Pin the hrtimer used for VMX-preemption timer emulation
Status from this message: Queued all, thanks.
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Patches in v1 Applied
| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 1/3 | KVM: nVMX: Really make emulated nested preemption timer pinnedarch/ | +1 | 1 reply | |
| 2/3 | KVM: nVMX: Change emulated VMX-preemption timer hrtimer to absolutearch/ | +3 | 0 replies | |
| 3/3 | KVM: nVMX: Migrate the VMX-preemption timerarch/ arch/ arch/ | +15 | 1 reply |
Reviews trailers per patch
All 3 patches have a Reviewed-by or Acked-by.
| Patch | Peter Shier | Oliver Upton |
|---|---|---|
| 1/3 | R-b | R-b |
| 2/3 | R-b | R-b |
| 3/3 | R-b | R-b |
Trailers given in replies are filled; those carried in the patches from earlier versions are outlined with dashes.
Cover letter [PATCH 0/3] Pin the hrtimer used for VMX-preemption timer emulation
I'm still not entirely convinced that the Linux hrtimer can be used to accurately emulate the VMX-preemption timer, but it definitely doesn't work if the hrtimer is on a different logical processor from the vCPU thread that needs to get kicked out of VMX non-root operation.
With these changes, the kvm-unit-test (sent separately) that verifies that a guest can't actually observe a delayed VMX-preemption timer VM-exit passes 99.999% of the time on a 2GHz Skylake system.
It might be possible to improve that pass rate even more by increasing the scaling factor in the virtual IA32_VMX_MISC[4:0], but you'd have to be even more of a stickler than I to go to that extreme.
By the way, what is the point of migrating the hrtimers for the APIC and the PIT, since they aren't even pinned to begin with?
The subject line of the first patch was crafted for you, Sean. :-D
Jim Mattson (3):
KVM: nVMX: Really make emulated nested preemption timer pinned
KVM: nVMX: Change emulated VMX-preemption timer hrtimer to absolute
KVM: nVMX: Migrate the VMX-preemption timer
arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/kvm/irq.c | 2 ++ arch/x86/kvm/vmx/nested.c | 5 +++-- arch/x86/kvm/vmx/vmx.c | 11 +++++++++++ 4 files changed, 18 insertions(+), 2 deletions(-)
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