linux-kernel - [PATCH 0/2] xen: fix illegal rtc device usage of pv guests

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Message-Id: <20210903084937.19392-1-jgross@suse.com>
Date:   Fri,  3 Sep 2021 10:49:35 +0200
From:   Juergen Gross <jgross@...e.com>
To:     xen-devel@...ts.xenproject.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     Juergen Gross <jgross@...e.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>, stable@...r.kernel.org,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH 0/2] xen: fix illegal rtc device usage of pv guests

A recent change in mc146818_get_time() resulted in WARN splats when
booting a Xen PV guest.

The main reason is that there is a code path resulting in accessing a
RTC device which is not present, which has been made obvious by a
call of WARN() in this case.

This small series is fixing this issue by:

- avoiding the RTC device access from drivers/base/power/trace.c in
  cast there is no legacy RTC device available
- resetting the availability flag of a legacy RTC device for Xen PV
  guests

Juergen Gross (2):
  PM: base: power: don't try to use non-existing RTC for storing data
  xen: reset legacy rtc flag for PV domU

 arch/x86/xen/enlighten_pv.c |  7 +++++++
 drivers/base/power/trace.c  | 10 ++++++++++
 2 files changed, 17 insertions(+)

-- 
2.26.2