[PATCH v7 2/7] xen/PMU: Sysfs interface for setting Xen PMU mode

From: Boris Ostrovsky
Date: Mon Aug 10 2015 - 16:37:25 EST


Set Xen's PMU mode via /sys/hypervisor/pmu/pmu_mode. Add XENPMU hypercall.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
Documentation/ABI/testing/sysfs-hypervisor-pmu | 23 +++++
arch/x86/include/asm/xen/hypercall.h | 6 ++
arch/x86/xen/Kconfig | 1 +
drivers/xen/Kconfig | 3 +
drivers/xen/sys-hypervisor.c | 136 ++++++++++++++++++++++++-
include/xen/interface/xen.h | 1 +
include/xen/interface/xenpmu.h | 59 +++++++++++
7 files changed, 228 insertions(+), 1 deletion(-)
create mode 100644 Documentation/ABI/testing/sysfs-hypervisor-pmu
create mode 100644 include/xen/interface/xenpmu.h

diff --git a/Documentation/ABI/testing/sysfs-hypervisor-pmu b/Documentation/ABI/testing/sysfs-hypervisor-pmu
new file mode 100644
index 0000000..224faa1
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-hypervisor-pmu
@@ -0,0 +1,23 @@
+What: /sys/hypervisor/pmu/pmu_mode
+Date: August 2015
+KernelVersion: 4.3
+Contact: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
+Description:
+ Describes mode that Xen's performance-monitoring unit (PMU)
+ uses. Accepted values are
+ "off" -- PMU is disabled
+ "self" -- The guest can profile itself
+ "hv" -- The guest can profile itself and, if it is
+ privileged (e.g. dom0), the hypervisor
+ "all" -- The guest can profile itself, the hypervisor
+ and all other guests. Only available to
+ privileged guests.
+
+What: /sys/hypervisor/pmu/pmu_features
+Date: August 2015
+KernelVersion: 4.3
+Contact: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
+Description:
+ 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/arch/x86/include/asm/xen/hypercall.h b/arch/x86/include/asm/xen/hypercall.h
index ca08a27..83aea80 100644
--- a/arch/x86/include/asm/xen/hypercall.h
+++ b/arch/x86/include/asm/xen/hypercall.h
@@ -465,6 +465,12 @@ HYPERVISOR_tmem_op(
return _hypercall1(int, tmem_op, op);
}

+static inline int
+HYPERVISOR_xenpmu_op(unsigned int op, void *arg)
+{
+ return _hypercall2(int, xenpmu_op, op, arg);
+}
+
static inline void
MULTI_fpu_taskswitch(struct multicall_entry *mcl, int set)
{
diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
index e88fda8..049cdda 100644
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -7,6 +7,7 @@ config XEN
depends on PARAVIRT
select PARAVIRT_CLOCK
select XEN_HAVE_PVMMU
+ select XEN_HAVE_VPMU
depends on X86_64 || (X86_32 && X86_PAE)
depends on X86_TSC
help
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 9367604..73708ac 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -288,4 +288,7 @@ config XEN_SYMS
Exports hypervisor symbols (along with their types and addresses) via
/proc/xen/xensyms file, similar to /proc/kallsyms

+config XEN_HAVE_VPMU
+ bool
+
endmenu
diff --git a/drivers/xen/sys-hypervisor.c b/drivers/xen/sys-hypervisor.c
index 96453f8..0907275 100644
--- a/drivers/xen/sys-hypervisor.c
+++ b/drivers/xen/sys-hypervisor.c
@@ -20,6 +20,9 @@
#include <xen/xenbus.h>
#include <xen/interface/xen.h>
#include <xen/interface/version.h>
+#ifdef CONFIG_XEN_HAVE_VPMU
+#include <xen/interface/xenpmu.h>
+#endif

#define HYPERVISOR_ATTR_RO(_name) \
static struct hyp_sysfs_attr _name##_attr = __ATTR_RO(_name)
@@ -368,6 +371,126 @@ static void xen_properties_destroy(void)
sysfs_remove_group(hypervisor_kobj, &xen_properties_group);
}

