RISC-V: KVM: Check host Ssaia extension when creating AIA irqchip

The KVM user-space may create KVM AIA irqchip before checking
VCPU Ssaia extension availability so KVM AIA irqchip must fail
when host does not have Ssaia extension.

Fixes: 89d0130 ("RISC-V: KVM: Implement device interface for AIA irqchip")
Signed-off-by: Anup Patel <anup.patel@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20260120080013.2153519-4-anup.patel@oss.qualcomm.com
Signed-off-by: Anup Patel <anup@brainfault.org>

Author: avpatel

arch/riscv/kvm/aia_device.c

@@ -11,6 +11,7 @@
 #include <linux/irqchip/riscv-imsic.h>
 #include <linux/kvm_host.h>
 #include <linux/uaccess.h>
+#include <linux/cpufeature.h>
 
 static int aia_create(struct kvm_device *dev, u32 type)
 {
@@ -22,6 +23,9 @@ static int aia_create(struct kvm_device *dev, u32 type)
 	if (irqchip_in_kernel(kvm))
 		return -EEXIST;
 
+	if (!riscv_isa_extension_available(NULL, SSAIA))
+		return -ENODEV;
+
 	ret = -EBUSY;
 	if (kvm_trylock_all_vcpus(kvm))
 		return ret;