Looks good. > -----Original Message----- > From: James Morse <[email protected]> > Sent: Monday, May 18, 2020 8:19 AM > To: [email protected]; [email protected] > Cc: Fenghua Yu <[email protected]>; Reinette Chatre > <[email protected]>; Thomas Gleixner <[email protected]>; Ingo > Molnar <[email protected]>; Borislav Petkov <[email protected]>; H Peter Anvin > <[email protected]>; Moger, Babu <[email protected]>; James Morse > <[email protected]> > Subject: [PATCH v3 07/10] x86/resctrl: Add arch_needs_linear to explain > AMD/Intel MBA difference > > The configuration values user-space provides to the resctrl filesystem > are ABI. To make this work on another architecture we want to move all > the ABI bits 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 we need to explain > this difference. > > Add 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. > > CC: Babu Moger <[email protected]> > Signed-off-by: James Morse <[email protected]> > Reviewed-by: Reinette Chatre <[email protected]>
Reviewed-by: Babu Moger <[email protected]> > > --- > An alternative to this is for Intel non-linear MBA resources to > clear alloc_capable as they can't be configured anyway. > --- > arch/x86/kernel/cpu/resctrl/core.c | 3 +++ > arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 8 +++++++- > arch/x86/kernel/cpu/resctrl/internal.h | 2 ++ > 3 files changed, 12 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/cpu/resctrl/core.c > b/arch/x86/kernel/cpu/resctrl/core.c > index e1fed3928b59..c6b73b0ee070 100644 > --- a/arch/x86/kernel/cpu/resctrl/core.c > +++ b/arch/x86/kernel/cpu/resctrl/core.c > @@ -260,6 +260,7 @@ static bool __get_mem_config_intel(struct rdt_resource > *r) > r->num_closid = edx.split.cos_max + 1; > max_delay = eax.split.max_delay + 1; > r->default_ctrl = MAX_MBA_BW; > + r->membw.arch_needs_linear = true; > if (ecx & MBA_IS_LINEAR) { > r->membw.delay_linear = true; > r->membw.min_bw = MAX_MBA_BW - max_delay; > @@ -267,6 +268,7 @@ static bool __get_mem_config_intel(struct rdt_resource > *r) > } else { > if (!rdt_get_mb_table(r)) > return false; > + r->membw.arch_needs_linear = false; > } > r->data_width = 3; > > @@ -288,6 +290,7 @@ static bool __rdt_get_mem_config_amd(struct > rdt_resource *r) > > /* AMD does not use delay */ > r->membw.delay_linear = false; > + r->membw.arch_needs_linear = false; > > r->membw.min_bw = 0; > r->membw.bw_gran = 1; > diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c > b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c > index 934c8fb8a64a..e3bcd77add2b 100644 > --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c > +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c > @@ -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; > } > diff --git a/arch/x86/kernel/cpu/resctrl/internal.h > b/arch/x86/kernel/cpu/resctrl/internal.h > index dd51e23e346b..0b288b6fefd9 100644 > --- a/arch/x86/kernel/cpu/resctrl/internal.h > +++ b/arch/x86/kernel/cpu/resctrl/internal.h > @@ -370,6 +370,7 @@ struct rdt_cache { > * struct rdt_membw - Memory bandwidth allocation related data > * @min_bw: Minimum memory bandwidth percentage user can > request > * @bw_gran: Granularity at which the memory bandwidth is allocated > + * @arch_needs_linear: True if we can't configure non-linear resources > * @delay_linear: True if memory B/W delay is in linear scale > * @mba_sc: True if MBA software controller(mba_sc) is enabled > * @mb_map: Mapping of memory B/W percentage to memory B/W > delay > @@ -378,6 +379,7 @@ struct rdt_membw { > u32 min_bw; > u32 bw_gran; > u32 delay_linear; > + bool arch_needs_linear; > bool mba_sc; > u32 *mb_map; > }; > -- > 2.19.1
