xen: add sysfs node for guest type

Currently there is no reliable user interface inside a Xen guest to
determine its type (e.g. HVM, PV or PVH). Instead of letting user mode
try to determine this by various rather hacky mechanisms (parsing of
boot messages before they are gone, trying to make use of known subtle
differences in behavior of some instructions), add a sysfs node
/sys/hypervisor/guest_type to explicitly deliver this information as
it is known to the kernel.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

diff --git a/Documentation/ABI/testing/sysfs-hypervisor-pmu b/Documentation/ABI/testing/sysfs-hypervisor-xen
similarity index 67%
rename from Documentation/ABI/testing/sysfs-hypervisor-pmu
rename to Documentation/ABI/testing/sysfs-hypervisor-xen
index 224faa105e187920e789849ea2399a0dce767566..c0edb3fdd6ebe87d453315a8c6702606a8c2ac7e 100644 (file)
--- a/Documentation/ABI/testing/sysfs-hypervisor-pmu
+++ b/Documentation/ABI/testing/sysfs-hypervisor-xen
@@ -1,8 +1,19 @@
+What:          /sys/hypervisor/guest_type
+Date:          May 2017
+KernelVersion: 4.13
+Contact:       xen-devel@lists.xenproject.org
+Description:   If running under Xen:
+               Type of guest:
+               "Xen": standard guest type on arm
+               "HVM": fully virtualized guest (x86)
+               "PV": paravirtualized guest (x86)
+               "PVH": fully virtualized guest without legacy emulation (x86)
+
 What:          /sys/hypervisor/pmu/pmu_mode
 Date:          August 2015
 KernelVersion: 4.3
 Contact:       Boris Ostrovsky <boris.ostrovsky@oracle.com>
-Description:
+Description:   If running under Xen:
                Describes mode that Xen's performance-monitoring unit (PMU)
                uses. Accepted values are
                        "off"  -- PMU is disabled
@@ -17,7 +28,7 @@ What:           /sys/hypervisor/pmu/pmu_features
 Date:           August 2015
 KernelVersion:  4.3
 Contact:        Boris Ostrovsky <boris.ostrovsky@oracle.com>
-Description:
+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

diff --git a/MAINTAINERS b/MAINTAINERS
index 730245ac2c1840ed365d1a69c7c2b2c4ee1ac0f2..c3ce334414e9ec8d2ee51d0b2824da4074ea4d45 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13984,7 +13984,7 @@ F:      arch/x86/include/asm/xen/
 F:     include/xen/
 F:     include/uapi/xen/
 F:     Documentation/ABI/stable/sysfs-hypervisor-xen
-F:     Documentation/ABI/testing/sysfs-hypervisor-pmu
+F:     Documentation/ABI/testing/sysfs-hypervisor-xen
 
 XEN HYPERVISOR ARM
 M:     Stefano Stabellini <sstabellini@kernel.org>

diff --git a/drivers/xen/sys-hypervisor.c b/drivers/xen/sys-hypervisor.c
index 84106f9c456cd14a3798fd72893b05f1042f3873..2f78f84a31e90649ee9be7500795fa5f8de54d5f 100644 (file)
--- a/drivers/xen/sys-hypervisor.c
+++ b/drivers/xen/sys-hypervisor.c
@@ -50,6 +50,35 @@ static int __init xen_sysfs_type_init(void)
        return sysfs_create_file(hypervisor_kobj, &type_attr.attr);
 }
 
+static ssize_t guest_type_show(struct hyp_sysfs_attr *attr, char *buffer)
+{
+       const char *type;
+
+       switch (xen_domain_type) {
+       case XEN_NATIVE:
+               /* ARM only. */
+               type = "Xen";
+               break;
+       case XEN_PV_DOMAIN:
+               type = "PV";
+               break;
+       case XEN_HVM_DOMAIN:
+               type = xen_pvh_domain() ? "PVH" : "HVM";
+               break;
+       default:
+               return -EINVAL;
+       }
+
+       return sprintf(buffer, "%s\n", type);
+}
+
+HYPERVISOR_ATTR_RO(guest_type);
+
+static int __init xen_sysfs_guest_type_init(void)
+{
+       return sysfs_create_file(hypervisor_kobj, &guest_type_attr.attr);
+}
+
 /* xen version attributes */
 static ssize_t major_show(struct hyp_sysfs_attr *attr, char *buffer)
 {
@@ -471,6 +500,9 @@ static int __init hyper_sysfs_init(void)
        ret = xen_sysfs_type_init();
        if (ret)
                goto out;
+       ret = xen_sysfs_guest_type_init();
+       if (ret)
+               goto guest_type_out;
        ret = xen_sysfs_version_init();
        if (ret)
                goto version_out;
@@ -502,6 +534,8 @@ uuid_out:
 comp_out:
        sysfs_remove_group(hypervisor_kobj, &version_group);
 version_out:
+       sysfs_remove_file(hypervisor_kobj, &guest_type_attr.attr);
+guest_type_out:
        sysfs_remove_file(hypervisor_kobj, &type_attr.attr);
 out:
        return ret;