[PATCH v5 7/9] KVM: arm64: Track KVM IOCTLs and their associated KVM caps

[Fuad Tabba <tabba@google.com>]

Track KVM IOCTLs (VM IOCTLs for now), and the associated KVM capability
that enables that IOCTL. Add a function that performs the lookup.

This will be used by CoCo VM Hypervisors (e.g., pKVM) to determine
whether a particular KVM IOCTL is allowed for its VMs.

Suggested-by: Oliver Upton <oupton@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
---
 arch/arm64/include/asm/kvm_host.h | 42 +++++++++++++++++++++++++++++++
 include/uapi/linux/kvm.h          |  1 +
 2 files changed, 43 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 64302c438355..3ec2d4edd3b4 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -1652,4 +1652,46 @@ static __always_inline enum fgt_group_id __fgt_reg_to_group_id(enum vcpu_sysreg
 		p;							\
 	})
 
+/*
+ * Tracks KVM IOCTLs and their associated KVM capabilities.
+ */
+struct kvm_ioctl_cap_map {
+	unsigned int ioctl;
+	long ext;
+};
+
+/*
+ * Sorted by ioctl to allow for potential binary search,
+ * though linear scan is sufficient for this size.
+ */
+static const struct kvm_ioctl_cap_map vm_ioctl_caps[] = {
+	{ KVM_CREATE_IRQCHIP, KVM_CAP_IRQCHIP },
+	{ KVM_ARM_SET_DEVICE_ADDR, KVM_CAP_ARM_SET_DEVICE_ADDR },
+	{ KVM_ARM_MTE_COPY_TAGS, KVM_CAP_ARM_MTE },
+	{ KVM_SET_DEVICE_ATTR, KVM_CAP_DEVICE_CTRL },
+	{ KVM_GET_DEVICE_ATTR, KVM_CAP_DEVICE_CTRL },
+	{ KVM_HAS_DEVICE_ATTR, KVM_CAP_DEVICE_CTRL },
+	{ KVM_ARM_SET_COUNTER_OFFSET, KVM_CAP_COUNTER_OFFSET },
+	{ KVM_ARM_GET_REG_WRITABLE_MASKS, KVM_CAP_ARM_SUPPORTED_REG_MASK_RANGES },
+	{ KVM_ARM_PREFERRED_TARGET, KVM_CAP_CORE },
+};
+
+/*
+ * Set *ext to the capability.
+ * Return 0 if found, or -EINVAL if no IOCTL matches.
+ */
+static inline long kvm_get_cap_for_kvm_ioctl(unsigned int ioctl, long *ext)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(vm_ioctl_caps); i++) {
+		if (vm_ioctl_caps[i].ioctl == ioctl) {
+			*ext = vm_ioctl_caps[i].ext;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
 #endif /* __ARM64_KVM_HOST_H__ */
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 52f6000ab020..1f6e51234157 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -704,6 +704,7 @@ struct kvm_enable_cap {
 /*
  * Extension capability list.
  */
+#define KVM_CAP_CORE -1	/* represents core KVM capabilities */
 #define KVM_CAP_IRQCHIP	  0
 #define KVM_CAP_HLT	  1
 #define KVM_CAP_MMU_SHADOW_CACHE_CONTROL 2
-- 
2.52.0.rc1.455.g30608eb744-goog