+#ifdef CONFIG_XEN_HAVE_VPMU
+struct pmu_mode {
+ const char *name;
+ uint32_t mode;
+};
+
+struct pmu_mode pmu_modes[] = {
+ {"off", XENPMU_MODE_OFF},
+ {"self", XENPMU_MODE_SELF},
+ {"hv", XENPMU_MODE_HV},
+ {"all", XENPMU_MODE_ALL}
+};
+
+static ssize_t pmu_mode_store(struct hyp_sysfs_attr *attr,
+ const char *buffer, size_t len)
+{
+ int ret;
+ struct xen_pmu_params xp;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(pmu_modes); i++) {
+ if (strncmp(buffer, pmu_modes[i].name, len - 1) == 0) {
+ xp.val = pmu_modes[i].mode;
+ break;
+ }
+ }
+
+ if (i == ARRAY_SIZE(pmu_modes))
+ return -EINVAL;
+
+ xp.version.maj = XENPMU_VER_MAJ;
+ xp.version.min = XENPMU_VER_MIN;
+ ret = HYPERVISOR_xenpmu_op(XENPMU_mode_set, &xp);
+ if (ret)
+ return ret;
+
+ return len;
+}
+
+static ssize_t pmu_mode_show(struct hyp_sysfs_attr *attr, char *buffer)
+{
+ int ret;
+ struct xen_pmu_params xp;
+ int i;
+ uint32_t mode;
+
+ xp.version.maj = XENPMU_VER_MAJ;
+ xp.version.min = XENPMU_VER_MIN;
+ ret = HYPERVISOR_xenpmu_op(XENPMU_mode_get, &xp);
+ if (ret)
+ return ret;
+
+ mode = (uint32_t)xp.val;
+ for (i = 0; i < ARRAY_SIZE(pmu_modes); i++) {
+ if (mode == pmu_modes[i].mode)
+ return sprintf(buffer, "%s\n", pmu_modes[i].name);
+ }
+
+ return -EINVAL;
+}
+HYPERVISOR_ATTR_RW(pmu_mode);
+
+static ssize_t pmu_features_store(struct hyp_sysfs_attr *attr,
+ const char *buffer, size_t len)
+{
+ int ret;
+ uint32_t features;
+ struct xen_pmu_params xp;
+
+ ret = kstrtou32(buffer, 0, &features);
+ if (ret)
+ return ret;
+
+ xp.val = features;
+ xp.version.maj = XENPMU_VER_MAJ;
+ xp.version.min = XENPMU_VER_MIN;
+ ret = HYPERVISOR_xenpmu_op(XENPMU_feature_set, &xp);
+ if (ret)
+ return ret;
+
+ return len;
+}
+
+static ssize_t pmu_features_show(struct hyp_sysfs_attr *attr, char *buffer)
+{
+ int ret;
+ struct xen_pmu_params xp;
+
+ xp.version.maj = XENPMU_VER_MAJ;
+ xp.version.min = XENPMU_VER_MIN;
+ ret = HYPERVISOR_xenpmu_op(XENPMU_feature_get, &xp);
+ if (ret)
+ return ret;
+
+ return sprintf(buffer, "0x%x\n", (uint32_t)xp.val);
+}
+HYPERVISOR_ATTR_RW(pmu_features);
+
+static struct attribute *xen_pmu_attrs[] = {
+ &pmu_mode_attr.attr,
+ &pmu_features_attr.attr,
+ NULL
+};
+
+static const struct attribute_group xen_pmu_group = {
+ .name = "pmu",
+ .attrs = xen_pmu_attrs,
+};
+
+static int __init xen_pmu_init(void)
+{
+ return sysfs_create_group(hypervisor_kobj, &xen_pmu_group);
+}
+
+static void xen_pmu_destroy(void)
+{
+ sysfs_remove_group(hypervisor_kobj, &xen_pmu_group);
+}
+#endif
+
static int __init hyper_sysfs_init(void)
{
int ret;
@@ -390,7 +513,15 @@ static int __init hyper_sysfs_init(void)
ret = xen_properties_init();
if (ret)
goto prop_out;
-
+#ifdef CONFIG_XEN_HAVE_VPMU
+ if (xen_initial_domain()) {
+ ret = xen_pmu_init();
+ if (ret) {
+ xen_properties_destroy();
+ goto prop_out;
+ }
+ }
+#endif
goto out;

