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List: linux-kernel
Subject: Re: [PATCH v3 04/10] x86, amd: add accessor for number of cores per compute unit
From: Guenter Roeck <linux () roeck-us ! net>
Date: 2015-10-31 22:45:53
Message-ID: 563544A1.6060505 () roeck-us ! net
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On 10/30/2015 02:56 AM, Huang Rui wrote:
> Add an accessor function amd_get_cores_per_cu() which returns the
> number of cores per compute unit. In multiple CPUs, they always have
> the same number of cores per compute unit.
>
> In a subsequent patch, we will use this function in fam15h_power
> driver.
>
> Signed-off-by: Huang Rui <ray.huang@amd.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Ingo Molnar <mingo@kernel.org>
This patch will require an Acked-by: from an x86 maintainer.
Thanks,
Guenter
> ---
> arch/x86/include/asm/processor.h | 1 +
> arch/x86/kernel/cpu/amd.c | 19 +++++++++++++++++--
> 2 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 19577dd..831ad682 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -810,6 +810,7 @@ static inline int mpx_disable_management(void)
>
> extern u16 amd_get_nb_id(int cpu);
> extern u32 amd_get_nodes_per_socket(void);
> +extern u32 amd_get_cores_per_cu(void);
>
> static inline uint32_t hypervisor_cpuid_base(const char *sig, uint32_t leaves)
> {
> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
> index 4a70fc6..a914b1b 100644
> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> @@ -27,6 +27,9 @@
> */
> static u32 nodes_per_socket = 1;
>
> +/* cores_per_cu: stores the number of cores per compute unit */
> +static u32 cores_per_cu = 1;
> +
> static inline int rdmsrl_amd_safe(unsigned msr, unsigned long long *p)
> {
> u32 gprs[8] = { 0 };
> @@ -299,7 +302,6 @@ static int nearby_node(int apicid)
> #ifdef CONFIG_SMP
> static void amd_get_topology(struct cpuinfo_x86 *c)
> {
> - u32 cores_per_cu = 1;
> u8 node_id;
> int cpu = smp_processor_id();
>
> @@ -314,7 +316,6 @@ static void amd_get_topology(struct cpuinfo_x86 *c)
> /* get compute unit information */
> smp_num_siblings = ((ebx >> 8) & 3) + 1;
> c->compute_unit_id = ebx & 0xff;
> - cores_per_cu += ((ebx >> 8) & 3);
> } else if (cpu_has(c, X86_FEATURE_NODEID_MSR)) {
> u64 value;
>
> @@ -380,6 +381,13 @@ u32 amd_get_nodes_per_socket(void)
> }
> EXPORT_SYMBOL_GPL(amd_get_nodes_per_socket);
>
> +/* this function returns the number of cores per compute unit */
> +u32 amd_get_cores_per_cu(void)
> +{
> + return cores_per_cu;
> +}
> +EXPORT_SYMBOL_GPL(amd_get_cores_per_cu);
> +
> static void srat_detect_node(struct cpuinfo_x86 *c)
> {
> #ifdef CONFIG_NUMA
> @@ -510,6 +518,13 @@ static void bsp_init_amd(struct cpuinfo_x86 *c)
>
> if (cpu_has(c, X86_FEATURE_MWAITX))
> use_mwaitx_delay();
> +
> + if (cpu_has_topoext) {
> + u32 cpuid;
> +
> + cpuid = cpuid_ebx(0x8000001e);
> + cores_per_cu += ((cpuid >> 8) & 3);
> + }
> }
>
> static void early_init_amd(struct cpuinfo_x86 *c)
>
--
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