[PATCH 23/25] KVM: x86/mmu: Taking guest pa into consideration when calculate tdp level

Rick Edgecombe
2024-08-12T22:48:49Z

From: Xiaoyao Li <xiaoyao.li@intel.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@intel.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
uAPI breakout v1:
- New patch
---
arch/x86/kvm/cpuid.c | 14 ++++++++++++++
arch/x86/kvm/cpuid.h | 1 +
arch/x86/kvm/mmu/mmu.c | 10 +++++++++-
3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 499479c769d8..ebebff0dbd3b 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -423,6 +423,20 @@ 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 5cc13d1b7991..2db458e4c450 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -39,6 +39,7 @@ bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx,
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 3a00bf062a46..694edcb7ef46 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5440,12 +5440,20 @@ void __kvm_mmu_refresh_passthrough_bits(struct kvm_vcpu *vcpu,

static inline int kvm_mmu_get_tdp_level(struct kvm_vcpu *vcpu)
{
+ int maxpa = 0;
+
+ if (vcpu->kvm->arch.vm_type == KVM_X86_TDX_VM)
+ maxpa = cpuid_query_maxguestphyaddr(vcpu);
+
+ if (!maxpa)
+ 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;
--
2.34.1