KVM: nVMX: Switch to vmcs01 to update PML controls on-demand if L2 is active

Browse source

If KVM toggles "CPU dirty logging", a.k.a. Page-Modification Logging (PML),
while L2 is active, temporarily load vmcs01 and immediately update the
relevant controls instead of deferring the update until the next nested
VM-Exit.  For PML, deferring the update is relatively straightforward, but
for several APICv related updates, deferring updates creates ordering and
state consistency problems, e.g. KVM at-large thinks APICv is enabled, but
vmcs01 is still running with stale (and effectively unknown) state.

Convert PML first precisely because it's the simplest case to handle: if
something is broken with the vmcs01 <=> vmcs02 dance, then hopefully bugs
will bisect here.

Reviewed-by: Chao Gao <chao.gao@intel.com>
Link: https://patch.msgid.link/20260109034532.1012993-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

...

This commit is contained in:

Sean Christopherson 2026-01-08 19:45:26 -08:00

parent c3a9a27c79

commit 3e013d0a70

3 changed files with 36 additions and 10 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

5

arch/x86/kvm/vmx/nested.c

View file

40

arch/x86/kvm/vmx/vmx.c

View file

1

arch/x86/kvm/vmx/vmx.h

View file