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x86/resctrl: Fix to restore to original value when re-enabling hardware prefetch register

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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: 018961ae55 ("x86/intel_rdt: Pseudo-lock region creation/removal core")
Fixes: 443810fe61 ("x86/intel_rdt: Create debugfs files for pseudo-locking testing")
Fixes: 8a2fc0e1bc ("x86/intel_rdt: More precise L2 hit/miss measurements")
Signed-off-by: Kohei Tarumizu <tarumizu.kohei@fujitsu.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/eb660f3c2010b79a792c573c02d01e8e841206ad.1661358182.git.reinette.chatre@intel.com
This commit is contained in:
Kohei Tarumizu 2022-08-24 09:44:10 -07:00 committed by Dave Hansen
parent b90cb10531
commit 499c8bb469
1 changed files with 9 additions and 3 deletions
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12
arch/x86/kernel/cpu/resctrl/pseudo_lock.c
View file

@ -420,6 +420,7 @@ 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
@ -463,6 +464,7 @@ 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);
@ -514,7 +516,7 @@ 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;
@ -871,6 +873,7 @@ 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;
@ -879,6 +882,7 @@ 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);
/*
@ -895,7 +899,7 @@ 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);
@ -940,6 +944,7 @@ 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;
@ -973,6 +978,7 @@ 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 */
@ -1031,7 +1037,7 @@ 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);