[PATCH 17/21] KVM: TDX: MTRR: implement get_mt_mask() for TDX

[Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>]

From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>

Although TDX supports only WB for private GPA, it's desirable to support
MTRR for shared GPA.  Always honor guest PAT for shared EPT as what's done
for normal VMs.

Suggested-by: Kai Huang <kai.huang@xxxxxxxxx>
Co-developed-by: Yan Zhao <yan.y.zhao@xxxxxxxxx>
Signed-off-by: Yan Zhao <yan.y.zhao@xxxxxxxxx>
Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
---
TDX MMU part 2 v1:
 - Align with latest vmx code in kvm/queue.
 - Updated patch log.
 - Dropped KVM_BUG_ON() in vt_get_mt_mask(). (Rick)

v19:
 - typo in the commit message
 - Deleted stale paragraph in the commit message
---
 arch/x86/kvm/vmx/main.c    | 10 +++++++++-
 arch/x86/kvm/vmx/tdx.c     |  8 ++++++++
 arch/x86/kvm/vmx/x86_ops.h |  2 ++
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index 5d43b44e2467..8f5dbab9099f 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -168,6 +168,14 @@ static void vt_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa,
 	vmx_load_mmu_pgd(vcpu, root_hpa, pgd_level);
 }
 
+static u8 vt_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
+{
+	if (is_td_vcpu(vcpu))
+		return tdx_get_mt_mask(vcpu, gfn, is_mmio);
+
+	return vmx_get_mt_mask(vcpu, gfn, is_mmio);
+}
+
 static int vt_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
 {
 	if (!is_td(kvm))
@@ -292,7 +300,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
 
 	.set_tss_addr = vmx_set_tss_addr,
 	.set_identity_map_addr = vmx_set_identity_map_addr,
-	.get_mt_mask = vmx_get_mt_mask,
+	.get_mt_mask = vt_get_mt_mask,
 
 	.get_exit_info = vmx_get_exit_info,
 
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 435112562954..50ce24905062 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -374,6 +374,14 @@ int tdx_vm_init(struct kvm *kvm)
 	return 0;
 }
 
+u8 tdx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
+{
+	if (is_mmio)
+		return MTRR_TYPE_UNCACHABLE << VMX_EPT_MT_EPTE_SHIFT;
+
+	return MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT;
+}
+
 int tdx_vcpu_create(struct kvm_vcpu *vcpu)
 {
 	struct kvm_tdx *kvm_tdx = to_kvm_tdx(vcpu->kvm);
diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
index 66829413797d..d8a00ab4651c 100644
--- a/arch/x86/kvm/vmx/x86_ops.h
+++ b/arch/x86/kvm/vmx/x86_ops.h
@@ -128,6 +128,7 @@ int tdx_vm_ioctl(struct kvm *kvm, void __user *argp);
 int tdx_vcpu_create(struct kvm_vcpu *vcpu);
 void tdx_vcpu_free(struct kvm_vcpu *vcpu);
 void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event);
+u8 tdx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio);
 
 int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp);
 
@@ -153,6 +154,7 @@ static inline int tdx_vm_ioctl(struct kvm *kvm, void __user *argp) { return -EOP
 static inline int tdx_vcpu_create(struct kvm_vcpu *vcpu) { return -EOPNOTSUPP; }
 static inline void tdx_vcpu_free(struct kvm_vcpu *vcpu) {}
 static inline void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) {}
+static inline u8 tdx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) { return 0; }
 
 static inline int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp) { return -EOPNOTSUPP; }
 
-- 
2.34.1