Re: [PATCH] x86/PCI: Revert: "Clip only host bridge windows for E820 regions"

From: Bjorn Helgaas <helgaas@kernel.org>
To: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: "Hans de Goede" <hdegoede@redhat.com>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	"Mika Westerberg" <mika.westerberg@linux.intel.com>,
	"Krzysztof Wilczyński" <kw@linux.com>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Myron Stowe" <myron.stowe@redhat.com>,
	"Juha-Pekka Heikkila" <juhapekka.heikkila@gmail.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"H . Peter Anvin" <hpa@zytor.com>,
	"Benoit Grégoire" <benoitg@coeus.ca>,
	"Hui Wang" <hui.wang@canonical.com>,
	linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	"Keith Busch" <kbusch@kernel.org>, "Jens Axboe" <axboe@fb.com>,
	"Christoph Hellwig" <hch@lst.de>,
	"Sagi Grimberg" <sagi@grimberg.me>,
	linux-nvme@lists.infradead.org
Subject: Re: [PATCH] x86/PCI: Revert: "Clip only host bridge windows for E820 regions"
Date: Tue, 14 Jun 2022 18:01:28 -0500	[thread overview]
Message-ID: <20220614230128.GA901712@bhelgaas> (raw)
In-Reply-To: <6eae37ce-dd44-9c32-3f68-2b4e102dce8e@igalia.com>

[+cc NVMe folks]

On Tue, Jun 14, 2022 at 07:49:27PM -0300, Guilherme G. Piccoli wrote:
> On 14/06/2022 12:47, Hans de Goede wrote:
> > [...]
> > 
> > Have you looked at the log of the failed boot in the Steam Deck kernel
> > bugzilla? Everything there seems to work just fine and then the system
> > just hangs. I think that maybe it cannot find its root disk, so maybe
> > an NVME issue ?
> 
> *Exactly* that - NVMe device is the root disk, it cannot boot since the
> device doesn't work, hence no rootfs =)

Beginning of thread: https://lore.kernel.org/r/20220612144325.85366-1-hdegoede@redhat.com

Steam Deck broke because we erroneously trimmed out the PCI host
bridge window where BIOS had placed most devices, successfully
reassigned all the PCI bridge windows and BARs, but some devices,
apparently including NVMe, didn't work at the new addresses.

Do you NVMe folks know of gotchas in this area?  I want to know
because we'd like to be able to move devices around someday to make
room for hot-added devices.

This reassignment happened before drivers claimed the devices, so from
a PCI point of view, I don't know why the NVMe device wouldn't work at
the new address.

Bjorn