1 files changed, 124 insertions, 8 deletions

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 9a6a80c3fbe5..48d7c372a4cd 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -904,6 +904,38 @@ static int kvm_init_ipa_range(struct kvm_s2_mmu *mmu, unsigned long type)
 	return 0;
 }
 
+/*
+ * Assume that @pgt is valid and unlinked from the KVM MMU to free the
+ * page-table without taking the kvm_mmu_lock and without performing any
+ * TLB invalidations.
+ *
+ * Also, the range of addresses can be large enough to cause need_resched
+ * warnings, for instance on CONFIG_PREEMPT_NONE kernels. Hence, invoke
+ * cond_resched() periodically to prevent hogging the CPU for a long time
+ * and schedule something else, if required.
+ */
+static void stage2_destroy_range(struct kvm_pgtable *pgt, phys_addr_t addr,
+				   phys_addr_t end)
+{
+	u64 next;
+
+	do {
+		next = stage2_range_addr_end(addr, end);
+		KVM_PGT_FN(kvm_pgtable_stage2_destroy_range)(pgt, addr,
+							     next - addr);
+		if (next != end)
+			cond_resched();
+	} while (addr = next, addr != end);
+}
+
+static void kvm_stage2_destroy(struct kvm_pgtable *pgt)
+{
+	unsigned int ia_bits = VTCR_EL2_IPA(pgt->mmu->vtcr);
+
+	stage2_destroy_range(pgt, 0, BIT(ia_bits));
+	KVM_PGT_FN(kvm_pgtable_stage2_destroy_pgd)(pgt);
+}
+
 /**
  * kvm_init_stage2_mmu - Initialise a S2 MMU structure
  * @kvm:	The pointer to the KVM structure
@@ -980,7 +1012,7 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t
 	return 0;
 
 out_destroy_pgtable:
-	KVM_PGT_FN(kvm_pgtable_stage2_destroy)(pgt);
+	kvm_stage2_destroy(pgt);
 out_free_pgtable:
 	kfree(pgt);
 	return err;
@@ -1081,7 +1113,7 @@ void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu)
 	write_unlock(&kvm->mmu_lock);
 
 	if (pgt) {
-		KVM_PGT_FN(kvm_pgtable_stage2_destroy)(pgt);
+		kvm_stage2_destroy(pgt);
 		kfree(pgt);
 	}
 }
@@ -1521,6 +1553,16 @@ static void adjust_nested_fault_perms(struct kvm_s2_trans *nested,
 	*prot |= kvm_encode_nested_level(nested);
 }
 
+static void adjust_nested_exec_perms(struct kvm *kvm,
+				     struct kvm_s2_trans *nested,
+				     enum kvm_pgtable_prot *prot)
+{
+	if (!kvm_s2_trans_exec_el0(kvm, nested))
+		*prot &= ~KVM_PGTABLE_PROT_UX;
+	if (!kvm_s2_trans_exec_el1(kvm, nested))
+		*prot &= ~KVM_PGTABLE_PROT_PX;
+}
+
 #define KVM_PGTABLE_WALK_MEMABORT_FLAGS (KVM_PGTABLE_WALK_HANDLE_FAULT | KVM_PGTABLE_WALK_SHARED)
 
 static int gmem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
@@ -1572,11 +1614,12 @@ static int gmem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	if (writable)
 		prot |= KVM_PGTABLE_PROT_W;
 
-	if (exec_fault ||
-	    (cpus_have_final_cap(ARM64_HAS_CACHE_DIC) &&
-	     (!nested || kvm_s2_trans_executable(nested))))
+	if (exec_fault || cpus_have_final_cap(ARM64_HAS_CACHE_DIC))
 		prot |= KVM_PGTABLE_PROT_X;
 
+	if (nested)
+		adjust_nested_exec_perms(kvm, nested, &prot);
+
 	kvm_fault_lock(kvm);
 	if (mmu_invalidate_retry(kvm, mmu_seq)) {
 		ret = -EAGAIN;
@@ -1851,11 +1894,13 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 			prot |= KVM_PGTABLE_PROT_NORMAL_NC;
 		else
 			prot |= KVM_PGTABLE_PROT_DEVICE;
-	} else if (cpus_have_final_cap(ARM64_HAS_CACHE_DIC) &&
-		   (!nested || kvm_s2_trans_executable(nested))) {
+	} else if (cpus_have_final_cap(ARM64_HAS_CACHE_DIC)) {
 		prot |= KVM_PGTABLE_PROT_X;
 	}
 
