[v3,0/5] Add support for capturing the highest observable L2 TSC

Message

Aaron Lewis Nov. 7, 2019, 10:49 p.m. UTC

The L1 hypervisor may include the IA32_TIME_STAMP_COUNTER MSR in the
vmcs12 MSR VM-exit MSR-store area as a way of determining the highest
TSC value that might have been observed by L2 prior to VM-exit. The
current implementation does not capture a very tight bound on this
value.  To tighten the bound, add the IA32_TIME_STAMP_COUNTER MSR to the
vmcs02 VM-exit MSR-store area whenever it appears in the vmcs12 VM-exit
MSR-store area.  When L0 processes the vmcs12 VM-exit MSR-store area
during the emulation of an L2->L1 VM-exit, special-case the
IA32_TIME_STAMP_COUNTER MSR, using the value stored in the vmcs02
VM-exit MSR-store area to derive the value to be stored in the vmcs12
VM-exit MSR-store area.

v2 -> v3:
 - Rename NR_MSR_ENTRIES to NR_LOADSAVE_MSRS
 - Pull setup code for preparing the MSR-store area out of the final commit and
   put it in it's own commit (4/5).
 - Export vmx_find_msr_index() in the final commit instead of in commit 3/5 as
   it isn't until the final commit that we actually use it.

v1 -> v2:
 - Rename function nested_vmx_get_msr_value() to
   nested_vmx_get_vmexit_msr_value().
 - Remove unneeded tag 'Change-Id' from commit messages.

Aaron Lewis (5):
  kvm: nested: Introduce read_and_check_msr_entry()
  kvm: vmx: Rename NR_AUTOLOAD_MSRS to NR_MSR_ENTRIES
  kvm: vmx: Rename function find_msr() to vmx_find_msr_index()
  KVM: nVMX: Prepare MSR-store area
  KVM: nVMX: Add support for capturing highest observable L2 TSC

 arch/x86/kvm/vmx/nested.c | 136 ++++++++++++++++++++++++++++++++------
 arch/x86/kvm/vmx/vmx.c    |  14 ++--
 arch/x86/kvm/vmx/vmx.h    |   9 ++-
 3 files changed, 131 insertions(+), 28 deletions(-)