linux-kernel - [PATCH v18 059/121] KVM: TDX: Require TDP MMU and mmio caching for TDX

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Date: Mon, 22 Jan 2024 15:53:35 -0800
From: isaku.yamahata@...el.com
To: kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: isaku.yamahata@...el.com,
	isaku.yamahata@...il.com,
	Paolo Bonzini <pbonzini@...hat.com>,
	erdemaktas@...gle.com,
	Sean Christopherson <seanjc@...gle.com>,
	Sagi Shahar <sagis@...gle.com>,
	Kai Huang <kai.huang@...el.com>,
	chen.bo@...el.com,
	hang.yuan@...el.com,
	tina.zhang@...el.com
Subject: [PATCH v18 059/121] KVM: TDX: Require TDP MMU and mmio caching for TDX

From: Isaku Yamahata <isaku.yamahata@...el.com>

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@...el.com>
---
 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 f338b85d6d5b..7db152f46d82 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -104,6 +104,7 @@ 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 f55ac09edc60..e77c045dca84 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -62,6 +62,17 @@ 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