linux-kernel - [PATCH 29/30] KVM: x86/mmu: Taking guest pa into consideration when calculate tdp level

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Message-ID: <20250220170604.2279312-30-pbonzini@redhat.com>
Date: Thu, 20 Feb 2025 12:06:03 -0500
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org
Cc: seanjc@...gle.com,
	Yan Zhao <yan.y.zhao@...el.com>,
	Rick Edgecombe <rick.p.edgecombe@...el.com>,
	Xiaoyao Li <xiaoyao.li@...el.com>
Subject: [PATCH 29/30] KVM: x86/mmu: Taking guest pa into consideration when calculate tdp level

From: Xiaoyao Li <xiaoyao.li@...el.com>

For TDX, the maxpa (CPUID.0x80000008.EAX[7:0]) is fixed as native and
the max_gpa (CPUID.0x80000008.EAX[23:16]) is configurable and used
to configure the EPT level and GPAW.

Use max_gpa to determine the TDP level.

Signed-off-by: Xiaoyao Li <xiaoyao.li@...el.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/cpuid.c   | 14 ++++++++++++++
 arch/x86/kvm/cpuid.h   |  1 +
 arch/x86/kvm/mmu/mmu.c |  9 ++++++++-
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 936c5dd13bd5..7ff84079c1f4 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -494,6 +494,20 @@ int cpuid_query_maxphyaddr(struct kvm_vcpu *vcpu)
 	return 36;
 }
 
+int cpuid_query_maxguestphyaddr(struct kvm_vcpu *vcpu)
+{
+	struct kvm_cpuid_entry2 *best;
+
+	best = kvm_find_cpuid_entry(vcpu, 0x80000000);
+	if (!best || best->eax < 0x80000008)
+		goto not_found;
+	best = kvm_find_cpuid_entry(vcpu, 0x80000008);
+	if (best)
+		return (best->eax >> 16) & 0xff;
+not_found:
+	return 0;
+}
+
 /*
  * This "raw" version returns the reserved GPA bits without any adjustments for
  * encryption technologies that usurp bits.  The raw mask should be used if and
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 91bde94519f9..46e059b47825 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -37,6 +37,7 @@ void __init kvm_init_xstate_sizes(void);
 u32 xstate_required_size(u64 xstate_bv, bool compacted);
 
 int cpuid_query_maxphyaddr(struct kvm_vcpu *vcpu);
+int cpuid_query_maxguestphyaddr(struct kvm_vcpu *vcpu);
 u64 kvm_vcpu_reserved_gpa_bits_raw(struct kvm_vcpu *vcpu);
 
 static inline int cpuid_maxphyaddr(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index d4ac4a1f8b81..c1c54a7a7735 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5416,12 +5416,19 @@ void __kvm_mmu_refresh_passthrough_bits(struct kvm_vcpu *vcpu,
 
 static inline int kvm_mmu_get_tdp_level(struct kvm_vcpu *vcpu)
 {
+	int maxpa;
+
+	if (vcpu->kvm->arch.vm_type == KVM_X86_TDX_VM)
+		maxpa = cpuid_query_maxguestphyaddr(vcpu);
+	else
+		maxpa = cpuid_maxphyaddr(vcpu);
+
 	/* tdp_root_level is architecture forced level, use it if nonzero */
 	if (tdp_root_level)
 		return tdp_root_level;
 
 	/* Use 5-level TDP if and only if it's useful/necessary. */
-	if (max_tdp_level == 5 && cpuid_maxphyaddr(vcpu) <= 48)
+	if (max_tdp_level == 5 && maxpa <= 48)
 		return 4;
 
 	return max_tdp_level;
-- 
2.43.5