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Subject[PATCH v5 07/21] x86/resctrl: Abstract and use supports_mba_mbps()
Date
To determine whether the mba_MBps option to resctrl should be supported,
resctrl tests the boot CPUs' x86_vendor.

This isn't portable, and needs abstracting behind a helper so this check
can be part of the filesystem code that moves to /fs/.

Re-use the tests set_mba_sc() does to determine if the mba_sc is supported
on this system. An 'alloc_capable' test is added so that support for the
controls isn't implied by the 'delay_linear' property, which is always
true for MPAM.

Reviewed-by: Jamie Iles <quic_jiles@quicinc.com>
Tested-by: Xin Hao <xhao@linux.alibaba.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
---
Changes since v3:
* Added use in resctrle_online_domain()

Changes since v1:
* Capitalisation
* Added MPAM example in commit message
* Fixed supports_mba_mbps() logic error in rdt_parse_param()
---
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index b32ceff8325a..49d9e2c3c743 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1890,17 +1890,26 @@ void rdt_domain_reconfigure_cdp(struct rdt_resource *r)
}

/*
- * Enable or disable the MBA software controller
- * which helps user specify bandwidth in MBps.
* MBA software controller is supported only if
* MBM is supported and MBA is in linear scale.
*/
+static bool supports_mba_mbps(void)
+{
+ struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
+
+ return (is_mbm_enabled() &&
+ r->alloc_capable && is_mba_linear());
+}
+
+/*
+ * Enable or disable the MBA software controller
+ * which helps user specify bandwidth in MBps.
+ */
static int set_mba_sc(bool mba_sc)
{
struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;

- if (!is_mbm_enabled() || !is_mba_linear() ||
- mba_sc == is_mba_sc(r))
+ if (!supports_mba_mbps() || mba_sc == is_mba_sc(r))
return -EINVAL;

r->membw.mba_sc = mba_sc;
@@ -2255,7 +2264,7 @@ static int rdt_parse_param(struct fs_context *fc, struct fs_parameter *param)
ctx->enable_cdpl2 = true;
return 0;
case Opt_mba_mbps:
- if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
+ if (!supports_mba_mbps())
return -EINVAL;
ctx->enable_mba_mbps = true;
return 0;
--
2.30.2
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