[PATCH v2 05/10] x86/mtrr: split generic_set_all()

From: Juergen Gross
Date: Sat Aug 20 2022 - 05:26:12 EST


Split generic_set_all() into multiple parts, while moving the main
function body into cacheinfo.c.

This prepares the support of PAT without needing MTRR support by
moving the main function body of generic_set_all() into cacheinfo.c
while renaming it to cache_cpu_init(). The MTRR specific parts are
moved into a dedicated small function called by cache_cpu_init().
The PAT and MTRR specific functions are called conditionally based
on the cache_generic bit settings.

The setting of smp_changes_mask is merged into the (new) function
mtrr_generic_set_state() used to call set_mtrr_state(). It was
probably split in ancient times, as atomic operations while running
uncached might be quite expensive, but OTOH only systems with a
broken BIOS should ever require to set any bit in smp_changes_mask,
so just hurting those devices with a penalty of a few microseconds
during boot shouldn't be a real issue.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V2:
- new patch
---
arch/x86/include/asm/cacheinfo.h | 1 +
arch/x86/include/asm/mtrr.h | 2 ++
arch/x86/kernel/cpu/cacheinfo.c | 19 +++++++++++++++++++
arch/x86/kernel/cpu/mtrr/generic.c | 15 ++-------------
4 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/cacheinfo.h b/arch/x86/include/asm/cacheinfo.h
index 313a6920d0f9..563d9cb5fcf5 100644
--- a/arch/x86/include/asm/cacheinfo.h
+++ b/arch/x86/include/asm/cacheinfo.h
@@ -12,5 +12,6 @@ void cacheinfo_hygon_init_llc_id(struct cpuinfo_x86 *c, int cpu);

void cache_disable(void);
void cache_enable(void);
+void cache_cpu_init(void);

#endif /* _ASM_X86_CACHEINFO_H */
diff --git a/arch/x86/include/asm/mtrr.h b/arch/x86/include/asm/mtrr.h
index 12a16caed395..986249a2b9b6 100644
--- a/arch/x86/include/asm/mtrr.h
+++ b/arch/x86/include/asm/mtrr.h
@@ -50,6 +50,7 @@ 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);
# else
static inline u8 mtrr_type_lookup(u64 addr, u64 end, u8 *uniform)
{
@@ -91,6 +92,7 @@ static inline void mtrr_centaur_report_mcr(int mcr, u32 lo, u32 hi)
#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)
# endif

#ifdef CONFIG_COMPAT
diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c
index 47e2c72fa8a4..36378604ec61 100644
--- a/arch/x86/kernel/cpu/cacheinfo.c
+++ b/arch/x86/kernel/cpu/cacheinfo.c
@@ -1120,3 +1120,22 @@ void cache_enable(void) __releases(cache_disable_lock)

raw_spin_unlock(&cache_disable_lock);
}
+
+void cache_cpu_init(void)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ cache_disable();
+
+ /* Set MTRR state. */
+ if (cache_generic & CACHE_GENERIC_MTRR)
+ mtrr_generic_set_state();
+
+ /* Set PAT. */
+ if (cache_generic & CACHE_GENERIC_PAT)
+ pat_init();
+
+ cache_enable();
+ local_irq_restore(flags);
+}
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index a9ac159b1566..0be6d43ec1fe 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -736,30 +736,19 @@ void mtrr_enable(void)
mtrr_wrmsr(MSR_MTRRdefType, *lo, *hi);
}

-static void generic_set_all(void)
+void mtrr_generic_set_state(void)
{
unsigned long mask, count;
- unsigned long flags;
-
- local_irq_save(flags);
- cache_disable();

/* Actually set the state */
mask = set_mtrr_state();

- /* also set PAT */
- pat_init();
-
- cache_enable();
- local_irq_restore(flags);
-
/* Use the atomic bitops to update the global mask */
for (count = 0; count < sizeof(mask) * 8; ++count) {
if (mask & 0x01)
set_bit(count, &smp_changes_mask);
mask >>= 1;
}
-
}

/**
@@ -859,7 +848,7 @@ int positive_have_wrcomb(void)
* Generic structure...
*/
const struct mtrr_ops generic_mtrr_ops = {
- .set_all = generic_set_all,
+ .set_all = cache_cpu_init,
.get = generic_get_mtrr,
.get_free_region = generic_get_free_region,
.set = generic_set_mtrr,
--
2.35.3