Re: [PATCH v15 05/11] x86: detect and initialize Platform QoS Monitoring feature

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 05/09/14 09:37, Chao Peng wrote:
> Detect platform QoS feature status and enumerate the resource types,
> one of which is to monitor the L3 cache occupancy.
>
> Also introduce a Xen command line parameter to control the QoS
> feature status.
>
> Signed-off-by: Dongxiao Xu <dongxiao.xu@intel.com>
> Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
> ---
>  docs/misc/xen-command-line.markdown |   14 +++++
>  xen/arch/x86/Makefile               |    1 +
>  xen/arch/x86/pqos.c                 |  108 +++++++++++++++++++++++++++++++++++
>  xen/arch/x86/setup.c                |    3 +
>  xen/include/asm-x86/cpufeature.h    |    1 +
>  xen/include/asm-x86/pqos.h          |   53 +++++++++++++++++
>  6 files changed, 180 insertions(+)
>  create mode 100644 xen/arch/x86/pqos.c
>  create mode 100644 xen/include/asm-x86/pqos.h
>
> diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown
> index af93e17..fcda322 100644
> --- a/docs/misc/xen-command-line.markdown
> +++ b/docs/misc/xen-command-line.markdown
> @@ -1005,6 +1005,20 @@ This option can be specified more than once (up to 8 times at present).
>  ### ple\_window
>  > `= <integer>`
>  
> +### pqos (Intel)
> +> `= List of ( pqos_monitor:<boolean> | rmid_max:<integer> )`
> +
> +> Default: `pqos=pqos_monitor:0,rmid_max:255`
> +
> +Configure platform QoS services, which are available on Intel Haswell Server
> +family and future platforms.
> +
> +`pqos` instructs Xen to enable/disable platform QoS service.
> +
> +`pqos_monitor` instructs Xen to enable/disable QoS monitoring service.
> +
> +`rmid_max` indicates the max value for rmid.
> +
>  ### reboot
>  > `= t[riple] | k[bd] | a[cpi] | p[ci] | n[o] [, [w]arm | [c]old]`
>  
> diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
> index c1e244d..3d92fd7 100644
> --- a/xen/arch/x86/Makefile
> +++ b/xen/arch/x86/Makefile
> @@ -59,6 +59,7 @@ obj-y += crash.o
>  obj-y += tboot.o
>  obj-y += hpet.o
>  obj-y += xstate.o
> +obj-y += pqos.o
>  
>  obj-$(crash_debug) += gdbstub.o
>  
> diff --git a/xen/arch/x86/pqos.c b/xen/arch/x86/pqos.c
> new file mode 100644
> index 0000000..aca9ea2
> --- /dev/null
> +++ b/xen/arch/x86/pqos.c
> @@ -0,0 +1,108 @@
> +/*
> + * pqos.c: Platform QoS related service for guest.
> + *
> + * Copyright (c) 2014, Intel Corporation
> + * Author: Dongxiao Xu <dongxiao.xu@intel.com>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + */
> +#include <xen/init.h>
> +#include <xen/cpu.h>
> +#include <asm/pqos.h>
> +
> +#define PQOS_MONITOR        (1<<0)
> +
> +struct pqos_monitor *__read_mostly pqosm = NULL;
> +static bool_t __initdata opt_pqos = 0;
> +static unsigned int __initdata opt_rmid_max = 255;
> +
> +static void __init parse_pqos_param(char *s)
> +{
> +    char *ss, *val_str;
> +
> +    do {
> +        ss = strchr(s, ',');
> +        if ( ss )
> +            *ss = '\0';
> +
> +        val_str = strchr(s, ':');
> +        if ( val_str )
> +            *val_str++ = '\0';
> +
> +        if ( !strcmp(s, "pqos_monitor")
> +             && ( !val_str || parse_bool(val_str) == 1 )) {
> +            opt_pqos &= PQOS_MONITOR;
> +        } else if ( val_str && !strcmp(s, "rmid_max") )
> +            opt_rmid_max = simple_strtoul(val_str, NULL, 0);
> +
> +        s = ss + 1;
> +    } while ( ss );
> +}
> +custom_param("pqos", parse_pqos_param);
> +
> +static void __init init_pqos_monitor(unsigned int rmid_max)
> +{
> +    unsigned int eax, ebx, ecx, edx;
> +    unsigned int rmid;
> +
> +    if ( !boot_cpu_has(X86_FEATURE_QOSM) )
> +        return;
> +
> +    cpuid_count(0xf, 0, &eax, &ebx, &ecx, &edx);
> +    if ( !edx )
> +        return;
> +
> +    pqosm = xzalloc(struct pqos_monitor);
> +    if ( !pqosm )
> +        return;
> +
> +    pqosm->qm_features = edx;
> +    pqosm->rmid_mask = ~(~0ull << get_count_order(ebx));
> +    pqosm->rmid_max = min(rmid_max, ebx);
> +
> +    if ( pqosm->qm_features & QOS_MONITOR_TYPE_L3 )
> +    {
> +        cpuid_count(0xf, 1, &eax, &ebx, &ecx, &edx);
> +        pqosm->l3m.upscaling_factor = ebx;
> +        pqosm->l3m.rmid_max = ecx;
> +        pqosm->l3m.l3_features = edx;
> +    }
> +
> +    pqosm->rmid_max = min(rmid_max, pqosm->l3m.rmid_max);
> +    BUG_ON(pqosm->rmid_max < 0xffffffff);

Given that rmid_max defaults to 255 and pqosm->rmid_max is unsigned, how
can this possibly work?

