[PATCH v15 054/115] KVM: TDX: Require TDP MMU and mmio caching for TDX

[isaku . yamahata]

From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>

As TDP MMU is becoming main stream than the legacy MMU, the legacy MMU
support for TDX isn't implemented.  TDX requires KVM mmio caching.  Disable
TDX support when TDP MMU or mmio caching aren't supported.

Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
 arch/x86/kvm/mmu/mmu.c  |  1 +
 arch/x86/kvm/vmx/main.c | 11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 5b48ac4a5fbc..4e9343e759f6 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -103,6 +103,7 @@ module_param_named(flush_on_reuse, force_flush_and_sync_on_reuse, bool, 0644);
  * If the hardware supports that we don't need to do shadow paging.
  */
 bool tdp_enabled = false;
+EXPORT_SYMBOL_GPL(tdp_enabled);
 
 static bool __ro_after_init tdp_mmu_allowed;
 
diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index c4cf88987b00..debb48f19cfa 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -58,6 +58,17 @@ static __init int vt_hardware_setup(void)
 	if (enable_ept)
 		kvm_mmu_set_ept_masks(enable_ept_ad_bits,
 				      cpu_has_vmx_ept_execute_only());
+	/* TDX requires KVM TDP MMU. */
+	if (enable_tdx && !tdp_enabled) {
+		enable_tdx = false;
+		pr_warn_ratelimited("TDX requires TDP MMU.  Please enable TDP MMU for TDX.\n");
+	}
+
+	/* TDX requires MMIO caching. */
+	if (enable_tdx && !enable_mmio_caching) {
+		enable_tdx = false;
+		pr_warn_ratelimited("TDX requires mmio caching.  Please enable mmio caching for TDX.\n");
+	}
 
 	enable_tdx = enable_tdx && !tdx_hardware_setup(&vt_x86_ops);
 
-- 
2.25.1