Messages in this thread | | | Subject | Re: [PATCH 2/3] KVM: x86: guest debug: don't inject interrupts while single stepping | From | Jan Kiszka <> | Date | Wed, 17 Mar 2021 10:20:36 +0100 |
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On 16.03.21 18:26, Sean Christopherson wrote: > On Tue, Mar 16, 2021, Jan Kiszka wrote: >> On 16.03.21 17:50, Sean Christopherson wrote: >>> Rather than block all events in KVM, what about having QEMU "pause" the timer? >>> E.g. save MSR_TSC_DEADLINE and APIC_TMICT (or inspect the guest to find out >>> which flavor it's using), clear them to zero, then restore both when >>> single-stepping is disabled. I think that will work? >>> >> >> No one can stop the clock, and timers are only one source of interrupts. >> Plus they do not all come from QEMU, some also from KVM or in-kernel >> sources directly. > > But are any other sources of interrupts a chronic problem? I 100% agree that
If you are debugging a problem, you are not interested in seening problems of the debugger, only real ones of your target. IOW: Yes, they are, even if less likely - for idle VMs.
> this would not be a robust solution, but neither is blocking events in KVM. At > least with this approach, the blast radius is somewhat contained. > >> Would quickly become a mess. > > Maybe, but it'd be Qemu's mess ;-) >
Nope, it would spread to KVM as well, as indicated above.
Jan
-- Siemens AG, T RDA IOT Corporate Competence Center Embedded Linux
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