The following commit has been merged into the x86/cache branch of tip:
Commit-ID: ac20aa423052553c005089b00f1e3caf79d3c1d3
Gitweb: https://git.kernel.org/tip/ac20aa423052553c005089b00f1e3caf79d3c1d3
Author: Tony Luck <tony.luck@xxxxxxxxx>
AuthorDate: Fri, 28 Jun 2024 14:56:07 -07:00
Committer: Borislav Petkov (AMD) <bp@xxxxxxxxx>
CommitterDate: Tue, 02 Jul 2024 19:49:54 +02:00
x86/resctrl: Block use of mba_MBps mount option on Sub-NUMA Cluster (SNC) systems
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@xxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Tested-by: Babu Moger <babu.moger@xxxxxxx>
Link: https://lore.kernel.org/r/20240628215619.76401-8-tony.luck@xxxxxxxxx
---
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index eb3bbfa..d3b0fa9 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -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:
|