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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v3 3/8] x86: detect and initialize Intel CAT feature
On 26/03/15 12:38, Chao Peng wrote:
> Detect Intel Cache Allocation Technology(CAT) feature and store the
> cpuid information for later use. Currently only L3 cache allocation is
> supported. The L3 CAT features may vary among sockets so per-socket
> feature information is stored. The initialization can happen either at
> boot time or when CPU(s) is hot plugged after booting.
>
> Signed-off-by: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
> ---
> Changes in v3:
> * Remove num_sockets boot option instead calculate it at boot time.
> * Name hardcoded CAT cpuid leaf as PSR_CPUID_LEVEL_CAT.
> Changes in v2:
> * socket_num => num_sockets and fix several documentaion issues.
> * refactor boot line parameters parsing into standlone patch.
> * set opt_num_sockets = NR_CPUS when opt_num_sockets > NR_CPUS.
> * replace CPU_ONLINE with CPU_STARTING and integrate that into scheduling
> improvement patch.
> * reimplement get_max_socket() with cpu_to_socket();
> * cbm is still uint64 as there is a path forward for supporting long masks.
> ---
> docs/misc/xen-command-line.markdown | 13 ++++++-
> xen/arch/x86/psr.c | 75
> ++++++++++++++++++++++++++++++++++---
> xen/include/asm-x86/cpufeature.h | 1 +
> xen/include/asm-x86/psr.h | 3 ++
> 4 files changed, 85 insertions(+), 7 deletions(-)
>
> diff --git a/docs/misc/xen-command-line.markdown
> b/docs/misc/xen-command-line.markdown
> index 1dda1f0..9ad8801 100644
> --- a/docs/misc/xen-command-line.markdown
> +++ b/docs/misc/xen-command-line.markdown
> @@ -1122,9 +1122,9 @@ This option can be specified more than once (up to 8
> times at present).
> > `= <integer>`
>
> ### psr (Intel)
> -> `= List of ( cmt:<boolean> | rmid_max:<integer> )`
> +> `= List of ( cmt:<boolean> | rmid_max:<integer> | cat:<boolean> )`
>
> -> Default: `psr=cmt:0,rmid_max:255`
> +> Default: `psr=cmt:0,rmid_max:255,cat:0`
>
> Platform Shared Resource(PSR) Services. Intel Haswell and later server
> platforms offer information about the sharing of resources.
> @@ -1134,6 +1134,11 @@ Monitoring ID(RMID) is used to bind the domain to
> corresponding shared
> resource. RMID is a hardware-provided layer of abstraction between software
> and logical processors.
>
> +To use the PSR cache allocation service for a certain domain, a capacity
> +bitmasks(CBM) is used to bind the domain to corresponding shared resource.
> +CBM represents cache capacity and indicates the degree of overlap and
> isolation
> +between domains.
> +
> The following resources are available:
>
> * Cache Monitoring Technology (Haswell and later). Information regarding the
> @@ -1144,6 +1149,10 @@ The following resources are available:
> total/local memory bandwidth. Follow the same options with Cache Monitoring
> Technology.
>
> +* Cache Alllocation Technology (Broadwell and later). Information regarding
> + the cache allocation.
> + * `cat` instructs Xen to enable/disable Cache Allocation Technology.
> +
> ### reboot
> > `= t[riple] | k[bd] | a[cpi] | p[ci] | P[ower] | e[fi] | n[o] [, [w]arm |
> [c]old]`
>
> diff --git a/xen/arch/x86/psr.c b/xen/arch/x86/psr.c
> index b3b540c..5087a75 100644
> --- a/xen/arch/x86/psr.c
> +++ b/xen/arch/x86/psr.c
> @@ -19,17 +19,36 @@
> #include <asm/psr.h>
>
> #define PSR_CMT (1<<0)
> +#define PSR_CAT (1<<1)
> +
> +struct psr_cat_socket_info {
> + bool_t initialized;
> + bool_t enabled;
> + unsigned int cbm_len;
> + unsigned int cos_max;
> +};
>
> struct psr_assoc {
> uint64_t val;
> };
>
> struct psr_cmt *__read_mostly psr_cmt;
> +static struct psr_cat_socket_info *__read_mostly cat_socket_info;
> +
> static unsigned int __initdata opt_psr;
> static unsigned int __initdata opt_rmid_max = 255;
> +static unsigned int __read_mostly nr_sockets;
> static uint64_t rmid_mask;
> static DEFINE_PER_CPU(struct psr_assoc, psr_assoc);
>
> +static unsigned int get_socket_count(void)
> +{
> + unsigned int cpus_per_socket = boot_cpu_data.x86_max_cores *
> + boot_cpu_data.x86_num_siblings;
> +
> + return DIV_ROUND_UP(nr_cpu_ids, cpus_per_socket);
> +}
> +
> static void __init parse_psr_bool(char* s, char* value, char* feature, int
> bit)
> {
> if ( !strcmp(s, feature) )
> @@ -64,6 +83,7 @@ static void __init parse_psr_param(char *s)
> *val_str++ = '\0';
>
> parse_psr_bool(s, val_str, "cmt", PSR_CMT);
> + parse_psr_bool(s, val_str, "cat", PSR_CAT);
>
> if ( val_str && !strcmp(s, "rmid_max") )
> opt_rmid_max = simple_strtoul(val_str, NULL, 0);
> @@ -207,8 +227,50 @@ void psr_ctxt_switch_to(struct domain *d)
> psr_assoc_reg_write(psra, reg);
> }
>
> +static void cat_cpu_init(unsigned int cpu)
> +{
> + unsigned int eax, ebx, ecx, edx;
> + struct psr_cat_socket_info *info;
> + unsigned int socket;
> + const struct cpuinfo_x86 *c;
> +
> + socket = cpu_to_socket(cpu);
> + ASSERT(socket < nr_sockets);
> +
> + info = cat_socket_info + socket;
> +
> + /* Avoid initializing more than one times for the same socket. */
> + if ( test_and_set_bool(info->initialized) )
> + return;
> +
> + c = cpu_data + cpu;
> + if ( !cpu_has(c, X86_FEATURE_CAT) )
> + return;
This check should be before the test_and_set_bool().
