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From:   isaku.yamahata@intel.com
To:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     isaku.yamahata@intel.com, isaku.yamahata@gmail.com,
        Paolo Bonzini <pbonzini@redhat.com>, erdemaktas@google.com,
        Sean Christopherson <seanjc@google.com>,
        Sagi Shahar <sagis@google.com>,
        David Matlack <dmatlack@google.com>,
        Kai Huang <kai.huang@intel.com>,
        Zhi Wang <zhi.wang.linux@gmail.com>, chen.bo@intel.com,
        hang.yuan@intel.com, tina.zhang@intel.com
Subject: [PATCH v16 054/116] KVM: TDX: Require TDP MMU and mmio caching for TDX
Date:   Mon, 16 Oct 2023 09:14:06 -0700
Message-Id: <e94aec518e1dbb53cd9a6f871edfa7fc0634e172.1697471314.git.isaku.yamahata@intel.com>
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From: Isaku Yamahata <isaku.yamahata@intel.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@intel.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 e1f42fdcd248..91250b2a7081 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 17d119f3c4a8..fda13fd37cae 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