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[PATCH v3 01/10] x86/resctrl: Fix min_cbm_bits for AMD

Babu Moger posted 10 patches 3 years, 7 months ago
There is a newer version of this series
[PATCH v3 01/10] x86/resctrl: Fix min_cbm_bits for AMD
Posted by Babu Moger 3 years, 7 months ago 
AMD systems support zero CBM (capacity bit mask) for L3 allocation.
That is reflected in rdt_init_res_defs_amd() by:

	r->cache.arch_has_empty_bitmaps = true;

However given the unified code in cbm_validate(), checking for:
	val == 0 && !arch_has_empty_bitmaps

is not enough because of another check in cbm_validate():

	if ((zero_bit - first_bit) < r->cache.min_cbm_bits)

The default value of r->cache.min_cbm_bits = 1.

Leading to:

	$ cd /sys/fs/resctrl
	$ mkdir foo
	$ cd foo
	$ echo L3:0=0 > schemata
          -bash: echo: write error: Invalid argument
	$ cat /sys/fs/resctrl/info/last_cmd_status
	  Need at least 1 bits in the mask

Fix the issue by initializing the min_cbm_bits to 0 for AMD. Also remove
the default setting of min_cbm_bits and initialize it separately.

After the fix
	$ cd /sys/fs/resctrl
	$ mkdir foo
	$ cd foo
	$ echo L3:0=0 > schemata
	$ cat /sys/fs/resctrl/info/last_cmd_status
	  ok

Link: https://lore.kernel.org/lkml/20220517001234.3137157-1-eranian@google.com/
Fixes: 316e7f901f5a ("x86/resctrl: Add struct rdt_cache::arch_has_{sparse, empty}_bitmaps")
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Babu Moger <babu.moger@amd.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/cpu/resctrl/core.c |    8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index bb1c3f5f60c8..a5c51a14fbce 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -66,9 +66,6 @@ struct rdt_hw_resource rdt_resources_all[] = {
 			.rid			= RDT_RESOURCE_L3,
 			.name			= "L3",
 			.cache_level		= 3,
-			.cache = {
-				.min_cbm_bits	= 1,
-			},
 			.domains		= domain_init(RDT_RESOURCE_L3),
 			.parse_ctrlval		= parse_cbm,
 			.format_str		= "%d=%0*x",
@@ -83,9 +80,6 @@ struct rdt_hw_resource rdt_resources_all[] = {
 			.rid			= RDT_RESOURCE_L2,
 			.name			= "L2",
 			.cache_level		= 2,
-			.cache = {
-				.min_cbm_bits	= 1,
-			},
 			.domains		= domain_init(RDT_RESOURCE_L2),
 			.parse_ctrlval		= parse_cbm,
 			.format_str		= "%d=%0*x",
@@ -877,6 +871,7 @@ static __init void rdt_init_res_defs_intel(void)
 			r->cache.arch_has_sparse_bitmaps = false;
 			r->cache.arch_has_empty_bitmaps = false;
 			r->cache.arch_has_per_cpu_cfg = false;
+			r->cache.min_cbm_bits = 1;
 		} else if (r->rid == RDT_RESOURCE_MBA) {
 			hw_res->msr_base = MSR_IA32_MBA_THRTL_BASE;
 			hw_res->msr_update = mba_wrmsr_intel;
@@ -897,6 +892,7 @@ static __init void rdt_init_res_defs_amd(void)
 			r->cache.arch_has_sparse_bitmaps = true;
 			r->cache.arch_has_empty_bitmaps = true;
 			r->cache.arch_has_per_cpu_cfg = true;
+			r->cache.min_cbm_bits = 0;
 		} else if (r->rid == RDT_RESOURCE_MBA) {
 			hw_res->msr_base = MSR_IA32_MBA_BW_BASE;
 			hw_res->msr_update = mba_wrmsr_amd;
Re: [PATCH v3 01/10] x86/resctrl: Fix min_cbm_bits for AMD
Posted by Reinette Chatre 3 years, 7 months ago 
Hi Babu,

