This is a note to let you know that I've just added the patch titled
x86/resctrl: Remove hard-coded memory bandwidth limit
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-resctrl-remove-hard-coded-memory-bandwidth-limit.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 487333a710a06455d76b3083f60869c17bc721cb
Author: Babu Moger <babu.moger@xxxxxxx>
Date: Mon Jan 15 16:52:27 2024 -0600
x86/resctrl: Remove hard-coded memory bandwidth limit
[ Upstream commit 0976783bb123f30981bc1e7a14d9626a6f63aeac ]
The QOS Memory Bandwidth Enforcement Limit is reported by
CPUID_Fn80000020_EAX_x01 and CPUID_Fn80000020_EAX_x02:
Bits Description
31:0 BW_LEN: Size of the QOS Memory Bandwidth Enforcement Limit.
Newer processors can support higher bandwidth limit than the current
hard-coded value. Remove latter and detect using CPUID instead. Also,
update the register variables eax and edx to match the AMD CPUID
definition.
The CPUID details are documented in the Processor Programming Reference
(PPR) Vol 1.1 for AMD Family 19h Model 11h B1 - 55901 Rev 0.25 in the
Link tag below.
Fixes: 4d05bf71f157 ("x86/resctrl: Introduce AMD QOS feature")
Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537
Link: https://lore.kernel.org/r/c26a8ca79d399ed076cf8bf2e9fbc58048808289.1705359148.git.babu.moger@xxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 19e0681f04356..d04371e851b4c 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -231,9 +231,7 @@ static bool __get_mem_config_intel(struct rdt_resource *r)
static bool __rdt_get_mem_config_amd(struct rdt_resource *r)
{
struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
- union cpuid_0x10_3_eax eax;
- union cpuid_0x10_x_edx edx;
- u32 ebx, ecx, subleaf;
+ u32 eax, ebx, ecx, edx, subleaf;
/*
* Query CPUID_Fn80000020_EDX_x01 for MBA and
@@ -241,9 +239,9 @@ static bool __rdt_get_mem_config_amd(struct rdt_resource *r)
*/
subleaf = (r->rid == RDT_RESOURCE_SMBA) ? 2 : 1;
- cpuid_count(0x80000020, subleaf, &eax.full, &ebx, &ecx, &edx.full);
- hw_res->num_closid = edx.split.cos_max + 1;
- r->default_ctrl = MAX_MBA_BW_AMD;
+ cpuid_count(0x80000020, subleaf, &eax, &ebx, &ecx, &edx);
+ hw_res->num_closid = edx + 1;
+ r->default_ctrl = 1 << eax;
/* AMD does not use delay */
r->membw.delay_linear = false;
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index a4f1aa15f0a2a..d2979748fae47 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -18,7 +18,6 @@
#define MBM_OVERFLOW_INTERVAL 1000
#define MAX_MBA_BW 100u
#define MBA_IS_LINEAR 0x4
-#define MAX_MBA_BW_AMD 0x800
#define MBM_CNTR_WIDTH_OFFSET_AMD 20
#define RMID_VAL_ERROR BIT_ULL(63)
