From: Jim Mattson <[email protected]> commit b119019847fbcac36ed1384f166c91f177d070e7 upstream.
When L0 is executing handle_invept(), the TDP MMU is active. Emulating an L1 INVEPT does require synchronizing the appropriate shadow EPT root(s), but a call to kvm_mmu_sync_roots in this context won't do that. Similarly, the hardware TLB and paging-structure-cache entries associated with the appropriate shadow EPT root(s) must be flushed, but requesting a TLB_FLUSH from this context won't do that either. How did this ever work? KVM always does a sync_roots and TLB flush (in the correct context) when transitioning from L1 to L2. That isn't the best choice for nested VM performance, but it effectively papers over the mistakes here. Remove the unnecessary operations and leave a comment to try to do better in the future. Reported-by: Junaid Shahid <[email protected]> Fixes: bfd0a56b90005f ("nEPT: Nested INVEPT") Cc: Xiao Guangrong <[email protected]> Cc: Nadav Har'El <[email protected]> Cc: Jun Nakajima <[email protected]> Cc: Xinhao Xu <[email protected]> Cc: Yang Zhang <[email protected]> Cc: Gleb Natapov <[email protected]> Cc: Paolo Bonzini <[email protected]> Reviewed-by Peter Shier <[email protected]> Reviewed-by: Junaid Shahid <[email protected]> Signed-off-by: Jim Mattson <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/kvm/vmx/nested.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -4708,13 +4708,11 @@ static int handle_invept(struct kvm_vcpu switch (type) { case VMX_EPT_EXTENT_GLOBAL: + case VMX_EPT_EXTENT_CONTEXT: /* - * TODO: track mappings and invalidate - * single context requests appropriately + * TODO: Sync the necessary shadow EPT roots here, rather than + * at the next emulated VM-entry. */ - case VMX_EPT_EXTENT_CONTEXT: - kvm_mmu_sync_roots(vcpu); - kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu); break; default: BUG_ON(1);