> +
> + cpuid_count(PSR_CPUID_LEVEL_CAT, 0, &eax, &ebx, &ecx, &edx);
> + if ( ebx & PSR_RESOURCE_TYPE_L3 )
> + {
> + cpuid_count(PSR_CPUID_LEVEL_CAT, 1, &eax, &ebx, &ecx, &edx);
> + info->cbm_len = (eax & 0x1f) + 1;
> + info->cos_max = (edx & 0xffff);
> +
> + info->enabled = 1;
> + printk(XENLOG_DEBUG "CAT: enabled on socket %u, cos_max:%u,
> cbm_len:%u\n",
> + socket, info->cos_max, info->cbm_len);
I would bump this to INFO, at least for socket 0. Similar to CMT, a
user which has gone to the effort of enabling CAT will want some
indication in the boot log without also having to bump the logging level.
> + }
> +}
> +
> +static void __init init_psr_cat(void)
> +{
> + nr_sockets = get_socket_count();
> + cat_socket_info = xzalloc_array(struct psr_cat_socket_info, nr_sockets);
> +}
> +
> static void psr_cpu_init(unsigned int cpu)
> {
> + if ( cat_socket_info )
> + cat_cpu_init(cpu);
> +
> psr_assoc_init();
> }
>
> @@ -236,14 +298,17 @@ static int __init psr_presmp_init(void)
> if ( (opt_psr & PSR_CMT) && opt_rmid_max )
> init_psr_cmt(opt_rmid_max);
>
> - if ( psr_cmt_enabled() )
> - {
> - psr_cpu_init(smp_processor_id());
> - register_cpu_notifier(&cpu_nfb);
> - }
> + if ( opt_psr & PSR_CAT )
> + init_psr_cat();
> +
> + psr_cpu_init(smp_processor_id());
You can be certain that smp_processor_id() is 0 in a presmp_init() callback.
> +
> + if ( psr_cmt_enabled() || cat_socket_info )
> + register_cpu_notifier(&cpu_nfb);
>
> return 0;
> }
> +
Please drop this newline. (or of you wish to keep it, fold it into patch 2)
~Andrew
> presmp_initcall(psr_presmp_init);
>
> /*
> diff --git a/xen/include/asm-x86/cpufeature.h
> b/xen/include/asm-x86/cpufeature.h
> index 7963a3a..8c0f0a6 100644
> --- a/xen/include/asm-x86/cpufeature.h
> +++ b/xen/include/asm-x86/cpufeature.h
> @@ -149,6 +149,7 @@
> #define X86_FEATURE_CMT (7*32+12) /* Cache Monitoring Technology */
> #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_CAT (7*32+15) /* Cache Allocation Technology */
> #define X86_FEATURE_RDSEED (7*32+18) /* RDSEED instruction */
> #define X86_FEATURE_ADX (7*32+19) /* ADCX, ADOX instructions */
> #define X86_FEATURE_SMAP (7*32+20) /* Supervisor Mode Access Prevention
> */
> diff --git a/xen/include/asm-x86/psr.h b/xen/include/asm-x86/psr.h
> index 585350c..3bc5496 100644
> --- a/xen/include/asm-x86/psr.h
> +++ b/xen/include/asm-x86/psr.h
> @@ -18,6 +18,9 @@
>
> #include <xen/types.h>
>
> +/* CAT cpuid level */
> +#define PSR_CPUID_LEVEL_CAT 0x10
> +
> /* Resource Type Enumeration */
> #define PSR_RESOURCE_TYPE_L3 0x2
>
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