[PATCH v7 22/23] KVM: s390: arm64: Implement basic page fault handler

@@ -55,6 +55,8 @@ static int handle_hvc(struct kvm_vcpu *vcpu)
 static exit_handle_fn arm_exit_handlers[] = {
 	[0 ... ESR_ELx_EC_MAX]	= kvm_handle_unknown_ec,
 	[ESR_ELx_EC_HVC64]	= handle_hvc,
+	[ESR_ELx_EC_IABT_LOW]	= kvm_handle_guest_abort,
+	[ESR_ELx_EC_DABT_LOW]	= kvm_handle_guest_abort,
 };
 
 /*

@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/kvm_host.h>
+#include <linux/bitfield.h>
+
+#include <trace/events/kvm.h>
+
+#include <arm64/kvm_emulate.h>
+#include <arm64/sysreg.h>
+
+#include "trace.h"
+
+#define __INCL_GEN_ARM_FILE
+#include "generated/mmio.inc"
+#undef __INCL_GEN_ARM_FILE

@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kvm_host.h>
+
+#include <arm64/kvm_emulate.h>
+
+#include <faultin.h>
+
+static inline bool kvm_s390_cur_gmap_fault_is_write(struct kvm_vcpu *vcpu)
+{
+	return vcpu->arch.sae_block.hai.pic == PGM_PROTECTION ||
+	       vcpu->arch.sae_block.hai.teid.fsi == TEID_FSI_STORE;
+}
+
+/*
+ * user_mem_abort() - handle a dat fault for the gmap of a vcpu
+ *
+ * Return: 0 on success, < 0 in case of error.
+ * Context: The mm lock must not be held before calling. May sleep.
+ */
+static int user_mem_abort(struct kvm_vcpu *vcpu, gpa_t fault_ipa,
+			  struct kvm_memory_slot *slot, hva_t hva)
+{
+	struct guest_fault f = { };
+	int ret;
+
+	if (kvm_s390_cur_gmap_fault_is_write(vcpu))
+		f.write_attempt = FOLL_WRITE;
+	f.gfn = gpa_to_gfn(fault_ipa);
+
+	ret = kvm_s390_faultin_gfn(vcpu, NULL, &f);
+	if (ret <= 0)
+		return ret;
+	if (ret == PGM_ADDRESSING)
+		/*
+		 * Without the relevant sysregs we cannot do anything for now.
+		 * Go back to userspace with an error. TODO sysreg handling
+		 */
+		return -ENOEXEC;
+	KVM_BUG_ON(ret, vcpu->kvm);
+	return -EINVAL;
+}
+
+static int kvm_handle_pic(struct kvm_vcpu *vcpu, bool *translation)
+{
+	switch (kvm_vcpu_fault_pic(vcpu)) {
+	/* expected cases: */
+	case PGM_ASCE_TYPE:
+	case PGM_REGION_FIRST_TRANS:
+	case PGM_REGION_SECOND_TRANS:
+	case PGM_REGION_THIRD_TRANS:
+	case PGM_SEGMENT_TRANSLATION:
+	case PGM_PAGE_TRANSLATION:
+		*translation = true;
+		break;
+	case PGM_PROTECTION:
+		break;
+	/* unexpected cases: */
+	case 0:
+		KVM_BUG(1, vcpu->kvm, "On MMU fault path but no fault occurred");
+		return -EFAULT;
+	default:
+		KVM_BUG(1, vcpu->kvm, "Unexpected program interrupt 0x%x, TEID 0x%016lx",
+			vcpu->arch.sae_block.hai.pic, vcpu->arch.sae_block.hai.teid.val);
+		send_sig(SIGSEGV, current, 0);
+		return -EFAULT;
+	}
+
+	return 0;
+}
+
+int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
+{
+	struct kvm_memory_slot *memslot;
+	bool translation = false;
+	phys_addr_t fault_ipa;
+	unsigned long esr;
+	unsigned long hva;
+	bool write_fault;
+	bool guest_size_err;
+	bool writable;
+	bool is_iabt;
+	int ret;
+	gfn_t gfn;
+	int idx;
+
+	esr = kvm_vcpu_get_esr(vcpu);
+	fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
+	is_iabt = kvm_vcpu_trap_is_iabt(vcpu);
+	guest_size_err = vcpu->arch.sae_block.icptr == SAE_ICPTR_GUEST_ADDRESS_SIZE;
+
+	if (guest_size_err) {
+		translation = true;
+	} else {
+		ret = kvm_handle_pic(vcpu, &translation);
