[PATCH] x86: Report Intel platform_id in /proc/cpuinfo

[PATCH] x86: Report Intel platform_id in /proc/cpuinfo

[Andi Kleen]

From: Andi Kleen <ak@linux.intel.com>

We have a need to distinguish systems based on their platform ID.
For example this is useful to distinguish systems with L4 cache
versus ones without.

There is a 3 bit identifier (also called processor flags) in
the IA32_PLATFORM_ID MSR that can give a more fine grained
identification of the CPU than just the model number/stepping.

IA32_PLATFORM_ID is architectural.

The MSR can be also accessed through /dev/cpu/*/msr, but that
requires root and is awkward.

The patch moves the reading of PLATFORM_INFO from the
(late) microcode driver code into the main intel CPU initialization
path and then also prints it in /proc/cpuinfo

v2: Handle 0 platform_id. Fix commit message.
v3: Move some code to cpu/intel.c
v4: Update description too.
Cc: hmh@hmh.eng.br
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 arch/x86/include/asm/processor.h      | 2 ++
 arch/x86/kernel/cpu/intel.c           | 9 +++++++++
 arch/x86/kernel/cpu/microcode/intel.c | 8 ++------
 arch/x86/kernel/cpu/proc.c            | 2 ++
 4 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 63def9537a2d..c1313b3f3e59 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -135,6 +135,8 @@ struct cpuinfo_x86 {
 	/* Index into per_cpu list: */
 	u16			cpu_index;
 	u32			microcode;
+	u32			platform_id;
+	u8			has_platform_id;
 };
 
 #define X86_VENDOR_INTEL	0
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index fcd484d2bb03..b9f139716636 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -210,6 +210,15 @@ static void early_init_intel(struct cpuinfo_x86 *c)
 			c->x86_coreid_bits = get_count_order((ebx >> 16) & 0xff);
 	}
 
+	if ((c->x86_model >= 5) || (c->x86 > 6)) {
+		unsigned val[2];
+
+		/* get processor flags from MSR 0x17 */
+		rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
+		c->platform_id = (val[1] >> 18) & 7;
+		c->has_platform_id = true;
+	}
+
 	check_mpx_erratum(c);
 }
 
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index cdc0deab00c9..fab07e49192e 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -855,17 +855,13 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 {
 	static struct cpu_signature prev;
 	struct cpuinfo_x86 *c = &cpu_data(cpu_num);
-	unsigned int val[2];
 
 	memset(csig, 0, sizeof(*csig));
 
 	csig->sig = cpuid_eax(0x00000001);
 
-	if ((c->x86_model >= 5) || (c->x86 > 6)) {
-		/* get processor flags from MSR 0x17 */
-		rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
-		csig->pf = 1 << ((val[1] >> 18) & 7);
-	}
+	if (c->has_platform_id)
+		csig->pf = 1 << c->platform_id;
 
 	csig->rev = c->microcode;
 
diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
index 18ca99f2798b..5345d50ed709 100644
--- a/arch/x86/kernel/cpu/proc.c
+++ b/arch/x86/kernel/cpu/proc.c
@@ -76,6 +76,8 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 		seq_puts(m, "stepping\t: unknown\n");
 	if (c->microcode)
 		seq_printf(m, "microcode\t: 0x%x\n", c->microcode);
+	if (c->has_platform_id)
+		seq_printf(m, "platform_id\t: %d\n", c->platform_id);
 
 	if (cpu_has(c, X86_FEATURE_TSC)) {
 		unsigned int freq = cpufreq_quick_get(cpu);
-- 
2.5.5

[PATCH] x86: Report Intel platform_id in /proc/cpuinfo

[Andi Kleen]

From: Andi Kleen <ak@linux.intel.com>

We have a need to distinguish systems based on their platform ID.
For example this is useful to distinguish systems with L4 cache
versus ones without.

There is a 3 bit identifier (also called processor flags) in
the IA32_PLATFORM_ID MSR that can give a more fine grained
identification of the CPU than just the model number/stepping.

IA32_PLATFORM_ID is architectural.

The MSR can be also accessed through /dev/cpu/*/msr, but that
requires root and is awkward.

