On 7/18/2025 12:27 AM, Fuad Tabba wrote:
From: Ackerley Tng <ackerleytng@xxxxxxxxxx>
Refactor kvm_max_private_mapping_level() to accept a NULL kvm_page_fault
pointer and rename it to kvm_gmem_max_mapping_level().
The max_mapping_level x86 operation (previously private_max_mapping_level)
is designed to potentially be called without an active page fault, for
instance, when kvm_mmu_max_mapping_level() is determining the maximum
mapping level for a gfn proactively.
Allow NULL fault pointer: Modify kvm_max_private_mapping_level() to
safely handle a NULL fault argument. This aligns its interface with the
kvm_x86_ops.max_mapping_level operation it wraps, which can also be
called with NULL.
are you sure of it?
The patch 09 just added the check of fault->is_private for TDX and SEV.
Rename function to kvm_gmem_max_mapping_level(): This reinforces that
the function's scope is for guest_memfd-backed memory, which can be
either private or non-private, removing any remaining "private"
connotation from its name.
Optimize max_level checks: Introduce a check in the caller to skip
querying for max_mapping_level if the current max_level is already
PG_LEVEL_4K, as no further reduction is possible.
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Suggested-by: Sean Christoperson <seanjc@xxxxxxxxxx>
Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
Signed-off-by: Fuad Tabba <tabba@xxxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index bb925994cbc5..6bd28fda0fd3 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4467,17 +4467,13 @@ static inline u8 kvm_max_level_for_order(int order)
return PG_LEVEL_4K;
}
-static u8 kvm_max_private_mapping_level(struct kvm *kvm,
- struct kvm_page_fault *fault,
- int gmem_order)
+static u8 kvm_gmem_max_mapping_level(struct kvm *kvm, int order,
+ struct kvm_page_fault *fault)
{
- u8 max_level = fault->max_level;
u8 req_max_level;
+ u8 max_level;
- if (max_level == PG_LEVEL_4K)
- return PG_LEVEL_4K;
-
- max_level = min(kvm_max_level_for_order(gmem_order), max_level);
+ max_level = kvm_max_level_for_order(order);
if (max_level == PG_LEVEL_4K)
return PG_LEVEL_4K;
@@ -4513,7 +4509,9 @@ static int kvm_mmu_faultin_pfn_private(struct kvm_vcpu *vcpu,
}
fault->map_writable = !(fault->slot->flags & KVM_MEM_READONLY);
- fault->max_level = kvm_max_private_mapping_level(vcpu->kvm, fault, max_order);
+ if (fault->max_level >= PG_LEVEL_4K)
+ fault->max_level = kvm_gmem_max_mapping_level(vcpu->kvm,
+ max_order, fault);
I cannot understand why this change is required. In what case will
fault->max_level < PG_LEVEL_4K?
return RET_PF_CONTINUE;
}
