On October 12, 2021 9:02 PM, Gerd Hoffmann wrote: > On Tue, Oct 05, 2021 at 11:39:39AM +0800, Min Xu wrote: > > RFC： https://bugzilla.tianocore.org/show_bug.cgi?id=3429 > > > > TDX guest supports LocalApicTimer. But in current OvmfPkg the > > supported timer is 8254TimerDxe. So > > gUefiOvmfPkgTokenSpaceGuid.PcdTimerSelector > > is introduced to select the running Timer. The Timer driver will check > > the TimerSelector in its entry point. The default Timer is 8254. > > Hmm. > > We already have a local apic timer implementation (XenTimerDxe). Works fine > with kvm, microvm already uses that. See commit 76602f45dcd9 > ("OvmfPkg/Microvm: use XenTimerDxe (lapic timer)"). > > So, first I'd suggest to just use that (maybe rename the thing to avoid > confusion > as it isn't really Xen specific). Thanks for reminder. Let me first do some more investigation about the XenTimerDxe. It will be better to use an existing lapic timer than introducing a new one. > > Next question is whenever there is a need for a runtime switch. I doubt it is > possible to create a virtual machine without lapic, so switching ovmf from > 8254 > (aka pit) to lapic unconditionally should work fine. > Quick smoke test (patch below) shows no obvious problems. Let me do some more investigation. >
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