[PATCH v6 09/16] x86/mtrr: allocate mtrr_value array dynamically

Juergen Gross
2023-05-02T12:11:19Z

The mtrr_value[] array is a static variable, which is used only in a
few configurations. Consuming 6kB is ridiculous for this case,
especially as the array doesn't need to be that large and it can easily
be allocated dynamically.

Signed-off-by: Juergen Gross <jgross@suse.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
---
V5:
- check for allocation failure (Kai Huang, Boris Petkov)
- add #ifdef
V6:
- rebase
---
arch/x86/kernel/cpu/mtrr/legacy.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mtrr/legacy.c b/arch/x86/kernel/cpu/mtrr/legacy.c
index 7d379fb26cce..d25882fcf181 100644
--- a/arch/x86/kernel/cpu/mtrr/legacy.c
+++ b/arch/x86/kernel/cpu/mtrr/legacy.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0-only

#include <linux/types.h>
+#include <linux/slab.h>
#include <linux/syscore_ops.h>
#include <asm/cpufeature.h>
#include <asm/mtrr.h>
@@ -38,12 +39,15 @@ struct mtrr_value {
unsigned long lsize;
};

-static struct mtrr_value mtrr_value[MTRR_MAX_VAR_RANGES];
+static struct mtrr_value *mtrr_value;

static int mtrr_save(void)
{
int i;

+ if (!mtrr_value)
+ return -ENOMEM;
+
for (i = 0; i < num_var_ranges; i++) {
mtrr_if->get(i, &mtrr_value[i].lbase,
&mtrr_value[i].lsize,
@@ -72,6 +76,8 @@ static struct syscore_ops mtrr_syscore_ops = {

void mtrr_register_syscore(void)
{
+ mtrr_value = kcalloc(num_var_ranges, sizeof(*mtrr_value), GFP_KERNEL);
+
/*
* The CPU has no MTRR and seems to not support SMP. They have
* specific drivers, we use a tricky method to support
--
2.35.3