[RFC PATCH 03/16] KVM: arm64: Move SRCU-protected region of kvm_handle_guest_abort() to helper

[Sean Christopherson <seanjc@google.com>]

Move the SRCU-protected portion of the abort handler to a separate helper
in anticipation of adding "struct kvm_page_fault" to track state related
to resolving the fault.  Using a separate helper will allow making several
fields in kvm_page_fault "const", without having to do something funky
like create a temporary copy in the middle of kvm_handle_guest_abort().

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/arm64/kvm/mmu.c | 172 ++++++++++++++++++++++---------------------
 1 file changed, 88 insertions(+), 84 deletions(-)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 1e3ac283c519..de028471b9eb 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1811,82 +1811,16 @@ static void handle_access_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
 	read_unlock(&vcpu->kvm->mmu_lock);
 }
 
-/**
- * kvm_handle_guest_abort - handles all 2nd stage aborts
- * @vcpu:	the VCPU pointer
- *
- * Any abort that gets to the host is almost guaranteed to be caused by a
- * missing second stage translation table entry, which can mean that either the
- * guest simply needs more memory and we must allocate an appropriate page or it
- * can mean that the guest tried to access I/O memory, which is emulated by user
- * space. The distinction is based on the IPA causing the fault and whether this
- * memory region has been registered as standard RAM by user space.
- */
-int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
+static int __kvm_handle_guest_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
+				    unsigned long esr)
 {
 	struct kvm_s2_trans nested_trans, *nested = NULL;
-	unsigned long esr;
-	phys_addr_t fault_ipa; /* The address we faulted on */
-	phys_addr_t ipa; /* Always the IPA in the L1 guest phys space */
 	struct kvm_memory_slot *memslot;
-	unsigned long hva;
 	bool write_fault, writable;
+	unsigned long hva;
+	phys_addr_t ipa; /* Always the IPA in the L1 guest phys space */
 	gfn_t gfn;
-	int ret, idx;
-
-	/* Synchronous External Abort? */
-	if (kvm_vcpu_abt_issea(vcpu)) {
-		/*
-		 * For RAS the host kernel may handle this abort.
-		 * There is no need to pass the error into the guest.
-		 */
-		if (kvm_handle_guest_sea())
-			return kvm_inject_serror(vcpu);
-
-		return 1;
-	}
-
-	esr = kvm_vcpu_get_esr(vcpu);
-
-	/*
-	 * The fault IPA should be reliable at this point as we're not dealing
-	 * with an SEA.
-	 */
-	ipa = fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
-	if (KVM_BUG_ON(ipa == INVALID_GPA, vcpu->kvm))
-		return -EFAULT;
-
-	if (esr_fsc_is_translation_fault(esr)) {
-		/* Beyond sanitised PARange (which is the IPA limit) */
-		if (fault_ipa >= BIT_ULL(get_kvm_ipa_limit())) {
-			kvm_inject_size_fault(vcpu);
-			return 1;
-		}
-
-		/* Falls between the IPA range and the PARange? */
-		if (fault_ipa >= BIT_ULL(VTCR_EL2_IPA(vcpu->arch.hw_mmu->vtcr))) {
-			fault_ipa |= kvm_vcpu_get_hfar(vcpu) & GENMASK(11, 0);
-
-			return kvm_inject_sea(vcpu, kvm_vcpu_trap_is_iabt(vcpu),
-					      fault_ipa);
-		}
-	}
-
-	trace_kvm_guest_fault(*vcpu_pc(vcpu), kvm_vcpu_get_esr(vcpu),
-			      kvm_vcpu_get_hfar(vcpu), fault_ipa);
-
-	/* Check the stage-2 fault is trans. fault or write fault */
-	if (!esr_fsc_is_translation_fault(esr) &&
-	    !esr_fsc_is_permission_fault(esr) &&
-	    !esr_fsc_is_access_flag_fault(esr)) {
-		kvm_err("Unsupported FSC: EC=%#x xFSC=%#lx ESR_EL2=%#lx\n",
-			kvm_vcpu_trap_get_class(vcpu),
-			(unsigned long)kvm_vcpu_trap_get_fault(vcpu),
-			(unsigned long)kvm_vcpu_get_esr(vcpu));
-		return -EFAULT;
-	}
-
-	idx = srcu_read_lock(&vcpu->kvm->srcu);
+	int ret;
 
 	/*
 	 * We may have faulted on a shadow stage 2 page table if we are
@@ -1906,13 +1840,13 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
 		ret = kvm_walk_nested_s2(vcpu, fault_ipa, &nested_trans);
 		if (ret) {
 			kvm_inject_s2_fault(vcpu, kvm_s2_trans_esr(&nested_trans));
-			goto out_unlock;
+			return ret;
 		}
 
 		ret = kvm_s2_handle_perm_fault(vcpu, &nested_trans);
 		if (ret) {
 			kvm_inject_s2_fault(vcpu, kvm_s2_trans_esr(&nested_trans));
-			goto out_unlock;
+			return ret;
 		}
 
 		ipa = kvm_s2_trans_output(&nested_trans);
@@ -1935,10 +1869,8 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
 			goto out;
 		}
 