~Andrew

> +    pqosm->rmid_to_dom = xmalloc_array(domid_t, pqosm->rmid_max + 1);
> +    if ( !pqosm->rmid_to_dom )
> +    {
> +        xfree(pqosm);
> +        return;
> +    }
> +    /* Reserve RMID 0 for all domains not being monitored */
> +    pqosm->rmid_to_dom[0] = DOMID_XEN;
> +    for ( rmid = 1; rmid <= pqosm->rmid_max; rmid++ )
> +        pqosm->rmid_to_dom[rmid] = DOMID_INVALID;
> +
> +    printk(XENLOG_INFO "Platform QoS Monitoring Enabled.\n");
> +}
> +
> +void __init init_platform_qos(void)
> +{
> +    if ( opt_pqos && opt_rmid_max )
> +        init_pqos_monitor(opt_rmid_max);
> +}
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * tab-width: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
> index 6a814cd..b4ad3a6 100644
> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -49,6 +49,7 @@
>  #include <xen/cpu.h>
>  #include <asm/nmi.h>
>  #include <asm/alternative.h>
> +#include <asm/pqos.h>
>  
>  /* opt_nosmp: If true, secondary processors are ignored. */
>  static bool_t __initdata opt_nosmp;
> @@ -1440,6 +1441,8 @@ void __init noreturn __start_xen(unsigned long mbi_p)
>  
>      domain_unpause_by_systemcontroller(dom0);
>  
> +    init_platform_qos();
> +
>      reset_stack_and_jump(init_done);
>  }
>  
> diff --git a/xen/include/asm-x86/cpufeature.h b/xen/include/asm-x86/cpufeature.h
> index 8014241..eb1dd27 100644
> --- a/xen/include/asm-x86/cpufeature.h
> +++ b/xen/include/asm-x86/cpufeature.h
> @@ -148,6 +148,7 @@
>  #define X86_FEATURE_ERMS	(7*32+ 9) /* Enhanced REP MOVSB/STOSB */
>  #define X86_FEATURE_INVPCID	(7*32+10) /* Invalidate Process Context ID */
>  #define X86_FEATURE_RTM 	(7*32+11) /* Restricted Transactional Memory */
> +#define X86_FEATURE_QOSM	(7*32+12) /* Platform QoS monitoring capability */
>  #define X86_FEATURE_NO_FPU_SEL 	(7*32+13) /* FPU CS/DS stored as zero */
>  #define X86_FEATURE_MPX		(7*32+14) /* Memory Protection Extensions */
>  #define X86_FEATURE_RDSEED	(7*32+18) /* RDSEED instruction */
> diff --git a/xen/include/asm-x86/pqos.h b/xen/include/asm-x86/pqos.h
> new file mode 100644
> index 0000000..96bfdc6
> --- /dev/null
> +++ b/xen/include/asm-x86/pqos.h
> @@ -0,0 +1,53 @@
> +/*
> + * pqos.h: Platform QoS related service for guest.
> + *
> + * Copyright (c) 2014, Intel Corporation
> + * Author: Dongxiao Xu <dongxiao.xu@intel.com>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + */
> +#ifndef __ASM_PQOS_H__
> +#define __ASM_PQOS_H__
> +
> +/* QoS Resource Type Enumeration */
> +#define QOS_MONITOR_TYPE_L3            0x2
> +
> +/* L3 Monitoring Features */
> +#define L3_FEATURE_OCCUPANCY           0x1
> +
> +struct pqos_monitor_l3 {
> +    unsigned int l3_features;
> +    unsigned int upscaling_factor;
> +    unsigned int rmid_max;
> +};
> +
> +struct pqos_monitor {
> +    unsigned long rmid_mask;
> +    unsigned int rmid_max;
> +    unsigned int qm_features;
> +    domid_t *rmid_to_dom;
> +    struct pqos_monitor_l3 l3m;
> +};
> +
> +extern struct pqos_monitor *pqosm;
> +
> +void init_platform_qos(void);
> +
> +#endif /* __ASM_PQOS_H__ */
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * tab-width: 4
> + * indent-tabs-mode: nil
> + * End:
> + */