The patch moves the reading of PLATFORM_INFO from the
(late) microcode driver code into the main intel CPU initialization
path and then also prints it in /proc/cpuinfo

v2: Handle 0 platform_id. Fix commit message.
v3: Move some code to cpu/intel.c
v4: Update description too.
v5: Move msr probe code out of line to workaround potential gcc 6 bug.
This fixes booting on all 0day systems.
Cc: hmh@hmh.eng.br
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 arch/x86/include/asm/processor.h      |  2 ++
 arch/x86/kernel/cpu/intel.c           | 15 +++++++++++++++
 arch/x86/kernel/cpu/microcode/intel.c |  8 ++------
 arch/x86/kernel/cpu/proc.c            |  2 ++
 4 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 63def9537a2d..c1313b3f3e59 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -135,6 +135,8 @@ struct cpuinfo_x86 {
 	/* Index into per_cpu list: */
 	u16			cpu_index;
 	u32			microcode;
+	u32			platform_id;
+	u8			has_platform_id;
 };
 
 #define X86_VENDOR_INTEL	0
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index fcd484d2bb03..7da7f008cee0 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -61,6 +61,19 @@ void check_mpx_erratum(struct cpuinfo_x86 *c)
 	}
 }
 
+/* noinline to work around problem with gcc 6.2 */
+static noinline void probe_platformid(struct cpuinfo_x86 *c)
+{
+	if ((c->x86_model >= 5) || (c->x86 > 6)) {
+		unsigned val[2];
+
+		/* get processor flags from MSR 0x17 */
+		rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
+		c->platform_id = (val[1] >> 18) & 7;
+		c->has_platform_id = true;
+	}
+}
+
 static void early_init_intel(struct cpuinfo_x86 *c)
 {
 	u64 misc_enable;
@@ -211,6 +224,8 @@ static void early_init_intel(struct cpuinfo_x86 *c)
 	}
 
 	check_mpx_erratum(c);
+
+	probe_platformid(c);
 }
 
 #ifdef CONFIG_X86_32
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index cdc0deab00c9..fab07e49192e 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -855,17 +855,13 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 {
 	static struct cpu_signature prev;
 	struct cpuinfo_x86 *c = &cpu_data(cpu_num);
-	unsigned int val[2];
 
 	memset(csig, 0, sizeof(*csig));
 
 	csig->sig = cpuid_eax(0x00000001);
 
-	if ((c->x86_model >= 5) || (c->x86 > 6)) {
-		/* get processor flags from MSR 0x17 */
-		rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
-		csig->pf = 1 << ((val[1] >> 18) & 7);
-	}
+	if (c->has_platform_id)
+		csig->pf = 1 << c->platform_id;
 
 	csig->rev = c->microcode;
 
diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
index 18ca99f2798b..5345d50ed709 100644
--- a/arch/x86/kernel/cpu/proc.c
+++ b/arch/x86/kernel/cpu/proc.c
@@ -76,6 +76,8 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 		seq_puts(m, "stepping\t: unknown\n");
 	if (c->microcode)
 		seq_printf(m, "microcode\t: 0x%x\n", c->microcode);
+	if (c->has_platform_id)
+		seq_printf(m, "platform_id\t: %d\n", c->platform_id);
 
 	if (cpu_has(c, X86_FEATURE_TSC)) {
 		unsigned int freq = cpufreq_quick_get(cpu);
-- 
2.5.5

[PATCH] x86: Report Intel platform_id in /proc/cpuinfo

[Andi Kleen]

From: Andi Kleen <ak@linux.intel.com>

We have a need to distinguish systems based on their platform ID.
For example this is useful to distinguish systems with L4 cache
versus ones without.

There is a 3 bit identifier (also called processor flags) in
the IA32_PLATFORM_ID MSR that can give a more fine grained
identification of the CPU than just the model number/stepping.

IA32_PLATFORM_ID is architectural.

The processor flags are already used in the microcode driver.
The MSR can be also accessed through /dev/cpu/*/msr, but that
requires root and is awkward.

