[PATCH v5 11/43] arm64: kvm: Allow passing machine type in KVM creation

From: Steven Price
Date: Fri Oct 04 2024 - 11:32:21 EST


Previously machine type was used purely for specifying the physical
address size of the guest. Reserve the higher bits to specify an ARM
specific machine type and declare a new type 'KVM_VM_TYPE_ARM_REALM'
used to create a realm guest.

Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Signed-off-by: Steven Price <steven.price@xxxxxxx>
---
arch/arm64/kvm/arm.c | 17 +++++++++++++++++
arch/arm64/kvm/mmu.c | 3 ---
include/uapi/linux/kvm.h | 19 +++++++++++++++----
3 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index bb7843349f5a..d16ba8d8bc44 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -208,6 +208,23 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
mutex_unlock(&kvm->lock);
#endif

+ if (type & ~(KVM_VM_TYPE_ARM_MASK | KVM_VM_TYPE_ARM_IPA_SIZE_MASK))
+ return -EINVAL;
+
+ switch (type & KVM_VM_TYPE_ARM_MASK) {
+ case KVM_VM_TYPE_ARM_NORMAL:
+ break;
+ case KVM_VM_TYPE_ARM_REALM:
+ kvm->arch.is_realm = true;
+ if (!kvm_is_realm(kvm)) {
+ /* Realm support unavailable */
+ return -EINVAL;
+ }
+ break;
+ default:
+ return -EINVAL;
+ }
+
kvm_init_nested(kvm);

ret = kvm_share_hyp(kvm, kvm + 1);
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index e01faf72021d..d4ef6dcf8eb7 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -873,9 +873,6 @@ static int kvm_init_ipa_range(struct kvm *kvm,
if (kvm_is_realm(kvm))
ipa_limit = kvm_realm_ipa_limit();

- if (type & ~KVM_VM_TYPE_ARM_IPA_SIZE_MASK)
- return -EINVAL;
-
phys_shift = KVM_VM_TYPE_ARM_IPA_SIZE(type);
if (is_protected_kvm_enabled()) {
phys_shift = kvm_ipa_limit;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index b3884757739d..74f256eb07d2 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -648,14 +648,25 @@ struct kvm_enable_cap {
#define KVM_S390_SIE_PAGE_OFFSET 1

/*
- * On arm64, machine type can be used to request the physical
- * address size for the VM. Bits[7-0] are reserved for the guest
- * PA size shift (i.e, log2(PA_Size)). For backward compatibility,
- * value 0 implies the default IPA size, 40bits.
+ * On arm64, machine type can be used to request both the machine type and
+ * the physical address size for the VM.
+ *
+ * Bits[11-8] are reserved for the ARM specific machine type.
+ *
+ * Bits[7-0] are reserved for the guest PA size shift (i.e, log2(PA_Size)).
+ * For backward compatibility, value 0 implies the default IPA size, 40bits.
*/
+#define KVM_VM_TYPE_ARM_SHIFT 8
+#define KVM_VM_TYPE_ARM_MASK (0xfULL << KVM_VM_TYPE_ARM_SHIFT)
+#define KVM_VM_TYPE_ARM(_type) \
+ (((_type) << KVM_VM_TYPE_ARM_SHIFT) & KVM_VM_TYPE_ARM_MASK)
+#define KVM_VM_TYPE_ARM_NORMAL KVM_VM_TYPE_ARM(0)
+#define KVM_VM_TYPE_ARM_REALM KVM_VM_TYPE_ARM(1)
+
#define KVM_VM_TYPE_ARM_IPA_SIZE_MASK 0xffULL
#define KVM_VM_TYPE_ARM_IPA_SIZE(x) \
((x) & KVM_VM_TYPE_ARM_IPA_SIZE_MASK)
+
/*
* ioctls for /dev/kvm fds:
*/
--
2.34.1