Re: [PATCH v6 2/6] xen/PMU: Sysfs interface for setting Xen PMU mode

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Sun, Aug 09, 2015 at 09:31:43PM -0400, Boris Ostrovsky wrote:
> Set Xen's PMU mode via /sys/hypervisor/pmu/pmu_mode. Add XENPMU hypercall.
> 
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
>  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@oracle.com>
> +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@oracle.com>
> +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
>