[v2,03/24] KVM: x86/mmu: Do not enable page track for TD guest

Commit Message

Yan Zhao Nov. 12, 2024, 7:35 a.m. UTC

Fail kvm_page_track_write_tracking_enabled() if VM type is TDX to make the
external page track user fail in kvm_page_track_register_notifier() since
TDX does not support write protection and hence page track.

No need to fail KVM internal users of page track (i.e. for shadow page),
because TDX is always with EPT enabled and currently TDX module does not
emulate and send VMLAUNCH/VMRESUME VMExits to VMM.

Suggested-by: Paolo Bonzini <[e-mail]>
Signed-off-by: Yan Zhao <[e-mail]>
Reviewed-by: Binbin Wu <[e-mail]>
Cc: Yuan Yao <[e-mail]>
---
TDX MMU part 2 v2:
- Move the checking of VM type from kvm_page_track_write_tracking_enabled()
  to kvm_enable_external_write_tracking() to make
  kvm_page_track_register_notifier() fail. (Paolo)
- Updated patch msg (Yan)
- Added Paolo's Suggested-by tag since the patch is simple enough and the
  current implementation was suggested by Paolo (Yan)

v19:
- drop TDX: from the short log
- Added reviewed-by: BinBin
---
 arch/x86/kvm/mmu/page_track.c | 3 +++
 1 file changed, 3 insertions(+)

Patch

diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c
index 561c331fd6ec..1b17b12393a8 100644
--- a/arch/x86/kvm/mmu/page_track.c
+++ b/arch/x86/kvm/mmu/page_track.c
@@ -172,6 +172,9 @@  static int kvm_enable_external_write_tracking(struct kvm *kvm)
 	struct kvm_memory_slot *slot;
 	int r = 0, i, bkt;
 
+	if (kvm->arch.vm_type == KVM_X86_TDX_VM)
+		return -EOPNOTSUPP;
+
 	mutex_lock(&kvm->slots_arch_lock);
 
 	/*