This is a note to let you know that I've just added the patch titled
x86/resctrl: Fix to restore to original value when re-enabling hardware prefetch register
to the 5.10-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-fix-to-restore-to-original-value-when-re.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 7d09c4196f8eeea8bb45ab1c7c1b602d662b2c53
Author: Kohei Tarumizu <tarumizu.kohei@xxxxxxxxxxx>
Date: Wed Aug 24 09:44:10 2022 -0700
x86/resctrl: Fix to restore to original value when re-enabling hardware prefetch register
[ Upstream commit 499c8bb4693d1c8d8f3d6dd38e5bdde3ff5bd906 ]
The current pseudo_lock.c code overwrites the value of the
MSR_MISC_FEATURE_CONTROL to 0 even if the original value is not 0.
Therefore, modify it to save and restore the original values.
Fixes: 018961ae5579 ("x86/intel_rdt: Pseudo-lock region creation/removal core")
Fixes: 443810fe6160 ("x86/intel_rdt: Create debugfs files for pseudo-locking testing")
Fixes: 8a2fc0e1bc0c ("x86/intel_rdt: More precise L2 hit/miss measurements")
Signed-off-by: Kohei Tarumizu <tarumizu.kohei@xxxxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Acked-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Link: https://lkml.kernel.org/r/eb660f3c2010b79a792c573c02d01e8e841206ad.1661358182.git.reinette.chatre@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
index 0daf2f1cf7a8..465dce141bfc 100644
--- a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
+++ b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
@@ -416,6 +416,7 @@ static int pseudo_lock_fn(void *_rdtgrp)
struct pseudo_lock_region *plr = rdtgrp->plr;
u32 rmid_p, closid_p;
unsigned long i;
+ u64 saved_msr;
#ifdef CONFIG_KASAN
/*
* The registers used for local register variables are also used
@@ -459,6 +460,7 @@ static int pseudo_lock_fn(void *_rdtgrp)
* the buffer and evict pseudo-locked memory read earlier from the
* cache.
*/
+ saved_msr = __rdmsr(MSR_MISC_FEATURE_CONTROL);
__wrmsr(MSR_MISC_FEATURE_CONTROL, prefetch_disable_bits, 0x0);
closid_p = this_cpu_read(pqr_state.cur_closid);
rmid_p = this_cpu_read(pqr_state.cur_rmid);
@@ -510,7 +512,7 @@ static int pseudo_lock_fn(void *_rdtgrp)
__wrmsr(IA32_PQR_ASSOC, rmid_p, closid_p);
/* Re-enable the hardware prefetcher(s) */
- wrmsr(MSR_MISC_FEATURE_CONTROL, 0x0, 0x0);
+ wrmsrl(MSR_MISC_FEATURE_CONTROL, saved_msr);
local_irq_enable();
plr->thread_done = 1;
@@ -867,6 +869,7 @@ bool rdtgroup_pseudo_locked_in_hierarchy(struct rdt_domain *d)
static int measure_cycles_lat_fn(void *_plr)
{
struct pseudo_lock_region *plr = _plr;
+ u32 saved_low, saved_high;
unsigned long i;
u64 start, end;
void *mem_r;
@@ -875,6 +878,7 @@ static int measure_cycles_lat_fn(void *_plr)
/*
* Disable hardware prefetchers.
*/
+ rdmsr(MSR_MISC_FEATURE_CONTROL, saved_low, saved_high);
wrmsr(MSR_MISC_FEATURE_CONTROL, prefetch_disable_bits, 0x0);
mem_r = READ_ONCE(plr->kmem);
/*
@@ -891,7 +895,7 @@ static int measure_cycles_lat_fn(void *_plr)
end = rdtsc_ordered();
trace_pseudo_lock_mem_latency((u32)(end - start));
}
- wrmsr(MSR_MISC_FEATURE_CONTROL, 0x0, 0x0);
+ wrmsr(MSR_MISC_FEATURE_CONTROL, saved_low, saved_high);
local_irq_enable();
plr->thread_done = 1;
wake_up_interruptible(&plr->lock_thread_wq);
@@ -936,6 +940,7 @@ static int measure_residency_fn(struct perf_event_attr *miss_attr,
u64 hits_before = 0, hits_after = 0, miss_before = 0, miss_after = 0;
struct perf_event *miss_event, *hit_event;
int hit_pmcnum, miss_pmcnum;
+ u32 saved_low, saved_high;
unsigned int line_size;
unsigned int size;
unsigned long i;
@@ -969,6 +974,7 @@ static int measure_residency_fn(struct perf_event_attr *miss_attr,
/*
* Disable hardware prefetchers.
*/
+ rdmsr(MSR_MISC_FEATURE_CONTROL, saved_low, saved_high);
wrmsr(MSR_MISC_FEATURE_CONTROL, prefetch_disable_bits, 0x0);
/* Initialize rest of local variables */
@@ -1027,7 +1033,7 @@ static int measure_residency_fn(struct perf_event_attr *miss_attr,
*/
rmb();
/* Re-enable hardware prefetchers */
- wrmsr(MSR_MISC_FEATURE_CONTROL, 0x0, 0x0);
+ wrmsr(MSR_MISC_FEATURE_CONTROL, saved_low, saved_high);
local_irq_enable();
out_hit:
perf_event_release_kernel(hit_event);