This patch just exports the value retrieved by the microcode
driver in /proc/cpuinfo. If the microcode driver is disabled
it won't be shown, but that seems reasonable.

v2: Handle 0 platform_id. Fix commit message.
v3: Move some code to cpu/intel.c
Cc: hmh@hmh.eng.br
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 arch/x86/include/asm/processor.h      | 2 ++
 arch/x86/kernel/cpu/intel.c           | 9 +++++++++
 arch/x86/kernel/cpu/microcode/intel.c | 8 ++------
 arch/x86/kernel/cpu/proc.c            | 2 ++
 4 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 63def9537a2d..c1313b3f3e59 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -135,6 +135,8 @@ struct cpuinfo_x86 {
 	/* Index into per_cpu list: */
 	u16			cpu_index;
 	u32			microcode;
+	u32			platform_id;
+	u8			has_platform_id;
 };
 
 #define X86_VENDOR_INTEL	0
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index fcd484d2bb03..b9f139716636 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -210,6 +210,15 @@ static void early_init_intel(struct cpuinfo_x86 *c)
 			c->x86_coreid_bits = get_count_order((ebx >> 16) & 0xff);
 	}
 
+	if ((c->x86_model >= 5) || (c->x86 > 6)) {
+		unsigned val[2];
+
+		/* get processor flags from MSR 0x17 */
+		rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
+		c->platform_id = (val[1] >> 18) & 7;
+		c->has_platform_id = true;
+	}
+
 	check_mpx_erratum(c);
 }
 
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index cdc0deab00c9..fab07e49192e 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -855,17 +855,13 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 {
 	static struct cpu_signature prev;
 	struct cpuinfo_x86 *c = &cpu_data(cpu_num);
-	unsigned int val[2];
 
 	memset(csig, 0, sizeof(*csig));
 
 	csig->sig = cpuid_eax(0x00000001);
 
-	if ((c->x86_model >= 5) || (c->x86 > 6)) {
-		/* get processor flags from MSR 0x17 */
-		rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
-		csig->pf = 1 << ((val[1] >> 18) & 7);
-	}
+	if (c->has_platform_id)
+		csig->pf = 1 << c->platform_id;
 
 	csig->rev = c->microcode;
 
diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
index 18ca99f2798b..5345d50ed709 100644
--- a/arch/x86/kernel/cpu/proc.c
+++ b/arch/x86/kernel/cpu/proc.c
@@ -76,6 +76,8 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 		seq_puts(m, "stepping\t: unknown\n");
 	if (c->microcode)
 		seq_printf(m, "microcode\t: 0x%x\n", c->microcode);
+	if (c->has_platform_id)
+		seq_printf(m, "platform_id\t: %d\n", c->platform_id);
 
 	if (cpu_has(c, X86_FEATURE_TSC)) {
 		unsigned int freq = cpufreq_quick_get(cpu);
-- 
2.5.5

Re: [PATCH] x86: Report Intel platform_id in /proc/cpuinfo

[Thomas Gleixner]

On Thu, 22 Sep 2016, Andi Kleen wrote:
> The processor flags are already used in the microcode driver.
> The MSR can be also accessed through /dev/cpu/*/msr, but that
> requires root and is awkward.
> 
> This patch just exports the value retrieved by the microcode
> driver in /proc/cpuinfo. If the microcode driver is disabled
> it won't be shown, but that seems reasonable.

The patch is fine, but these two paragraphs are describing something else.

Thanks,

	tglx

[PATCH] x86: Report Intel platform_id in /proc/cpuinfo

[Andi Kleen]

From: Andi Kleen <ak@linux.intel.com>

We have a need to distinguish systems based on their platform ID.
For example this is useful to distinguish systems with L4 cache
versus ones without.

There is a 3 bit identifier (also called processor flags) in
the IA32_PLATFORM_ID MSR that can give a more fine grained
identification of the CPU than just the model number/stepping.

IA32_PLATFORM_ID is architectural.

The processor flags are already used in the microcode driver.
The MSR can be also accessed through /dev/cpu/*/msr, but that
requires root and is awkward.

This patch just exports the value retrieved by the microcode
driver in /proc/cpuinfo. If the microcode driver is disabled
it won't be shown, but that seems reasonable.

v2: Handle 0 platform_id. Fix commit message.
Cc: hmh@hmh.eng.br
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 arch/x86/include/asm/processor.h      | 2 ++
 arch/x86/kernel/cpu/microcode/intel.c | 2 ++
 arch/x86/kernel/cpu/proc.c            | 2 ++
 3 files changed, 6 insertions(+)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 20c11d1..270209c 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -136,6 +136,8 @@ struct cpuinfo_x86 {
 	/* Index into per_cpu list: */
 	u16			cpu_index;
 	u32			microcode;
+	u32			platform_id;
+	u8			has_platform_id;
 };
 
