On 19/10/2021 08:07, Jan Beulich wrote: > From: Thomas Gleixner <t...@linutronix.de> > > On recent Intel systems the HPET stops working when the system reaches PC10 > idle state. > > The approach of adding PCI ids to the early quirks to disable HPET on > these systems is a whack a mole game which makes no sense. > > Check for PC10 instead and force disable HPET if supported. The check is > overbroad as it does not take ACPI, mwait-idle enablement and command > line parameters into account. That's fine as long as there is at least > PMTIMER available to calibrate the TSC frequency. The decision can be > overruled by adding "clocksource=hpet" on the Xen command line. > > Remove the related PCI quirks for affected Coffee Lake systems as they > are not longer required. That should also cover all other systems, i.e. > Ice Lake, Tiger Lake, and newer generations, which are most likely > affected by this as well. > > Fixes: Yet another hardware trainwreck > Reported-by: Jakub Kicinski <k...@kernel.org> > Signed-off-by: Thomas Gleixner <t...@linutronix.de> > [Linux commit: 6e3cd95234dc1eda488f4f487c281bac8fef4d9b] > > I have to admit that the purpose of checking CPUID5_ECX_INTERRUPT_BREAK > is unclear to me, but I didn't want to diverge in technical aspects from > the Linux commit. > > In mwait_pc10_supported(), besides some cosmetic adjustments, avoid UB > from shifting left a signed 4-bit constant by 28 bits. > > Signed-off-by: Jan Beulich <jbeul...@suse.com>
This breaks booting on recent Intel platforms. Ian: Complete blocker for the release. ~Andrew