On 8/22/2022 6:42 AM, Babu Moger wrote:
> AMD systems support zero CBM (capacity bit mask) for L3 allocation.
> That is reflected in rdt_init_res_defs_amd() by:
> 
> 	r->cache.arch_has_empty_bitmaps = true;
> 
> However given the unified code in cbm_validate(), checking for:
> 	val == 0 && !arch_has_empty_bitmaps
> 
> is not enough because of another check in cbm_validate():
> 
> 	if ((zero_bit - first_bit) < r->cache.min_cbm_bits)
> 
> The default value of r->cache.min_cbm_bits = 1.
> 
> Leading to:
> 
> 	$ cd /sys/fs/resctrl
> 	$ mkdir foo
> 	$ cd foo
> 	$ echo L3:0=0 > schemata
>           -bash: echo: write error: Invalid argument
> 	$ cat /sys/fs/resctrl/info/last_cmd_status
> 	  Need at least 1 bits in the mask
> 
> Fix the issue by initializing the min_cbm_bits to 0 for AMD. Also remove
> the default setting of min_cbm_bits and initialize it separately.
> 
> After the fix
> 	$ cd /sys/fs/resctrl
> 	$ mkdir foo
> 	$ cd foo
> 	$ echo L3:0=0 > schemata
> 	$ cat /sys/fs/resctrl/info/last_cmd_status
> 	  ok
> 
> Link: https://lore.kernel.org/lkml/20220517001234.3137157-1-eranian@google.com/
> Fixes: 316e7f901f5a ("x86/resctrl: Add struct rdt_cache::arch_has_{sparse, empty}_bitmaps")
> Signed-off-by: Stephane Eranian <eranian@google.com>
> Signed-off-by: Babu Moger <babu.moger@amd.com>
> Reviewed-by: Ingo Molnar <mingo@kernel.org>
> ---
>  arch/x86/kernel/cpu/resctrl/core.c |    8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
> index bb1c3f5f60c8..a5c51a14fbce 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -66,9 +66,6 @@ struct rdt_hw_resource rdt_resources_all[] = {
>  			.rid			= RDT_RESOURCE_L3,
>  			.name			= "L3",
>  			.cache_level		= 3,
> -			.cache = {
> -				.min_cbm_bits	= 1,
> -			},
>  			.domains		= domain_init(RDT_RESOURCE_L3),
>  			.parse_ctrlval		= parse_cbm,
>  			.format_str		= "%d=%0*x",
> @@ -83,9 +80,6 @@ struct rdt_hw_resource rdt_resources_all[] = {
>  			.rid			= RDT_RESOURCE_L2,
>  			.name			= "L2",
>  			.cache_level		= 2,
> -			.cache = {
> -				.min_cbm_bits	= 1,
> -			},
>  			.domains		= domain_init(RDT_RESOURCE_L2),
>  			.parse_ctrlval		= parse_cbm,
>  			.format_str		= "%d=%0*x",
> @@ -877,6 +871,7 @@ static __init void rdt_init_res_defs_intel(void)
>  			r->cache.arch_has_sparse_bitmaps = false;
>  			r->cache.arch_has_empty_bitmaps = false;
>  			r->cache.arch_has_per_cpu_cfg = false;
> +			r->cache.min_cbm_bits = 1;
>  		} else if (r->rid == RDT_RESOURCE_MBA) {
>  			hw_res->msr_base = MSR_IA32_MBA_THRTL_BASE;
>  			hw_res->msr_update = mba_wrmsr_intel;
> @@ -897,6 +892,7 @@ static __init void rdt_init_res_defs_amd(void)
>  			r->cache.arch_has_sparse_bitmaps = true;
>  			r->cache.arch_has_empty_bitmaps = true;
>  			r->cache.arch_has_per_cpu_cfg = true;
> +			r->cache.min_cbm_bits = 0;
>  		} else if (r->rid == RDT_RESOURCE_MBA) {
>  			hw_res->msr_base = MSR_IA32_MBA_BW_BASE;
>  			hw_res->msr_update = mba_wrmsr_amd;
> 
> 

Thank you for putting this together.

This change makes arch_has_empty_bitmaps redundant. Can it be removed?

