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Subject[PATCH v3 4/4] xen: add sysfs node for hypervisor build id
Date
For support of Xen hypervisor live patching the hypervisor build id is
needed. Add a node /sys/hypervisor/properties/buildid containing the
information.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
Documentation/ABI/testing/sysfs-hypervisor-xen | 11 +++++++++-
drivers/xen/sys-hypervisor.c | 29 ++++++++++++++++++++++++++
2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-hypervisor-xen b/Documentation/ABI/testing/sysfs-hypervisor-xen
index c0edb3fdd6eb..53b7b2ea7515 100644
--- a/Documentation/ABI/testing/sysfs-hypervisor-xen
+++ b/Documentation/ABI/testing/sysfs-hypervisor-xen
@@ -1,5 +1,5 @@
What: /sys/hypervisor/guest_type
-Date: May 2017
+Date: June 2017
KernelVersion: 4.13
Contact: xen-devel@lists.xenproject.org
Description: If running under Xen:
@@ -32,3 +32,12 @@ Description: If running under Xen:
Describes Xen PMU features (as an integer). A set bit indicates
that the corresponding feature is enabled. See
include/xen/interface/xenpmu.h for available features
+
+What: /sys/hypervisor/properties/buildid
+Date: June 2017
+KernelVersion: 4.13
+Contact: xen-devel@lists.xenproject.org
+Description: If running under Xen:
+ Build id of the hypervisor, needed for hypervisor live patching.
+ Might return "<denied>" in case of special security settings
+ in the hypervisor.
diff --git a/drivers/xen/sys-hypervisor.c b/drivers/xen/sys-hypervisor.c
index d641e9970d5d..92307636ed54 100644
--- a/drivers/xen/sys-hypervisor.c
+++ b/drivers/xen/sys-hypervisor.c
@@ -339,12 +339,41 @@ static ssize_t features_show(struct hyp_sysfs_attr *attr, char *buffer)

HYPERVISOR_ATTR_RO(features);

+static ssize_t buildid_show(struct hyp_sysfs_attr *attr, char *buffer)
+{
+ ssize_t ret;
+ struct xen_build_id dummy;
+ struct xen_build_id *buildid;
+
+ dummy.len = 0;
+ ret = HYPERVISOR_xen_version(XENVER_get_features, &dummy);
+ if (ret < 0) {
+ if (ret == -EPERM)
+ ret = sprintf(buffer, "<denied>");
+ return ret;
+ }
+
+ buildid = kmalloc(sizeof(*buildid) + dummy.len, GFP_KERNEL);
+ if (!buildid)
+ return -ENOMEM;
+
+ ret = HYPERVISOR_xen_version(XENVER_get_features, buildid);
+ if (ret > 0)
+ ret = sprintf(buffer, "%s", buildid->buf);
+ kfree(buildid);
+
+ return ret;
+}
+
+HYPERVISOR_ATTR_RO(buildid);
+
static struct attribute *xen_properties_attrs[] = {
&capabilities_attr.attr,
&changeset_attr.attr,
&virtual_start_attr.attr,
&pagesize_attr.attr,
&features_attr.attr,
+ &buildid_attr.attr,
NULL
};

--
2.12.3
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