 #define X86_VENDOR_INTEL	0
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index ee81c54..bcd3f59 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -812,6 +812,8 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 		/* get processor flags from MSR 0x17 */
 		rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
 		csig->pf = 1 << ((val[1] >> 18) & 7);
+		cpu_data(cpu_num).platform_id = (val[1] >> 18) & 7;
+		cpu_data(cpu_num).has_platform_id = true;
 	}
 
 	csig->rev = c->microcode;
diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
index 18ca99f..5345d50 100644
--- a/arch/x86/kernel/cpu/proc.c
+++ b/arch/x86/kernel/cpu/proc.c
@@ -76,6 +76,8 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 		seq_puts(m, "stepping\t: unknown\n");
 	if (c->microcode)
 		seq_printf(m, "microcode\t: 0x%x\n", c->microcode);
+	if (c->has_platform_id)
+		seq_printf(m, "platform_id\t: %d\n", c->platform_id);
 
 	if (cpu_has(c, X86_FEATURE_TSC)) {
 		unsigned int freq = cpufreq_quick_get(cpu);
-- 
2.8.3

Re: [PATCH] x86: Report Intel platform_id in /proc/cpuinfo

[Andi Kleen]

Andi Kleen <andi@firstfloor.org> writes:

Ping! Any comments on this patch?

> From: Andi Kleen <ak@linux.intel.com>
>
> We have a need to distinguish systems based on their platform ID.
> For example this is useful to distinguish systems with L4 cache
> versus ones without.
>
> There is a 3 bit identifier (also called processor flags) in
> the IA32_PLATFORM_ID MSR that can give a more fine grained
> identification of the CPU than just the model number/stepping.
>
> IA32_PLATFORM_ID is architectural.
>
> The processor flags are already used in the microcode driver.
> The MSR can be also accessed through /dev/cpu/*/msr, but that
> requires root and is awkward.
>
> This patch just exports the value retrieved by the microcode
> driver in /proc/cpuinfo. If the microcode driver is disabled
> it won't be shown, but that seems reasonable.
>
> v2: Handle 0 platform_id. Fix commit message.
> Cc: hmh@hmh.eng.br
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
>  arch/x86/include/asm/processor.h      | 2 ++
>  arch/x86/kernel/cpu/microcode/intel.c | 2 ++
>  arch/x86/kernel/cpu/proc.c            | 2 ++
>  3 files changed, 6 insertions(+)
>
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 20c11d1..270209c 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -136,6 +136,8 @@ struct cpuinfo_x86 {
>  	/* Index into per_cpu list: */
>  	u16			cpu_index;
>  	u32			microcode;
> +	u32			platform_id;
> +	u8			has_platform_id;
>  };
>  
>  #define X86_VENDOR_INTEL	0
> diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
> index ee81c54..bcd3f59 100644
> --- a/arch/x86/kernel/cpu/microcode/intel.c
> +++ b/arch/x86/kernel/cpu/microcode/intel.c
> @@ -812,6 +812,8 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
>  		/* get processor flags from MSR 0x17 */
>  		rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
>  		csig->pf = 1 << ((val[1] >> 18) & 7);
> +		cpu_data(cpu_num).platform_id = (val[1] >> 18) & 7;
> +		cpu_data(cpu_num).has_platform_id = true;
>  	}
>  
>  	csig->rev = c->microcode;
> diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
> index 18ca99f..5345d50 100644
> --- a/arch/x86/kernel/cpu/proc.c
> +++ b/arch/x86/kernel/cpu/proc.c
> @@ -76,6 +76,8 @@ static int show_cpuinfo(struct seq_file *m, void *v)
>  		seq_puts(m, "stepping\t: unknown\n");
>  	if (c->microcode)
>  		seq_printf(m, "microcode\t: 0x%x\n", c->microcode);
> +	if (c->has_platform_id)
> +		seq_printf(m, "platform_id\t: %d\n", c->platform_id);
>  
>  	if (cpu_has(c, X86_FEATURE_TSC)) {
>  		unsigned int freq = cpufreq_quick_get(cpu);

-- 
ak@linux.intel.com -- Speaking for myself only

Re: [PATCH] x86: Report Intel platform_id in /proc/cpuinfo

[Henrique de Moraes Holschuh]

On Tue, Jun 21, 2016, at 13:05, Andi Kleen wrote:
> Andi Kleen <andi@firstfloor.org> writes:
> 
> Ping! Any comments on this patch?

