[PATCH v2 10/30] KVM: arm64: Initialize struct kvm_s2_fault completely at declaration

[Marc Zyngier <maz@kernel.org>]

From: Fuad Tabba <tabba@google.com>

Simplify the initialization of struct kvm_s2_fault in user_mem_abort().

Instead of partially initializing the struct via designated initializers
and then sequentially assigning the remaining fields (like write_fault
and topup_memcache) further down the function, evaluate those
dependencies upfront.

This allows the entire struct to be fully initialized at declaration. It
also eliminates the need for the intermediate fault_data variable and
its associated fault pointer, reducing boilerplate.

Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/mmu.c | 34 ++++++++++++++++------------------
 1 file changed, 16 insertions(+), 18 deletions(-)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index e77b0b60697f6..2b85daaa4426b 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1962,8 +1962,9 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 			  struct kvm_memory_slot *memslot, unsigned long hva,
 			  bool fault_is_perm)
 {
-	int ret = 0;
-	struct kvm_s2_fault fault_data = {
+	bool write_fault = kvm_is_write_fault(vcpu);
+	bool logging_active = memslot_is_logging(memslot);
+	struct kvm_s2_fault fault = {
 		.vcpu = vcpu,
 		.fault_ipa = fault_ipa,
 		.nested = nested,
@@ -1971,19 +1972,18 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 		.hva = hva,
 		.fault_is_perm = fault_is_perm,
 		.ipa = fault_ipa,
-		.logging_active = memslot_is_logging(memslot),
-		.force_pte = memslot_is_logging(memslot),
-		.s2_force_noncacheable = false,
+		.logging_active = logging_active,
+		.force_pte = logging_active,
 		.prot = KVM_PGTABLE_PROT_R,
+		.fault_granule = fault_is_perm ? kvm_vcpu_trap_get_perm_fault_granule(vcpu) : 0,
+		.write_fault = write_fault,
+		.exec_fault = kvm_vcpu_trap_is_exec_fault(vcpu),
+		.topup_memcache = !fault_is_perm || (logging_active && write_fault),
 	};
-	struct kvm_s2_fault *fault = &fault_data;
 	void *memcache;
+	int ret;
 
-	if (fault->fault_is_perm)
-		fault->fault_granule = kvm_vcpu_trap_get_perm_fault_granule(fault->vcpu);
-	fault->write_fault = kvm_is_write_fault(fault->vcpu);
-	fault->exec_fault = kvm_vcpu_trap_is_exec_fault(fault->vcpu);
-	VM_WARN_ON_ONCE(fault->write_fault && fault->exec_fault);
+	VM_WARN_ON_ONCE(fault.write_fault && fault.exec_fault);
 
 	/*
 	 * Permission faults just need to update the existing leaf entry,
@@ -1991,9 +1991,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	 * only exception to this is when dirty logging is enabled at runtime
 	 * and a write fault needs to collapse a block entry into a table.
 	 */
-	fault->topup_memcache = !fault->fault_is_perm ||
-				(fault->logging_active && fault->write_fault);
-	ret = prepare_mmu_memcache(fault->vcpu, fault->topup_memcache, &memcache);
+	ret = prepare_mmu_memcache(vcpu, fault.topup_memcache, &memcache);
 	if (ret)
 		return ret;
 
@@ -2001,17 +1999,17 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	 * Let's check if we will get back a huge page backed by hugetlbfs, or
 	 * get block mapping for device MMIO region.
 	 */
-	ret = kvm_s2_fault_pin_pfn(fault);
+	ret = kvm_s2_fault_pin_pfn(&fault);
 	if (ret != 1)
 		return ret;
 
-	ret = kvm_s2_fault_compute_prot(fault);
+	ret = kvm_s2_fault_compute_prot(&fault);
 	if (ret) {
-		kvm_release_page_unused(fault->page);
+		kvm_release_page_unused(fault.page);
 		return ret;
 	}
 
-	return kvm_s2_fault_map(fault, memcache);
+	return kvm_s2_fault_map(&fault, memcache);
 }
 
 /* Resolve the access fault by making the page young again. */
-- 
2.47.3