fix: only pass TSC deadline feature if the host supports it #4655
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In commit f5906ee we moved the initialization of the list but forgot to change it here. Fixes: f5906ee Signed-off-by: Pablo Barbáchano <[email protected]>
AMD hosts do not have TSC deadline enabled, and that seems to cause issues like in firecracker-microvm#4099. Only expose TSC_DEADLINE to the guest if the host supports it. Closes firecracker-microvm#4099 Signed-off-by: Pablo Barbáchano <[email protected]>
Codecov ReportAll modified and coverable lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## main #4655 +/- ##
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Coverage 82.08% 82.08%
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Files 255 255
Lines 31257 31264 +7
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+ Hits 25656 25663 +7
Misses 5601 5601
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kalyazin
reviewed
Jun 26, 2024
| @@ -247,7 +247,14 @@ impl super::Cpuid { | |||
| // operation using a TSC deadline value. | |||
| // | |||
| // tsc_deadline: 24, | |||
| set_bit(&mut leaf_1.result.ecx, ECX_TSC_DEADLINE_BITINDEX, true); | |||
| let host_leaf_1 = cpuid(0x1); | |||
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Lest we forget: in case this makes it off the draft, we'll need to update the doc: https://github.com/firecracker-microvm/firecracker/blob/main/docs/cpu_templates/cpuid-normalization.md
pb8o
commented
Jun 27, 2024
| set_bit( | ||
| &mut leaf_1.result.ecx, | ||
| ECX_TSC_DEADLINE_BITINDEX, | ||
| host_tsc_deadline, |
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This causes a 40-50% regression in boot time. Currently investigating.
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Superseded by #4666 |
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