Well, FWIW, it looks good enough to me.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh

Re: [PATCH] x86: Report Intel platform_id in /proc/cpuinfo

[Thomas Gleixner]

On Thu, 2 Jun 2016, Andi Kleen wrote:

Sorry for answering late. This got stuck in my backlog forever.

> diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
> index ee81c54..bcd3f59 100644
> --- a/arch/x86/kernel/cpu/microcode/intel.c
> +++ b/arch/x86/kernel/cpu/microcode/intel.c
> @@ -812,6 +812,8 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
>  		/* get processor flags from MSR 0x17 */
>  		rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
>  		csig->pf = 1 << ((val[1] >> 18) & 7);
> +		cpu_data(cpu_num).platform_id = (val[1] >> 18) & 7;
> +		cpu_data(cpu_num).has_platform_id = true;

Please move that evaluation to arch/x86/kernel/cpu/intel.c and let the
micro code driver use the information from cpu_data.

Thanks,

	tglx

[PATCH] x86: Report Intel platform_id in /proc/cpuinfo

[Andi Kleen]

From: Andi Kleen <ak@linux.intel.com>

We have a need to distinguish systems based on their platform ID.
For example this is useful to distinguish systems with L4 cache
versus ones without.

There is a 5 bit identifier (also called processor flags) in
the IA32_PLATFORM_ID MSR that can give a more fine grained
identification of the CPU than just the model number/stepping.

IA32_PLATFORM_ID is architectural.

The processor flags are already used in the microcode driver.
The MSR can be also accessed through /dev/cpu/*/msr, but that
requires root and is awkward.

This patch just exports the value retrieved by the microcode
driver in /proc/cpuinfo. If the microcode driver is disabled
it won't be shown, but that seems reasonable.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 arch/x86/include/asm/processor.h      | 1 +
 arch/x86/kernel/cpu/microcode/intel.c | 1 +
 arch/x86/kernel/cpu/proc.c            | 2 ++
 3 files changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 20c11d1..bc4b0ef 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -136,6 +136,7 @@ struct cpuinfo_x86 {
 	/* Index into per_cpu list: */
 	u16			cpu_index;
 	u32			microcode;
+	u32			platform_id;
 };
 
 #define X86_VENDOR_INTEL	0
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index ee81c54..6244a88 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -812,6 +812,7 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 		/* get processor flags from MSR 0x17 */
 		rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
 		csig->pf = 1 << ((val[1] >> 18) & 7);
+		cpu_data(cpu_num).platform_id = (val[1] >> 18) & 7;
 	}
 
 	csig->rev = c->microcode;
diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
index 18ca99f..1c4e4f5 100644
--- a/arch/x86/kernel/cpu/proc.c
+++ b/arch/x86/kernel/cpu/proc.c
@@ -76,6 +76,8 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 		seq_puts(m, "stepping\t: unknown\n");
 	if (c->microcode)
 		seq_printf(m, "microcode\t: 0x%x\n", c->microcode);
+	if (c->platform_id)
+		seq_printf(m, "platform_id\t: %d\n", c->platform_id);
 
 	if (cpu_has(c, X86_FEATURE_TSC)) {
 		unsigned int freq = cpufreq_quick_get(cpu);
-- 
2.8.2

Re: [PATCH] x86: Report Intel platform_id in /proc/cpuinfo

[Henrique de Moraes Holschuh]

On Tue, 31 May 2016, Andi Kleen wrote:
> We have a need to distinguish systems based on their platform ID.
> For example this is useful to distinguish systems with L4 cache
> versus ones without.
> 
> There is a 5 bit identifier (also called processor flags) in

There is a 3 bit identifier...

> the IA32_PLATFORM_ID MSR that can give a more fine grained
> identification of the CPU than just the model number/stepping.
> 
> IA32_PLATFORM_ID is architectural.
> 
> The processor flags are already used in the microcode driver.
> The MSR can be also accessed through /dev/cpu/*/msr, but that
> requires root and is awkward.
> 
> This patch just exports the value retrieved by the microcode
> driver in /proc/cpuinfo. If the microcode driver is disabled
> it won't be shown, but that seems reasonable.

...

> diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
> index ee81c54..6244a88 100644
> --- a/arch/x86/kernel/cpu/microcode/intel.c
> +++ b/arch/x86/kernel/cpu/microcode/intel.c
> @@ -812,6 +812,7 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
>  		/* get processor flags from MSR 0x17 */
>  		rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
>  		csig->pf = 1 << ((val[1] >> 18) & 7);
> +		cpu_data(cpu_num).platform_id = (val[1] >> 18) & 7;

See below.  It might be better to have "cpu_data(cpu_num).platform_id =
csig->pf" instead.

> diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
> index 18ca99f..1c4e4f5 100644
> --- a/arch/x86/kernel/cpu/proc.c
> +++ b/arch/x86/kernel/cpu/proc.c
> @@ -76,6 +76,8 @@ static int show_cpuinfo(struct seq_file *m, void *v)
>  		seq_puts(m, "stepping\t: unknown\n");
>  	if (c->microcode)
>  		seq_printf(m, "microcode\t: 0x%x\n", c->microcode);
> +	if (c->platform_id)
> +		seq_printf(m, "platform_id\t: %d\n", c->platform_id);

platform_id can meaningfully be zero on Intel, and in fact it often is (just
look for output from the microcode driver that logs pf=0x1).  In those
processors, (MSR(17) >> 18 & 7) is zero, and csig->pf is 1.

May I humbly suggest using the mask "(1 << value)" notation for platform_id
as used by the microcode driver?  We already do it for csig->pf, and it has
the advantage that mask notation will never be zero (so, the field is always
non-zero where relevant).

Alterntively, the patch could be changed to always print platform_id on
Intel processors, instead of just printing it out when it is non-zero.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh

Re: [PATCH] x86: Report Intel platform_id in /proc/cpuinfo

[Andi Kleen]

On Thu, Jun 02, 2016 at 03:27:07PM -0300, Henrique de Moraes Holschuh wrote:
> On Tue, 31 May 2016, Andi Kleen wrote:
> > We have a need to distinguish systems based on their platform ID.
> > For example this is useful to distinguish systems with L4 cache
> > versus ones without.
> > 
> > There is a 5 bit identifier (also called processor flags) in
> 
> There is a 3 bit identifier...

Thanks.

> > diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
> > index ee81c54..6244a88 100644
> > --- a/arch/x86/kernel/cpu/microcode/intel.c
> > +++ b/arch/x86/kernel/cpu/microcode/intel.c
> > @@ -812,6 +812,7 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
> >  		/* get processor flags from MSR 0x17 */
> >  		rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
> >  		csig->pf = 1 << ((val[1] >> 18) & 7);
> > +		cpu_data(cpu_num).platform_id = (val[1] >> 18) & 7;
> 
> See below.  It might be better to have "cpu_data(cpu_num).platform_id =
> csig->pf" instead.

Ok.

> 
> > diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
> > index 18ca99f..1c4e4f5 100644
> > --- a/arch/x86/kernel/cpu/proc.c
> > +++ b/arch/x86/kernel/cpu/proc.c
> > @@ -76,6 +76,8 @@ static int show_cpuinfo(struct seq_file *m, void *v)
> >  		seq_puts(m, "stepping\t: unknown\n");
> >  	if (c->microcode)
> >  		seq_printf(m, "microcode\t: 0x%x\n", c->microcode);
> > +	if (c->platform_id)
> > +		seq_printf(m, "platform_id\t: %d\n", c->platform_id);
> 
> platform_id can meaningfully be zero on Intel, and in fact it often is (just
> look for output from the microcode driver that logs pf=0x1).  In those
> processors, (MSR(17) >> 18 & 7) is zero, and csig->pf is 1.
> 
> May I humbly suggest using the mask "(1 << value)" notation for platform_id
> as used by the microcode driver?  We already do it for csig->pf, and it has
> the advantage that mask notation will never be zero (so, the field is always
> non-zero where relevant).

That would be confusing because the value is used in some documents.
I would prefer to match them.

> 
> Alterntively, the patch could be changed to always print platform_id on
> Intel processors, instead of just printing it out when it is non-zero.

What I can do is to add an extra flag and print it when the flag is set,
even if it is zero.

Thanks for the review.

-Andi

[PATCH] x86: Report Intel platform_id in /proc/cpuinfo

[Andi Kleen]

From: Andi Kleen <ak@linux.intel.com>

We have a need to distinguish systems based on their platform ID.
For example this is useful to distinguish systems with L4 cache
versus ones without.

There is a 5 bit identifier (also called processor flags) in
the IA32_PLATFORM_ID MSR that can give a more fine grained
identification of the CPU than just the model number/stepping.

IA32_PLATFORM_ID is architectural.