Reinette
Re: [PATCH v3 01/10] x86/resctrl: Fix min_cbm_bits for AMD
Posted by Moger, Babu 3 years, 7 months ago 
On 8/23/22 15:56, Reinette Chatre wrote:
> Hi Babu,
>
> On 8/22/2022 6:42 AM, Babu Moger wrote:
>> AMD systems support zero CBM (capacity bit mask) for L3 allocation.
>> That is reflected in rdt_init_res_defs_amd() by:
>>
>> 	r->cache.arch_has_empty_bitmaps = true;
>>
>> However given the unified code in cbm_validate(), checking for:
>> 	val == 0 && !arch_has_empty_bitmaps
>>
>> is not enough because of another check in cbm_validate():
>>
>> 	if ((zero_bit - first_bit) < r->cache.min_cbm_bits)
>>
>> The default value of r->cache.min_cbm_bits = 1.
>>
>> Leading to:
>>
>> 	$ cd /sys/fs/resctrl
>> 	$ mkdir foo
>> 	$ cd foo
>> 	$ echo L3:0=0 > schemata
>>           -bash: echo: write error: Invalid argument
>> 	$ cat /sys/fs/resctrl/info/last_cmd_status
>> 	  Need at least 1 bits in the mask
>>
>> Fix the issue by initializing the min_cbm_bits to 0 for AMD. Also remove
>> the default setting of min_cbm_bits and initialize it separately.
>>
>> After the fix
>> 	$ cd /sys/fs/resctrl
>> 	$ mkdir foo
>> 	$ cd foo
>> 	$ echo L3:0=0 > schemata
>> 	$ cat /sys/fs/resctrl/info/last_cmd_status
>> 	  ok
>>
>> Link: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flkml%2F20220517001234.3137157-1-eranian%40google.com%2F&amp;data=05%7C01%7Cbabu.moger%40amd.com%7Cd695c39eb7d94d659db008da8549ed74%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637968849807214070%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=prSwl8bTHx0y3o9hBNxp3u%2FNu8SrNcEWUwDOCQCVURk%3D&amp;reserved=0
>> Fixes: 316e7f901f5a ("x86/resctrl: Add struct rdt_cache::arch_has_{sparse, empty}_bitmaps")
>> Signed-off-by: Stephane Eranian <eranian@google.com>
>> Signed-off-by: Babu Moger <babu.moger@amd.com>
>> Reviewed-by: Ingo Molnar <mingo@kernel.org>
>> ---
>>  arch/x86/kernel/cpu/resctrl/core.c |    8 ++------
>>  1 file changed, 2 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
>> index bb1c3f5f60c8..a5c51a14fbce 100644
>> --- a/arch/x86/kernel/cpu/resctrl/core.c
>> +++ b/arch/x86/kernel/cpu/resctrl/core.c
>> @@ -66,9 +66,6 @@ struct rdt_hw_resource rdt_resources_all[] = {
>>  			.rid			= RDT_RESOURCE_L3,
>>  			.name			= "L3",
>>  			.cache_level		= 3,
>> -			.cache = {
>> -				.min_cbm_bits	= 1,
>> -			},
>>  			.domains		= domain_init(RDT_RESOURCE_L3),
>>  			.parse_ctrlval		= parse_cbm,
>>  			.format_str		= "%d=%0*x",
>> @@ -83,9 +80,6 @@ struct rdt_hw_resource rdt_resources_all[] = {
>>  			.rid			= RDT_RESOURCE_L2,
>>  			.name			= "L2",
>>  			.cache_level		= 2,
>> -			.cache = {
>> -				.min_cbm_bits	= 1,
>> -			},
>>  			.domains		= domain_init(RDT_RESOURCE_L2),
>>  			.parse_ctrlval		= parse_cbm,
>>  			.format_str		= "%d=%0*x",
>> @@ -877,6 +871,7 @@ static __init void rdt_init_res_defs_intel(void)
>>  			r->cache.arch_has_sparse_bitmaps = false;
>>  			r->cache.arch_has_empty_bitmaps = false;
>>  			r->cache.arch_has_per_cpu_cfg = false;
>> +			r->cache.min_cbm_bits = 1;
>>  		} else if (r->rid == RDT_RESOURCE_MBA) {
>>  			hw_res->msr_base = MSR_IA32_MBA_THRTL_BASE;
>>  			hw_res->msr_update = mba_wrmsr_intel;
>> @@ -897,6 +892,7 @@ static __init void rdt_init_res_defs_amd(void)
>>  			r->cache.arch_has_sparse_bitmaps = true;
>>  			r->cache.arch_has_empty_bitmaps = true;
>>  			r->cache.arch_has_per_cpu_cfg = true;
>> +			r->cache.min_cbm_bits = 0;
>>  		} else if (r->rid == RDT_RESOURCE_MBA) {
>>  			hw_res->msr_base = MSR_IA32_MBA_BW_BASE;
>>  			hw_res->msr_update = mba_wrmsr_amd;
>>
>>
> Thank you for putting this together.
>
> This change makes arch_has_empty_bitmaps redundant. Can it be removed?

Hi Reinette,

Actually, I thought about that. Sure. We can remove it.

-- 
Thanks
Babu Moger

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