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xen: add sysfs node for guest type

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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>
This commit is contained in:
Juergen Gross 2017-06-14 17:12:45 +02:00
parent db98522077
commit 4a4c29c96d
3 changed files with 48 additions and 3 deletions
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15
Documentation/ABI/testing/sysfs-hypervisor-pmu → Documentation/ABI/testing/sysfs-hypervisor-xen
View file

@ -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

2
MAINTAINERS
View file

@ -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>

34
drivers/xen/sys-hypervisor.c
View file

@ -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;