[PATCH] detect Xen dom0 properly to avoid conflict with pv_on_hvm domU

[Olaf Hering]

A Xen HVM guest with PV drivers loaded has also a /proc/xen directory.
But such a guest is an ordinary PC and the special handling for dom0
breaks kdump in this environment.
Test for /proc/xen/capabilities instead and cache the result.

Also make two variables static, they are only used in this file.

Signed-off-by: Olaf Hering <olaf at aepfle.de>

---
 kexec/crashdump-xen.c |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

Index: kexec-tools-0.8.15/kexec/crashdump-xen.c
===================================================================
--- kexec-tools-0.8.15.orig/kexec/crashdump-xen.c
+++ kexec-tools-0.8.15/kexec/crashdump-xen.c
@@ -25,14 +25,19 @@ struct crash_note_info {
 	unsigned long length;
 };
 
-int xen_phys_cpus = 0;
-struct crash_note_info *xen_phys_notes;
+static int xen_phys_cpus;
+static struct crash_note_info *xen_phys_notes;
+static int is_dom0;
 
 int xen_present(void)
 {
-	struct stat buf;
-
-	return stat("/proc/xen", &buf) == 0;
+	if (!is_dom0) {
+		if (access("/proc/xen/capabilities", F_OK) == 0)
+			is_dom0 = 1;
+		else
+			is_dom0 = -1;
+	}
+	return is_dom0 > 0;
 }
 
 unsigned long xen_architecture(struct crash_elf_info *elf_info)