KVM: arm64: Kill KVM_PGTABLE_S2_NOFWB

Nobody is using this flag anymore, so remove it. This allows
some cleanup by removing stage2_has_fwb(), which is can be replaced
by a direct check on the capability.

Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20260123191637.715429-5-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>

Author: Marc Zyngier

arch/arm64/include/asm/kvm_pgtable.h

@@ -229,15 +229,12 @@ struct kvm_pgtable_mm_ops {
 
 /**
  * enum kvm_pgtable_stage2_flags - Stage-2 page-table flags.
- * @KVM_PGTABLE_S2_NOFWB:	Don't enforce Normal-WB even if the CPUs have
- *				ARM64_HAS_STAGE2_FWB.
  * @KVM_PGTABLE_S2_IDMAP:	Only use identity mappings.
  * @KVM_PGTABLE_S2_AS_S1:	Final memory attributes are that of Stage-1.
  */
 enum kvm_pgtable_stage2_flags {
-	KVM_PGTABLE_S2_NOFWB			= BIT(0),
-	KVM_PGTABLE_S2_IDMAP			= BIT(1),
-	KVM_PGTABLE_S2_AS_S1			= BIT(2),
+	KVM_PGTABLE_S2_IDMAP			= BIT(0),
+	KVM_PGTABLE_S2_AS_S1			= BIT(1),
 };
 
 /**

arch/arm64/kvm/hyp/pgtable.c

@@ -631,14 +631,6 @@ u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift)
 	return vtcr;
 }
 
-static bool stage2_has_fwb(struct kvm_pgtable *pgt)
-{
-	if (!cpus_have_final_cap(ARM64_HAS_STAGE2_FWB))
-		return false;
-
-	return !(pgt->flags & KVM_PGTABLE_S2_NOFWB);
-}
-
 void kvm_tlb_flush_vmid_range(struct kvm_s2_mmu *mmu,
 				phys_addr_t addr, size_t size)
 {
@@ -661,14 +653,13 @@ void kvm_tlb_flush_vmid_range(struct kvm_s2_mmu *mmu,
 
 #define KVM_S2_MEMATTR(pgt, attr)					\
 	({								\
+		bool __fwb = cpus_have_final_cap(ARM64_HAS_STAGE2_FWB);	\
 		kvm_pte_t __attr;					\
 									\
 		if ((pgt)->flags & KVM_PGTABLE_S2_AS_S1)		\
-			__attr = PAGE_S2_MEMATTR(AS_S1,			\
-						 stage2_has_fwb(pgt));	\
+			__attr = PAGE_S2_MEMATTR(AS_S1,	__fwb);		\
 		else							\
-			__attr = PAGE_S2_MEMATTR(attr,			\
-						 stage2_has_fwb(pgt));	\
+			__attr = PAGE_S2_MEMATTR(attr, __fwb);		\
 									\
 		__attr;							\
 	})
@@ -880,7 +871,7 @@ static bool stage2_unmap_defer_tlb_flush(struct kvm_pgtable *pgt)
 	 * system supporting FWB as the optimization is entirely
 	 * pointless when the unmap walker needs to perform CMOs.
 	 */
-	return system_supports_tlb_range() && stage2_has_fwb(pgt);
+	return system_supports_tlb_range() && cpus_have_final_cap(ARM64_HAS_STAGE2_FWB);
 }
 
 static void stage2_unmap_put_pte(const struct kvm_pgtable_visit_ctx *ctx,
@@ -1160,7 +1151,7 @@ static int stage2_unmap_walker(const struct kvm_pgtable_visit_ctx *ctx,
 		if (mm_ops->page_count(childp) != 1)
 			return 0;
 	} else if (stage2_pte_cacheable(pgt, ctx->old)) {
-		need_flush = !stage2_has_fwb(pgt);
+		need_flush = !cpus_have_final_cap(ARM64_HAS_STAGE2_FWB);
 	}
 
 	/*
@@ -1390,7 +1381,7 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size)
 		.arg	= pgt,
 	};
 
-	if (stage2_has_fwb(pgt))
+	if (cpus_have_final_cap(ARM64_HAS_STAGE2_FWB))
 		return 0;
 
 	return kvm_pgtable_walk(pgt, addr, size, &walker);