ANDROID: virt: gunyah: Allow host to reclaim memory provided to the guest

Introduce an ioctl, GH_VM_RECLAIM_REGION which attempts to reclaim guest
memory. If the guest hasn't relinquished the memory, an error is
returned.

Bug: 395833312
Change-Id: I005c947435f0256f6200c0d7d86eea145e1daa0a
Signed-off-by: Elliot Berman <elliot.berman@oss.qualcomm.com>

drivers/virt/gunyah/vm_mgr.c

@@ -923,6 +923,22 @@ static long gunyah_vm_ioctl(struct file *filp, unsigned int cmd,
 		r = gunyah_vm_binding_alloc(ghvm, &region, lend);
 		break;
 	}
+	case GH_VM_RECLAIM_REGION: {
+		struct gunyah_address_range range;
+
+		/* only allow owner task to remove memory */
+		if (ghvm->mm_s != current->mm)
+			return -EPERM;
+		if (copy_from_user(&range, argp, sizeof(range)))
+			return -EFAULT;
+		if (!PAGE_ALIGNED(range.size) || !PAGE_ALIGNED(range.guest_phys_addr))
+			return -EINVAL;
+
+		r = gunyah_vm_reclaim_range(ghvm,
+					    gunyah_gpa_to_gfn(range.guest_phys_addr),
+					    gunyah_gpa_to_gfn(range.size) - 1);
+		break;
+	}
 	case GUNYAH_VM_SET_BOOT_CONTEXT: {
 		struct gunyah_vm_boot_context boot_ctx;
 

include/uapi/linux/gunyah.h

@@ -387,4 +387,13 @@ struct gunyah_vm_firmware_config {
 
 #define GH_VM_ANDROID_SET_FW_CONFIG	_IOW(GH_ANDROID_IOCTL_TYPE, 0x12, \
 						struct gunyah_vm_firmware_config)
+
+struct gunyah_address_range {
+	__u64 guest_phys_addr;
+	__u64 size;
+};
+
+#define GH_VM_RECLAIM_REGION		_IOW(GH_ANDROID_IOCTL_TYPE, 0x13, \
+						struct gunyah_address_range)
+
 #endif