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

From: Juergen Gross
Date: Fri Sep 03 2021 - 04:49:43 EST


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