On Thu, 2021-12-16 at 10:27 -0600, Tom Lendacky wrote: > On 12/15/21 8:56 AM, David Woodhouse wrote: > > Doing the INIT/SIPI/SIPI in parallel for all APs and *then* waiting for > > them shaves about 80% off the AP bringup time on a 96-thread socket > > Skylake box (EC2 c5.metal) — from about 500ms to 100ms. > > > > There are more wins to be had with further parallelisation, but this is > > the simple part. > > I applied this series and began booting a regular non-SEV guest and hit a > failure at 39 vCPUs. No panic or warning, just a reset and OVMF was > executing again. I'll try to debug what's going, but not sure how quickly > I'll arrive at anything. Thanks for testing. This is working for me with BIOS and EFI boots in qemu and real hardware but it's mostly been Intel so far. I'll try harder on an AMD box. Anything else special about your setup, kernel config or qemu invocation that might help me reproduce? If it can repro without KVM, 'qemu -d in_asm' can be extremely useful for this kind of thing btw.
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