+		if (ret)
+			return ret;
+	}
+
+	if (translation) {
+		/*
+		 * For both cases:
+		 * Without the relevant sysregs we cannot do anything for now.
+		 * Go back to userspace with an error. TODO sysreg handling
+		 */
+		if (fault_ipa >= BIT_ULL(get_kvm_ipa_limit()))
+			return -ENOEXEC;
+
+		if (fault_ipa >= vcpu->kvm->arch.guest_phys_size)
+			return -ENOEXEC;
+	}
+
+	idx = srcu_read_lock(&vcpu->kvm->srcu);
+
+	gfn = fault_ipa >> PAGE_SHIFT;
+
+	memslot = gfn_to_memslot(vcpu->kvm, gfn);
+	hva = gfn_to_hva_memslot_prot(memslot, gfn, &writable);
+	write_fault = kvm_is_write_fault(vcpu);
+	if (kvm_is_error_hva(hva) || (write_fault && !writable)) {
+		ret = -ENOEXEC;
+		/*
+		 * The guest has put either its instructions or its page-tables
+		 * somewhere it shouldn't have. Userspace won't be able to do
+		 * anything about this (there's no syndrome for a start).
+		 *
+		 * Without the relevant sysregs we cannot do anything for now.
+		 * Go back to userspace with an error. TODO sysreg handling
+		 */
+		if (is_iabt)
+			goto out_unlock;
+
+		if (kvm_vcpu_abt_iss1tw(vcpu)) {
+			/*
+			 * Without the relevant sysregs we cannot do anything for now.
+			 * Go back to userspace with an error. TODO sysreg handling
+			 */
+			goto out_unlock;
+		}
+
+		/*
+		 * Check for a cache maintenance operation. Assume the guest is
+		 * cautious and skip instruction
+		 */
+		if (kvm_is_error_hva(hva) && kvm_vcpu_dabt_is_cm(vcpu)) {
+			kvm_incr_pc(vcpu);
+			ret = 1;
+			goto out_unlock;
+		}
+
+		/*
+		 * The IPA is reported as [MAX:12], so we need to
+		 * complement it with the bottom 12 bits from the
+		 * faulting VA. This is always 12 bits, irrespective
+		 * of the page size.
+		 */
+		fault_ipa |= kvm_vcpu_get_hfar(vcpu) & ((1 << 12) - 1);
+		ret = io_mem_abort(vcpu, fault_ipa);
+		goto out_unlock;
+	}
+
+	/* Userspace should not be able to register out-of-bounds IPAs */
+	VM_BUG_ON(fault_ipa >= vcpu->kvm->arch.guest_phys_size);
+	/*
+	 * Proper guest size faults have been injected.
+	 * In theory it's fine to have device memory higher than MSL,
+	 * even if not currently possible, but that would have been handled above.
+	 * So if we get here with a guest size intercept, we have a bug somewhere.
+	 */
+	VM_BUG_ON(guest_size_err);
+
+	ret = user_mem_abort(vcpu, fault_ipa, memslot, hva);
+	if (!ret)
+		ret = 1;
+out_unlock:
+	srcu_read_unlock(&vcpu->kvm->srcu, idx);
+	return ret;
+}

@@ -7,6 +7,30 @@
 #undef TRACE_SYSTEM
 #define TRACE_SYSTEM kvm_arm64
 
+TRACE_EVENT(kvm_mmio_nisv,
+	TP_PROTO(unsigned long vcpu_pc, unsigned long esr,
+		 unsigned long far, unsigned long ipa),
+	TP_ARGS(vcpu_pc, esr, far, ipa),
+
+	TP_STRUCT__entry(
+		__field(	unsigned long,	vcpu_pc		)
+		__field(	unsigned long,	esr		)
+		__field(	unsigned long,	far		)
+		__field(	unsigned long,	ipa		)
+	),
+
+	TP_fast_assign(
+		__entry->vcpu_pc		= vcpu_pc;
+		__entry->esr			= esr;
+		__entry->far			= far;
+		__entry->ipa			= ipa;
+	),
+
+	TP_printk("ipa %#016lx, esr %#016lx, far %#016lx, pc %#016lx",
+		  __entry->ipa, __entry->esr,
+		  __entry->far, __entry->vcpu_pc)
+);
+
 #endif /* KVM_ARM64_TRACE_KVM_H */
 
 #undef TRACE_INCLUDE_PATH