+	if (nested)
+		adjust_nested_exec_perms(kvm, nested, &prot);
+
 	/*
 	 * Under the premise of getting a FSC_PERM fault, we just need to relax
 	 * permissions only if vma_pagesize equals fault_granule. Otherwise,
@@ -1899,8 +1944,48 @@ static void handle_access_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
 	read_unlock(&vcpu->kvm->mmu_lock);
 }
 
+/*
+ * Returns true if the SEA should be handled locally within KVM if the abort
+ * is caused by a kernel memory allocation (e.g. stage-2 table memory).
+ */
+static bool host_owns_sea(struct kvm_vcpu *vcpu, u64 esr)
+{
+	/*
+	 * Without FEAT_RAS HCR_EL2.TEA is RES0, meaning any external abort
+	 * taken from a guest EL to EL2 is due to a host-imposed access (e.g.
+	 * stage-2 PTW).
+	 */
+	if (!cpus_have_final_cap(ARM64_HAS_RAS_EXTN))
+		return true;
+
+	/* KVM owns the VNCR when the vCPU isn't in a nested context. */
+	if (is_hyp_ctxt(vcpu) && !kvm_vcpu_trap_is_iabt(vcpu) && (esr & ESR_ELx_VNCR))
+		return true;
+
+	/*
+	 * Determining if an external abort during a table walk happened at
+	 * stage-2 is only possible with S1PTW is set. Otherwise, since KVM
+	 * sets HCR_EL2.TEA, SEAs due to a stage-1 walk (i.e. accessing the
+	 * PA of the stage-1 descriptor) can reach here and are reported
+	 * with a TTW ESR value.
+	 */
+	return (esr_fsc_is_sea_ttw(esr) && (esr & ESR_ELx_S1PTW));
+}
+
 int kvm_handle_guest_sea(struct kvm_vcpu *vcpu)
 {
+	struct kvm *kvm = vcpu->kvm;
+	struct kvm_run *run = vcpu->run;
+	u64 esr = kvm_vcpu_get_esr(vcpu);
+	u64 esr_mask = ESR_ELx_EC_MASK	|
+		       ESR_ELx_IL	|
+		       ESR_ELx_FnV	|
+		       ESR_ELx_EA	|
+		       ESR_ELx_CM	|
+		       ESR_ELx_WNR	|
+		       ESR_ELx_FSC;
+	u64 ipa;
+
 	/*
 	 * Give APEI the opportunity to claim the abort before handling it
 	 * within KVM. apei_claim_sea() expects to be called with IRQs enabled.
@@ -1909,7 +1994,33 @@ int kvm_handle_guest_sea(struct kvm_vcpu *vcpu)
 	if (apei_claim_sea(NULL) == 0)
 		return 1;
 
-	return kvm_inject_serror(vcpu);
+	if (host_owns_sea(vcpu, esr) ||
+	    !test_bit(KVM_ARCH_FLAG_EXIT_SEA, &vcpu->kvm->arch.flags))
+		return kvm_inject_serror(vcpu);
+
+	/* ESR_ELx.SET is RES0 when FEAT_RAS isn't implemented. */
+	if (kvm_has_ras(kvm))
+		esr_mask |= ESR_ELx_SET_MASK;
+
+	/*
+	 * Exit to userspace, and provide faulting guest virtual and physical
+	 * addresses in case userspace wants to emulate SEA to guest by
+	 * writing to FAR_ELx and HPFAR_ELx registers.
+	 */
+	memset(&run->arm_sea, 0, sizeof(run->arm_sea));
+	run->exit_reason = KVM_EXIT_ARM_SEA;
+	run->arm_sea.esr = esr & esr_mask;
+
+	if (!(esr & ESR_ELx_FnV))
+		run->arm_sea.gva = kvm_vcpu_get_hfar(vcpu);
+
+	ipa = kvm_vcpu_get_fault_ipa(vcpu);
+	if (ipa != INVALID_GPA) {
+		run->arm_sea.flags |= KVM_EXIT_ARM_SEA_FLAG_GPA_VALID;
+		run->arm_sea.gpa = ipa;
+	}
+
+	return 0;
 }
 
 /**
@@ -1999,6 +2110,11 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
 		u32 esr;
 
 		ret = kvm_walk_nested_s2(vcpu, fault_ipa, &nested_trans);
+		if (ret == -EAGAIN) {
+			ret = 1;
+			goto out_unlock;
+		}
+
 		if (ret) {
 			esr = kvm_s2_trans_esr(&nested_trans);
 			kvm_inject_s2_fault(vcpu, esr);