Re: [PATCH v6 11/16] x86/mtrr: construct a memory map with cache modes

Borislav Petkov
2023-05-09T12:10:16Z

On Tue, May 09, 2023 at 01:47:47PM +0200, Juergen Gross wrote:
> ... this call not being needed at all. We can reach this point only for
> mtrr_if != &generic_mtrr_ops.

Can't be too cautious with that MTRR maze but yeah, this is the MTRRs
disabled path. Ok, so even simpler then. I've renamed it to
generic_rebuild_map() to go along with the rest of the generic.c APIs.

Thx.

---
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index 163dca53796c..3a3b985006e2 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -458,8 +458,11 @@ static void map_add_var(void)
* removals of registers, which are complicated to handle without rebuild of
* the map.
*/
-static void rebuild_map(void)
+void generic_rebuild_map(void)
{
+ if (mtrr_if != &generic_mtrr_ops)
+ return;
+
cache_map_n = cache_map_fixed;

map_add_var();
@@ -1127,10 +1130,6 @@ static void generic_set_mtrr(unsigned int reg, unsigned long base,

cache_enable();
local_irq_restore(flags);
-
- /* On the first CPU rebuild the cache mode memory map. */
- if (smp_processor_id() == cpumask_first(cpu_online_mask))
- rebuild_map();
}

int generic_validate_add_page(unsigned long base, unsigned long size,
diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.c b/arch/x86/kernel/cpu/mtrr/mtrr.c
index 5fb61bb97ab1..bcde9a754f62 100644
--- a/arch/x86/kernel/cpu/mtrr/mtrr.c
+++ b/arch/x86/kernel/cpu/mtrr/mtrr.c
@@ -187,6 +187,8 @@ static void set_mtrr(unsigned int reg, unsigned long base, unsigned long size,
};

stop_machine_cpuslocked(mtrr_rendezvous_handler, &data, cpu_online_mask);
+
+ generic_rebuild_map();
}

/**
diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.h b/arch/x86/kernel/cpu/mtrr/mtrr.h
index 48ffd89cf3a6..81babff29c59 100644
--- a/arch/x86/kernel/cpu/mtrr/mtrr.h
+++ b/arch/x86/kernel/cpu/mtrr/mtrr.h
@@ -79,3 +79,4 @@ extern const struct mtrr_ops centaur_mtrr_ops;

extern int changed_by_mtrr_cleanup;
extern int mtrr_cleanup(void);
+void generic_rebuild_map(void);

--
Regards/Gruss,
Boris.