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x86/resctrl: Add struct rdt_membw::arch_needs_linear to explain AMD/Intel MBA difference

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The configuration values user-space provides to the resctrl filesystem
are ABI. To make this work on another architecture, all the ABI bits
should be moved out of /arch/x86 and under /fs.

To do this, the differences between AMD and Intel CPUs needs to be
explained to resctrl via resource properties, instead of function
pointers that let the arch code accept subtly different values on
different platforms/architectures.

For MBA, Intel CPUs reject configuration attempts for non-linear
resources, whereas AMD ignore this field as its MBA resource is never
linear. To merge the parse/validate functions, this difference needs to
be explained.

Add struct rdt_membw::arch_needs_linear to indicate the arch code needs
the linear property to be true to configure this resource. AMD can set
this and delay_linear to false. Intel can set arch_needs_linear to
true to keep the existing "No support for non-linear MB domains" error
message for affected platforms.

 [ bp: convert "we" etc to passive voice. ]

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Link: https://lkml.kernel.org/r/20200708163929.2783-8-james.morse@arm.com
This commit is contained in:
James Morse
2020-07-08 16:39:26 +00:00
committed by Borislav Petkov
parent e6b2fac36f
commit 41215b7947
3 changed files with 12 additions and 1 deletions
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8
arch/x86/kernel/cpu/resctrl/ctrlmondata.c
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@@ -33,6 +33,12 @@ static bool bw_validate_amd(char *buf, unsigned long *data,
unsigned long bw;
int ret;
/* temporary: always false on AMD */
if (!r->membw.delay_linear && r->membw.arch_needs_linear) {
rdt_last_cmd_puts("No support for non-linear MB domains\n");
return false;
}
ret = kstrtoul(buf, 10, &bw);
if (ret) {
rdt_last_cmd_printf("Non-decimal digit in MB value %s\n", buf);
@@ -82,7 +88,7 @@ static bool bw_validate(char *buf, unsigned long *data, struct rdt_resource *r)
/*
* Only linear delay values is supported for current Intel SKUs.
*/
if (!r->membw.delay_linear) {
if (!r->membw.delay_linear && r->membw.arch_needs_linear) {
rdt_last_cmd_puts("No support for non-linear MB domains\n");
return false;
}