KVM: arm64: Reject VM creation when the default IPA size is unsupported

1/1

---
 Documentation/virt/kvm/api.txt |  3 +++
 arch/arm64/kvm/reset.c         | 11 ++++++++---
 2 files changed, 11 insertions(+), 3 deletions(-)
index 7064efd3b5ea..fd22224853e5 100644
@@ -172,6 +172,9 @@ is dependent on the CPU capability and the kernel configuration. The limit can
 be retrieved using KVM_CAP_ARM_VM_IPA_SIZE of the KVM_CHECK_EXTENSION
 ioctl() at run-time.
 
+Creation of the VM will fail if the requested IPA size (whether it is
+implicit or explicit) is unsupported on the host.
+
 Please note that configuring the IPA size does not affect the capability
 exposed by the guest CPUs in ID_AA64MMFR0_EL1[PARange]. It only affects
 size of the address translated by the stage2 level (guest physical to

index 784d485218ca..a3105ae464be 100644
@@ -378,10 +378,10 @@ void kvm_set_ipa_limit(void)
 		pr_info("kvm: Limiting the IPA size due to kernel %s Address limit\n",
 			(va_max < pa_max) ? "Virtual" : "Physical");
 
-	WARN(ipa_max < KVM_PHYS_SHIFT,
-	     "KVM IPA limit (%d bit) is smaller than default size\n", ipa_max);
 	kvm_ipa_limit = ipa_max;
-	kvm_info("IPA Size Limit: %dbits\n", kvm_ipa_limit);
+	kvm_info("IPA Size Limit: %d bits%s\n", kvm_ipa_limit,
+		 ((kvm_ipa_limit < KVM_PHYS_SHIFT) ?
+		  " (Reduced IPA size, limited VM/VMM compatibility)" : ""));
 }
 
 /*

@@ -408,6 +408,11 @@ int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type)
 			return -EINVAL;
 	} else {
 		phys_shift = KVM_PHYS_SHIFT;
+		if (phys_shift > kvm_ipa_limit) {
+			pr_warn_once("%s using unsupported default IPA limit, upgrade your VMM\n",
+				     current->comm);
+			return -EINVAL;
+		}
 	}
 
 	parange = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1) & 7;

2.29.2

_______________________________________________
kvmarm mailing list
[email protected]
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
---
 Documentation/virt/kvm/api.txt |    3 +++
 arch/arm64/kvm/reset.c         |   11 ++++++++---
 2 files changed, 11 insertions(+), 3 deletions(-)
@@ -172,6 +172,9 @@ is dependent on the CPU capability and t
 be retrieved using KVM_CAP_ARM_VM_IPA_SIZE of the KVM_CHECK_EXTENSION
 ioctl() at run-time.
 
+Creation of the VM will fail if the requested IPA size (whether it is
+implicit or explicit) is unsupported on the host.
+
 Please note that configuring the IPA size does not affect the capability
 exposed by the guest CPUs in ID_AA64MMFR0_EL1[PARange]. It only affects
 size of the address translated by the stage2 level (guest physical to

@@ -378,10 +378,10 @@ void kvm_set_ipa_limit(void)
 		pr_info("kvm: Limiting the IPA size due to kernel %s Address limit\n",
 			(va_max < pa_max) ? "Virtual" : "Physical");
 
-	WARN(ipa_max < KVM_PHYS_SHIFT,
-	     "KVM IPA limit (%d bit) is smaller than default size\n", ipa_max);
 	kvm_ipa_limit = ipa_max;
-	kvm_info("IPA Size Limit: %dbits\n", kvm_ipa_limit);
+	kvm_info("IPA Size Limit: %d bits%s\n", kvm_ipa_limit,
+		 ((kvm_ipa_limit < KVM_PHYS_SHIFT) ?
+		  " (Reduced IPA size, limited VM/VMM compatibility)" : ""));
 }
 
 /*

@@ -408,6 +408,11 @@ int kvm_arm_setup_stage2(struct kvm *kvm
 			return -EINVAL;
 	} else {
 		phys_shift = KVM_PHYS_SHIFT;
+		if (phys_shift > kvm_ipa_limit) {
+			pr_warn_once("%s using unsupported default IPA limit, upgrade your VMM\n",
+				     current->comm);
+			return -EINVAL;
+		}
 	}
 
 	parange = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1) & 7;
