From: Hans de Goede <hdegoede@redhat.com>
To: Luis Chamberlain <mcgrof@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Darren Hart <dvhart@infradead.org>,
Andy Shevchenko <andy@infradead.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J . Wysocki" <rafael@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H . Peter Anvin" <hpa@zytor.com>,
Jonathan Corbet <corbet@lwn.net>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Peter Jones <pjones@redhat.com>, Dave Olsthoorn <dave@bewaar.me>,
x86@kernel.org, platform-driver-x86@vger.kernel.org,
linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, linux-input@vger.kernel.org
Subject: Re: [PATCH v7 2/8] efi: Add embedded peripheral firmware support
Date: Fri, 15 Nov 2019 13:09:59 +0100 [thread overview]
Message-ID: <d7546f63-5472-b867-4e79-912edf9cfa6c@redhat.com> (raw)
In-Reply-To: <20191114215009.GF11244@42.do-not-panic.com>
Hi,
On 14-11-2019 22:50, Luis Chamberlain wrote:
> On Thu, Nov 14, 2019 at 09:48:38PM +0100, Hans de Goede wrote:
<snip>
>> But I guess what you really want is some error to be thrown if someone
>> calls firmware_request_platform() before we are ready.
>
> Yes.
>
>> I guess I could make efi_check_for_embedded_firmwares() which scans
>> for known firmwares and saved a copy set a flag that it has run.
>>
>> And then combine that with making efi_get_embedded_fw() (which underpins
>> firmware_request_platform()) print a warning when called if that flag
>> is not set yet.
<snip>
> That'd be great.
So I've been working on this, my first though was to use WARN_ON as
calling this too early would be a bug, but there is a bunch of
normal circumstances where efi_check_for_embedded_firmwares() never
runs. One of the being classic BIOS boot, but e.g. also when running
paravirtualized in a paravirt env. using UEFI.
Normally we should not end up calling efi_get_embedded_fw() in those
cases, for one it is unlikely for any drivers using firmware_request_platform()
to be used in such an environment, and if we somehow do end up with
a case where firmware_request_platform() is called, since the EFI
emebedded fw fallback then will not work I would expect a copy of
the necessary fw to be under /lib/firmware so we never hit the fallback.
This all makes efi_get_embedded_fw() getting called in cases where
efi_check_for_embedded_firmwares() will never run unlikely, but not
impossible. Making a WARN_ON the wrong thing to do so for v8 of this
patch-set I will add a pr_warn for this.
Note I've looked into detecting all the circumstances where it is normal
for efi_check_for_embedded_firmwares() to never run, but after tracing
the call path leading up to it getting called I've found that a check
for that is complicated and more importantly error-prone and likely
to get out of sync with reality if any of the functions higher up
the call path ever change the conditions.
So a pr_warn it is, and since as explained one would normally not
expect to ever hit the fallback on systems where
efi_check_for_embedded_firmwares() does not get called, I see no
harm in simply always printing the warning if
efi_check_for_embedded_firmwares() was not called.
Regards,
Hans
next prev parent reply other threads:[~2019-11-15 12:10 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-04 14:50 [PATCH v7 0/8] efi/firmware/platform-x86: Add EFI embedded fw support Hans de Goede
2019-10-04 14:50 ` [PATCH v7 1/8] efi: Export boot-services code and data as debugfs-blobs Hans de Goede
2019-10-09 13:07 ` Ard Biesheuvel
2019-10-09 13:18 ` Hans de Goede
2019-10-09 13:35 ` Ard Biesheuvel
2019-10-09 13:59 ` Hans de Goede
2019-10-09 14:01 ` Ard Biesheuvel
2019-10-14 9:11 ` Luis Chamberlain
2019-11-14 11:31 ` Hans de Goede
2019-10-04 14:50 ` [PATCH v7 2/8] efi: Add embedded peripheral firmware support Hans de Goede
2019-10-11 14:48 ` Luis Chamberlain
2019-11-14 11:27 ` Hans de Goede
2019-11-14 19:42 ` Luis Chamberlain
2019-11-14 20:13 ` Hans de Goede
2019-11-14 20:48 ` Hans de Goede
2019-11-14 21:50 ` Luis Chamberlain
2019-11-15 12:09 ` Hans de Goede [this message]
2019-10-04 14:50 ` [PATCH v7 3/8] firmware: Rename FW_OPT_NOFALLBACK to FW_OPT_NOFALLBACK_SYSFS Hans de Goede
2019-10-11 15:02 ` Luis Chamberlain
2019-11-14 20:22 ` Hans de Goede
2019-10-04 14:50 ` [PATCH v7 4/8] firmware: Add new platform fallback mechanism and firmware_request_platform() Hans de Goede
2019-10-04 19:33 ` kbuild test robot
2019-10-04 20:45 ` kbuild test robot
2019-10-04 23:17 ` Dmitry Torokhov
2019-10-05 9:53 ` Hans de Goede
2019-10-11 15:31 ` Luis Chamberlain
2019-10-11 15:29 ` Luis Chamberlain
2019-11-14 11:32 ` Hans de Goede
2019-10-04 14:50 ` [PATCH v7 5/8] Input: silead - Switch to firmware_request_platform for retreiving the fw Hans de Goede
2019-10-11 0:47 ` Dmitry Torokhov
2019-10-04 14:50 ` [PATCH v7 6/8] Input: icn8505 " Hans de Goede
2019-10-11 0:47 ` Dmitry Torokhov
2019-10-04 14:50 ` [PATCH v7 7/8] platform/x86: touchscreen_dmi: Add EFI embedded firmware info support Hans de Goede
2019-10-05 3:03 ` kbuild test robot
2019-10-05 7:13 ` kbuild test robot
2019-10-04 14:50 ` [PATCH v7 8/8] platform/x86: touchscreen_dmi: Add info for the Chuwi Vi8 Plus tablet Hans de Goede
2019-10-07 14:19 ` [PATCH v7 0/8] efi/firmware/platform-x86: Add EFI embedded fw support Ingo Molnar
2019-10-08 9:35 ` Hans de Goede
2019-10-08 11:05 ` Ingo Molnar
2019-10-11 14:10 ` Luis Chamberlain
2019-10-11 14:31 ` Hans de Goede
2019-10-11 15:38 ` Luis Chamberlain
2019-10-11 16:38 ` Greg Kroah-Hartman
2019-10-14 9:22 ` Luis Chamberlain
2019-10-14 9:29 ` Greg Kroah-Hartman
2019-10-14 10:31 ` Luis Chamberlain
2019-10-14 10:57 ` Greg Kroah-Hartman
2019-10-16 12:45 ` Luis Chamberlain
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