prop_out:
@@ -407,6 +538,9 @@ out:

static void __exit hyper_sysfs_exit(void)
{
+#ifdef CONFIG_XEN_HAVE_VPMU
+ xen_pmu_destroy();
+#endif
xen_properties_destroy();
xen_compilation_destroy();
xen_sysfs_uuid_destroy();
diff --git a/include/xen/interface/xen.h b/include/xen/interface/xen.h
index a483789..c6399a1 100644
--- a/include/xen/interface/xen.h
+++ b/include/xen/interface/xen.h
@@ -80,6 +80,7 @@
#define __HYPERVISOR_kexec_op 37
#define __HYPERVISOR_tmem_op 38
#define __HYPERVISOR_xc_reserved_op 39 /* reserved for XenClient */
+#define __HYPERVISOR_xenpmu_op 40

/* Architecture-specific hypercall definitions. */
#define __HYPERVISOR_arch_0 48
diff --git a/include/xen/interface/xenpmu.h b/include/xen/interface/xenpmu.h
new file mode 100644
index 0000000..eac1b49
--- /dev/null
+++ b/include/xen/interface/xenpmu.h
@@ -0,0 +1,59 @@
+#ifndef __XEN_PUBLIC_XENPMU_H__
+#define __XEN_PUBLIC_XENPMU_H__
+
+#include "xen.h"
+
+#define XENPMU_VER_MAJ 0
+#define XENPMU_VER_MIN 1
+
+/*
+ * ` enum neg_errnoval
+ * ` HYPERVISOR_xenpmu_op(enum xenpmu_op cmd, struct xenpmu_params *args);
+ *
+ * @cmd == XENPMU_* (PMU operation)
+ * @args == struct xenpmu_params
+ */
+/* ` enum xenpmu_op { */
+#define XENPMU_mode_get 0 /* Also used for getting PMU version */
+#define XENPMU_mode_set 1
+#define XENPMU_feature_get 2
+#define XENPMU_feature_set 3
+#define XENPMU_init 4
+#define XENPMU_finish 5
+
+/* ` } */
+
+/* Parameters structure for HYPERVISOR_xenpmu_op call */
+struct xen_pmu_params {
+ /* IN/OUT parameters */
+ struct {
+ uint32_t maj;
+ uint32_t min;
+ } version;
+ uint64_t val;
+
+ /* IN parameters */
+ uint32_t vcpu;
+ uint32_t pad;
+};
+
+/* PMU modes:
+ * - XENPMU_MODE_OFF: No PMU virtualization
+ * - XENPMU_MODE_SELF: Guests can profile themselves
+ * - XENPMU_MODE_HV: Guests can profile themselves, dom0 profiles
+ * itself and Xen
+ * - XENPMU_MODE_ALL: Only dom0 has access to VPMU and it profiles
+ * everyone: itself, the hypervisor and the guests.
+ */
+#define XENPMU_MODE_OFF 0
+#define XENPMU_MODE_SELF (1<<0)
+#define XENPMU_MODE_HV (1<<1)
+#define XENPMU_MODE_ALL (1<<2)
+
+/*
+ * PMU features:
+ * - XENPMU_FEATURE_INTEL_BTS: Intel BTS support (ignored on AMD)
+ */
+#define XENPMU_FEATURE_INTEL_BTS 1
+
+#endif /* __XEN_PUBLIC_XENPMU_H__ */
--
1.8.1.4

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