1 files changed, 52 insertions, 0 deletions
diff --git a/drivers/xen/features.c b/drivers/xen/features.c
new file mode 100644
index 000000000..87f1828d4
--- /dev/null
+++ b/drivers/xen/features.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/******************************************************************************
+ * features.c
+ *
+ * Xen feature flags.
+ *
+ * Copyright (c) 2006, Ian Campbell, XenSource Inc.
+ */
+#include <linux/types.h>
+#include <linux/cache.h>
+#include <linux/export.h>
+#include <linux/printk.h>
+
+#include <asm/xen/hypercall.h>
+
+#include <xen/xen.h>
+#include <xen/interface/xen.h>
+#include <xen/interface/version.h>
+#include <xen/features.h>
+
+/*
+ * Linux kernel expects at least Xen 4.0.
+ *
+ * Assume some features to be available for that reason (depending on guest
+ * mode, of course).
+ */
+#define chk_required_feature(f) {					\
+		if (!xen_feature(f))					\
+			panic("Xen: feature %s not available!\n", #f);	\
+	}
+
+u8 xen_features[XENFEAT_NR_SUBMAPS * 32] __read_mostly;
+EXPORT_SYMBOL_GPL(xen_features);
+
+void xen_setup_features(void)
+{
+	struct xen_feature_info fi;
+	int i, j;
+
+	for (i = 0; i < XENFEAT_NR_SUBMAPS; i++) {
+		fi.submap_idx = i;
+		if (HYPERVISOR_xen_version(XENVER_get_features, &fi) < 0)
+			break;
+		for (j = 0; j < 32; j++)
+			xen_features[i * 32 + j] = !!(fi.submap & 1U << j);
+	}
+
+	if (xen_pv_domain()) {
+		chk_required_feature(XENFEAT_mmu_pt_update_preserve_ad);
+		chk_required_feature(XENFEAT_gnttab_map_avail_bits);
+	}
+}