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x86/resctrl: Block use of mba_MBps mount option on Sub-NUMA Cluster (SNC) systems

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When SNC is enabled there is a mismatch between the MBA control function
which operates at L3 cache scope and the MBM monitor functions which
measure memory bandwidth on each SNC node.

Block use of the mba_MBps when scopes for MBA/MBM do not match.

Improve user diagnostics by adding invalfc() message when mba_MBps
is not supported.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20240628215619.76401-8-tony.luck@intel.com
This commit is contained in:
Tony Luck
2024-06-28 14:56:07 -07:00
committed by Borislav Petkov (AMD)
parent e13db55b5a
commit ac20aa4230
1 changed files with 9 additions and 3 deletions
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arch/x86/kernel/cpu/resctrl/rdtgroup.c
+9 -3
View File
@@ -2335,14 +2335,18 @@ static void mba_sc_domain_destroy(struct rdt_resource *r,
/*
* MBA software controller is supported only if
* MBM is supported and MBA is in linear scale.
* MBM is supported and MBA is in linear scale,
* and the MBM monitor scope is the same as MBA
* control scope.
*/
static bool supports_mba_mbps(void)
{
struct rdt_resource *rmbm = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
return (is_mbm_local_enabled() &&
r->alloc_capable && is_mba_linear());
r->alloc_capable && is_mba_linear() &&
r->ctrl_scope == rmbm->mon_scope);
}
/*
@@ -2750,6 +2754,7 @@ static int rdt_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
struct rdt_fs_context *ctx = rdt_fc2context(fc);
struct fs_parse_result result;
const char *msg;
int opt;
opt = fs_parse(fc, rdt_fs_parameters, param, &result);
@@ -2764,8 +2769,9 @@ static int rdt_parse_param(struct fs_context *fc, struct fs_parameter *param)
ctx->enable_cdpl2 = true;
return 0;
case Opt_mba_mbps:
msg = "mba_MBps requires local MBM and linear scale MBA at L3 scope";
if (!supports_mba_mbps())
return -EINVAL;
return invalfc(fc, msg);
ctx->enable_mba_mbps = true;
return 0;
case Opt_debug: