'm tempted to add libxl__device_pci_reset() as part of
libxl__device_pci_assignable_add().

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

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