-		if (kvm_vcpu_abt_iss1tw(vcpu)) {
-			ret = kvm_inject_sea_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
-			goto out_unlock;
-		}
+		if (kvm_vcpu_abt_iss1tw(vcpu))
+			return kvm_inject_sea_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
 
 		/*
 		 * Check for a cache maintenance operation. Since we
@@ -1952,8 +1884,7 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
 		 */
 		if (kvm_is_error_hva(hva) && kvm_vcpu_dabt_is_cm(vcpu)) {
 			kvm_incr_pc(vcpu);
-			ret = 1;
-			goto out_unlock;
+			return 1;
 		}
 
 		/*
@@ -1963,8 +1894,7 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
 		 * of the page size.
 		 */
 		ipa |= kvm_vcpu_get_hfar(vcpu) & GENMASK(11, 0);
-		ret = io_mem_abort(vcpu, ipa);
-		goto out_unlock;
+		return io_mem_abort(vcpu, ipa);
 	}
 
 	/* Userspace should not be able to register out-of-bounds IPAs */
@@ -1972,8 +1902,7 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
 
 	if (esr_fsc_is_access_flag_fault(esr)) {
 		handle_access_fault(vcpu, fault_ipa);
-		ret = 1;
-		goto out_unlock;
+		return 1;
 	}
 
 	ret = user_mem_abort(vcpu, fault_ipa, nested, memslot, hva,
@@ -1983,7 +1912,82 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
 out:
 	if (ret == -ENOEXEC)
 		ret = kvm_inject_sea_iabt(vcpu, kvm_vcpu_get_hfar(vcpu));
-out_unlock:
+	return ret;
+}
+
+/**
+ * kvm_handle_guest_abort - handles all 2nd stage aborts
+ * @vcpu:	the VCPU pointer
+ *
+ * Any abort that gets to the host is almost guaranteed to be caused by a
+ * missing second stage translation table entry, which can mean that either the
+ * guest simply needs more memory and we must allocate an appropriate page or it
+ * can mean that the guest tried to access I/O memory, which is emulated by user
+ * space. The distinction is based on the IPA causing the fault and whether this
+ * memory region has been registered as standard RAM by user space.
+ */
+int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
+{
+	unsigned long esr;
+	phys_addr_t fault_ipa; /* The address we faulted on */
+	int ret, idx;
+
+	/* Synchronous External Abort? */
+	if (kvm_vcpu_abt_issea(vcpu)) {
+		/*
+		 * For RAS the host kernel may handle this abort.
+		 * There is no need to pass the error into the guest.
+		 */
+		if (kvm_handle_guest_sea())
+			return kvm_inject_serror(vcpu);
+
+		return 1;
+	}
+
+	esr = kvm_vcpu_get_esr(vcpu);
+
+	/*
+	 * The fault IPA should be reliable at this point as we're not dealing
+	 * with an SEA.
+	 */
+	fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
+	if (KVM_BUG_ON(fault_ipa == INVALID_GPA, vcpu->kvm))
+		return -EFAULT;
+
+	if (esr_fsc_is_translation_fault(esr)) {
+		/* Beyond sanitised PARange (which is the IPA limit) */
+		if (fault_ipa >= BIT_ULL(get_kvm_ipa_limit())) {
+			kvm_inject_size_fault(vcpu);
+			return 1;
+		}
+
+		/* Falls between the IPA range and the PARange? */
+		if (fault_ipa >= BIT_ULL(VTCR_EL2_IPA(vcpu->arch.hw_mmu->vtcr))) {
+			fault_ipa |= kvm_vcpu_get_hfar(vcpu) & GENMASK(11, 0);
+
+			return kvm_inject_sea(vcpu, kvm_vcpu_trap_is_iabt(vcpu),
+					      fault_ipa);
+		}
+	}
+
+	trace_kvm_guest_fault(*vcpu_pc(vcpu), kvm_vcpu_get_esr(vcpu),
+			      kvm_vcpu_get_hfar(vcpu), fault_ipa);
+
+	/* Check the stage-2 fault is trans. fault or write fault */
+	if (!esr_fsc_is_translation_fault(esr) &&
+	    !esr_fsc_is_permission_fault(esr) &&
+	    !esr_fsc_is_access_flag_fault(esr)) {
+		kvm_err("Unsupported FSC: EC=%#x xFSC=%#lx ESR_EL2=%#lx\n",
+			kvm_vcpu_trap_get_class(vcpu),
+			(unsigned long)kvm_vcpu_trap_get_fault(vcpu),
+			(unsigned long)kvm_vcpu_get_esr(vcpu));
+		return -EFAULT;
+	}
+
+	idx = srcu_read_lock(&vcpu->kvm->srcu);
+
+	ret = __kvm_handle_guest_abort(vcpu, fault_ipa, esr);
+
 	srcu_read_unlock(&vcpu->kvm->srcu, idx);
 	return ret;
 }
-- 
2.51.0.261.g7ce5a0a67e-goog