[PATCH 1/3] xen: check required Xen features

From: Juergen Gross
Date: Thu Apr 22 2021 - 11:10:19 EST


Linux kernel is not supported to run on Xen versions older than 4.0.

Add tests for required Xen features always being present in Xen 4.0
and newer.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
drivers/xen/features.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)

diff --git a/drivers/xen/features.c b/drivers/xen/features.c
index 25c053b09605..60503299c9bc 100644
--- a/drivers/xen/features.c
+++ b/drivers/xen/features.c
@@ -9,13 +9,26 @@
#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_feature(f) { \
+ if (!xen_feature(f)) \
+ pr_err("Xen: feature %s not available!\n", #f); \
+ }
+
u8 xen_features[XENFEAT_NR_SUBMAPS * 32] __read_mostly;
EXPORT_SYMBOL_GPL(xen_features);

@@ -31,4 +44,9 @@ void xen_setup_features(void)
for (j = 0; j < 32; j++)
xen_features[i * 32 + j] = !!(fi.submap & 1<<j);
}
+
+ if (xen_pv_domain()) {
+ chk_feature(XENFEAT_mmu_pt_update_preserve_ad);
+ chk_feature(XENFEAT_gnttab_map_avail_bits);
+ }
}
--
2.26.2