[5.15,158/530] x86/resctrl: Fix to restore to original value when re-enabling hardware prefetch register
Commit Message
Greg KH
Oct. 24, 2022, 11:28 a.m. UTC
From: Kohei Tarumizu <tarumizu.kohei@fujitsu.com> [ 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@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 Signed-off-by: Sasha Levin <sashal@kernel.org> --- arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c index db813f819ad6..4d8398986f78 100644 --- a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c +++ b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c @@ -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);