The processor flags are already used in the microcode driver.
The MSR can be also accessed through /dev/cpu/*/msr, but that
requires root and is awkward.

This patch just exports the value retrieved by the microcode
driver in /proc/cpuinfo. If the microcode driver is disabled
it won't be shown, but that seems reasonable.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 arch/x86/include/asm/processor.h      | 1 +
 arch/x86/kernel/cpu/microcode/intel.c | 1 +
 arch/x86/kernel/cpu/proc.c            | 2 ++
 3 files changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 20c11d1..bc4b0ef 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -136,6 +136,7 @@ struct cpuinfo_x86 {
 	/* Index into per_cpu list: */
 	u16			cpu_index;
 	u32			microcode;
+	u32			platform_id;
 };
 
 #define X86_VENDOR_INTEL	0
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index ee81c54..6244a88 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -812,6 +812,7 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 		/* get processor flags from MSR 0x17 */
 		rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
 		csig->pf = 1 << ((val[1] >> 18) & 7);
+		cpu_data(cpu_num).platform_id = (val[1] >> 18) & 7;
 	}
 
 	csig->rev = c->microcode;
diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
index 18ca99f..1c4e4f5 100644
--- a/arch/x86/kernel/cpu/proc.c
+++ b/arch/x86/kernel/cpu/proc.c
@@ -76,6 +76,8 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 		seq_puts(m, "stepping\t: unknown\n");
 	if (c->microcode)
 		seq_printf(m, "microcode\t: 0x%x\n", c->microcode);
+	if (c->platform_id)
+		seq_printf(m, "platform_id\t: %d\n", c->platform_id);
 
 	if (cpu_has(c, X86_FEATURE_TSC)) {
 		unsigned int freq = cpufreq_quick_get(cpu);
-- 
2.8.1

Re: [PATCH] x86: Report Intel platform_id in /proc/cpuinfo

[Henrique de Moraes Holschuh]

On Thu, May 5, 2016, at 07:12, Andi Kleen wrote:
> We have a need to distinguish systems based on their platform ID.
> For example this is useful to distinguish systems with L4 cache
> versus ones without.

Thank you for doing this, it will be useful.

> There is a 5 bit identifier (also called processor flags) in
> the IA32_PLATFORM_ID MSR that can give a more fine grained
> identification of the CPU than just the model number/stepping.

There's a relevant typo, there.   Suggestion: "There is a 3-bit
identifier (bits 52:50, also called processor flags) in..."

> IA32_PLATFORM_ID is architectural.
> 
> The processor flags are already used in the microcode driver.
> The MSR can be also accessed through /dev/cpu/*/msr, but that
> requires root and is awkward.

The existence of /dev/cpu/*/msr is actively dangerous, except maybe
inside a VM when the hypervisor does whitelisted-only filtering of MSR
access.  That thing should either die ASAP, or to grow a processor
vendor-family-model-aware whitelist.

That said, the microcode-related platform ID bits (in microcode
processor flags mask format) are available in sysfs when the microcode
driver is loaded, at:

/sys/devices/system/cpu/cpu*/microcode/processor_flags

However, there is real value in exporting these values in /proc/cpuinfo
(it will show up in the typical debugging output, and it will all be in
one single place), so I *do* agree that we should add platform_id to
/proc/cpuinfo on Intel.

Do note we are still missing the real microcode signature, which
*cannot* be fully derived from /proc/cpuinfo contents right now, even
when you have the platform_id bits from MSR 17h, because it is missing
some bits from cpuid(1).EAX.

The last time one of these cpuid bits was not zero was, AFAIK, for the
"Pentium Overdrive Processors"... but we now have Intel x86 SoCs, and I
have seen the two "type" bits from cpuid(1).EAX refered as "SoC type" in
at least one recent Intel document (sorry, I can't remember which),
which leads me to believe they might see some reuse sooner or later.

So, might also want to add a "processor signature" field, which is the
full contents of EAX for cpuid(1).  This would also shown on AMD
processors for completeness.

Alternatively, we could add a "microcode id" or "microcode signature"
field for Intel instead of the proposed "platform_id" field.  The
microcode id field would have both the contents of cpuid(1).eax *and* "1
<< MSR 17h [52:50]", e.g. "microcode_id: 0x106a5, 0x02".

> This patch just exports the value retrieved by the microcode
> driver in /proc/cpuinfo. If the microcode driver is disabled
> it won't be shown, but that seems reasonable.

Agreed.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh