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Date: Wed, 2 Nov 2022 08:47:12 +0100
From: Juergen Gross <jgross@...e.com>
To: linux-kernel@...r.kernel.org, x86@...nel.org
Cc: Juergen Gross <jgross@...e.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH v5 15/16] x86: do MTRR/PAT setup on all secondary CPUs in parallel
Instead of serializing MTRR/PAT setup on the secondary CPUs in order
to avoid clobbering of static variables used by the setup process, put
those variables into a structure held on the stack and drop the
serialization.
This speeds up the start of secondary CPUs a little bit (on a small
system with 8 CPUs the time needed for starting the secondary CPUs was
measured to go down from about 60 milliseconds without this patch to
about 55 milliseconds with this patch applied).
Signed-off-by: Juergen Gross <jgross@...e.com>
---
V4:
- new patch
---
arch/x86/include/asm/cacheinfo.h | 10 ++++++--
arch/x86/include/asm/mtrr.h | 13 +++++-----
arch/x86/kernel/cpu/cacheinfo.c | 28 ++++++++-------------
arch/x86/kernel/cpu/mtrr/generic.c | 40 ++++++++++++++----------------
4 files changed, 45 insertions(+), 46 deletions(-)
diff --git a/arch/x86/include/asm/cacheinfo.h b/arch/x86/include/asm/cacheinfo.h
index ce9685fc78d8..f66578e1e4e1 100644
--- a/arch/x86/include/asm/cacheinfo.h
+++ b/arch/x86/include/asm/cacheinfo.h
@@ -10,8 +10,14 @@ extern unsigned int memory_caching_control;
void cacheinfo_amd_init_llc_id(struct cpuinfo_x86 *c, int cpu);
void cacheinfo_hygon_init_llc_id(struct cpuinfo_x86 *c, int cpu);
-void cache_disable(void);
-void cache_enable(void);
+struct cache_state {
+ unsigned long cr4;
+ u32 mtrr_deftype_lo;
+ u32 mtrr_deftype_hi;
+};
+
+void cache_disable(struct cache_state *state);
+void cache_enable(struct cache_state *state);
void set_cache_aps_delayed_init(bool val);
bool get_cache_aps_delayed_init(void);
void cache_bp_init(void);
diff --git a/arch/x86/include/asm/mtrr.h b/arch/x86/include/asm/mtrr.h
index f0eeaf6e5f5f..2ea4a9de7318 100644
--- a/arch/x86/include/asm/mtrr.h
+++ b/arch/x86/include/asm/mtrr.h
@@ -23,6 +23,7 @@
#ifndef _ASM_X86_MTRR_H
#define _ASM_X86_MTRR_H
+#include <asm/cacheinfo.h>
#include <uapi/asm/mtrr.h>
/*
@@ -44,9 +45,9 @@ extern void mtrr_centaur_report_mcr(int mcr, u32 lo, u32 hi);
extern void mtrr_bp_restore(void);
extern int mtrr_trim_uncached_memory(unsigned long end_pfn);
extern int amd_special_default_mtrr(void);
-void mtrr_disable(void);
-void mtrr_enable(void);
-void mtrr_generic_set_state(void);
+void mtrr_disable(struct cache_state *state);
+void mtrr_enable(struct cache_state *state);
+void mtrr_generic_set_state(struct cache_state *state);
# else
static inline u8 mtrr_type_lookup(u64 addr, u64 end, u8 *uniform)
{
@@ -84,9 +85,9 @@ static inline void mtrr_centaur_report_mcr(int mcr, u32 lo, u32 hi)
}
#define mtrr_bp_init() do {} while (0)
#define mtrr_bp_restore() do {} while (0)
-#define mtrr_disable() do {} while (0)
-#define mtrr_enable() do {} while (0)
-#define mtrr_generic_set_state() do {} while (0)
+#define mtrr_disable(s) do {} while (0)
+#define mtrr_enable(s) do {} while (0)
+#define mtrr_generic_set_state(s) do {} while (0)
# endif
#ifdef CONFIG_COMPAT
diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c
index 231cf1ff0641..7e370c979417 100644
--- a/arch/x86/kernel/cpu/cacheinfo.c
+++ b/arch/x86/kernel/cpu/cacheinfo.c
@@ -1057,10 +1057,7 @@ int populate_cache_leaves(unsigned int cpu)
* The caller must ensure that local interrupts are disabled and
* are reenabled after cache_enable() has been called.
*/
-static unsigned long saved_cr4;
-static DEFINE_RAW_SPINLOCK(cache_disable_lock);
-
-void cache_disable(void) __acquires(cache_disable_lock)
+void cache_disable(struct cache_state *state)
{
unsigned long cr0;
@@ -1071,8 +1068,6 @@ void cache_disable(void) __acquires(cache_disable_lock)
* changes to the way the kernel boots
*/
- raw_spin_lock(&cache_disable_lock);
-
/* Enter the no-fill (CD=1, NW=0) cache mode and flush caches. */
cr0 = read_cr0() | X86_CR0_CD;
write_cr0(cr0);
@@ -1088,8 +1083,8 @@ void cache_disable(void) __acquires(cache_disable_lock)
/* Save value of CR4 and clear Page Global Enable (bit 7) */
if (cpu_feature_enabled(X86_FEATURE_PGE)) {
- saved_cr4 = __read_cr4();
- __write_cr4(saved_cr4 & ~X86_CR4_PGE);
+ state->cr4 = __read_cr4();
+ __write_cr4(state->cr4 & ~X86_CR4_PGE);
}
/* Flush all TLBs via a mov %cr3, %reg; mov %reg, %cr3 */
@@ -1097,46 +1092,45 @@ void cache_disable(void) __acquires(cache_disable_lock)
flush_tlb_local();
if (cpu_feature_enabled(X86_FEATURE_MTRR))
- mtrr_disable();
+ mtrr_disable(state);
/* Again, only flush caches if we have to. */
if (!static_cpu_has(X86_FEATURE_SELFSNOOP))
wbinvd();
}
-void cache_enable(void) __releases(cache_disable_lock)
+void cache_enable(struct cache_state *state)
{
/* Flush TLBs (no need to flush caches - they are disabled) */
count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
flush_tlb_local();
if (cpu_feature_enabled(X86_FEATURE_MTRR))
- mtrr_enable();
+ mtrr_enable(state);
/* Enable caches */
write_cr0(read_cr0() & ~X86_CR0_CD);
/* Restore value of CR4 */
if (cpu_feature_enabled(X86_FEATURE_PGE))
- __write_cr4(saved_cr4);
-
- raw_spin_unlock(&cache_disable_lock);
+ __write_cr4(state->cr4);
}
static void cache_cpu_init(void)
{
unsigned long flags;
+ struct cache_state state;
local_irq_save(flags);
- cache_disable();
+ cache_disable(&state);
if (memory_caching_control & CACHE_MTRR)
- mtrr_generic_set_state();
+ mtrr_generic_set_state(&state);
if (memory_caching_control & CACHE_PAT)
pat_cpu_init();
- cache_enable();
+ cache_enable(&state);
local_irq_restore(flags);
}
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index 2f2485d6657f..cddb440f330d 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -663,18 +663,13 @@ static bool set_mtrr_var_ranges(unsigned int index, struct mtrr_var_range *vr)
return changed;
}
-static u32 deftype_lo, deftype_hi;
-
/**
* set_mtrr_state - Set the MTRR state for this CPU.
*
- * NOTE: The CPU must already be in a safe state for MTRR changes, including
- * measures that only a single CPU can be active in set_mtrr_state() in
- * order to not be subject to races for usage of deftype_lo (this is
- * accomplished by taking cache_disable_lock).
+ * NOTE: The CPU must already be in a safe state for MTRR changes.
* RETURNS: 0 if no changes made, else a mask indicating what was changed.
*/
-static unsigned long set_mtrr_state(void)
+static unsigned long set_mtrr_state(struct cache_state *state)
{
unsigned long change_mask = 0;
unsigned int i;
@@ -691,38 +686,40 @@ static unsigned long set_mtrr_state(void)
* Set_mtrr_restore restores the old value of MTRRdefType,
* so to set it we fiddle with the saved value:
*/
- if ((deftype_lo & 0xff) != mtrr_state.def_type
- || ((deftype_lo & 0xc00) >> 10) != mtrr_state.enabled) {
-
- deftype_lo = (deftype_lo & ~0xcff) | mtrr_state.def_type |
- (mtrr_state.enabled << 10);
+ if ((state->mtrr_deftype_lo & 0xff) != mtrr_state.def_type
+ || ((state->mtrr_deftype_lo & 0xc00) >> 10) != mtrr_state.enabled) {
+ state->mtrr_deftype_lo = (state->mtrr_deftype_lo & ~0xcff) |
+ mtrr_state.def_type |
+ (mtrr_state.enabled << 10);
change_mask |= MTRR_CHANGE_MASK_DEFTYPE;
}
return change_mask;
}
-void mtrr_disable(void)
+void mtrr_disable(struct cache_state *state)
{
/* Save MTRR state */
- rdmsr(MSR_MTRRdefType, deftype_lo, deftype_hi);
+ rdmsr(MSR_MTRRdefType, state->mtrr_deftype_lo, state->mtrr_deftype_hi);
/* Disable MTRRs, and set the default type to uncached */
- mtrr_wrmsr(MSR_MTRRdefType, deftype_lo & ~0xcff, deftype_hi);
+ mtrr_wrmsr(MSR_MTRRdefType, state->mtrr_deftype_lo & ~0xcff,
+ state->mtrr_deftype_hi);
}
-void mtrr_enable(void)
+void mtrr_enable(struct cache_state *state)
{
/* Intel (P6) standard MTRRs */
- mtrr_wrmsr(MSR_MTRRdefType, deftype_lo, deftype_hi);
+ mtrr_wrmsr(MSR_MTRRdefType, state->mtrr_deftype_lo,
+ state->mtrr_deftype_hi);
}
-void mtrr_generic_set_state(void)
+void mtrr_generic_set_state(struct cache_state *state)
{
unsigned long mask, count;
/* Actually set the state */
- mask = set_mtrr_state();
+ mask = set_mtrr_state(state);
/* Use the atomic bitops to update the global mask */
for (count = 0; count < sizeof(mask) * 8; ++count) {
@@ -747,11 +744,12 @@ static void generic_set_mtrr(unsigned int reg, unsigned long base,
{
unsigned long flags;
struct mtrr_var_range *vr;
+ struct cache_state state;
vr = &mtrr_state.var_ranges[reg];
local_irq_save(flags);
- cache_disable();
+ cache_disable(&state);
if (size == 0) {
/*
@@ -770,7 +768,7 @@ static void generic_set_mtrr(unsigned int reg, unsigned long base,
mtrr_wrmsr(MTRRphysMask_MSR(reg), vr->mask_lo, vr->mask_hi);
}
- cache_enable();
+ cache_enable(&state);
local_irq_restore(flags);
}
--
2.35.3
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