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Subject[RFC 3/3] x86/mm/encrypt: Convert sme_me_mask to patchable constant
Date
We only change sme_me_mask very early in boot. It may be a candidate for
conversion to patchable constant.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/include/asm/mem_encrypt.h | 5 ++++-
arch/x86/kernel/patchable_const.c | 2 ++
arch/x86/mm/mem_encrypt.c | 15 ++++-----------
3 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
index 22c5f3e6f820..4131ddf262f3 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -18,10 +18,13 @@
#include <linux/init.h>

#include <asm/bootparam.h>
+#include <asm/patchable_const.h>

#ifdef CONFIG_AMD_MEM_ENCRYPT

-extern u64 sme_me_mask;
+#define sme_me_mask_DEFAULT 0
+DECLARE_PATCHABLE_CONST_U64(sme_me_mask);
+#define sme_me_mask sme_me_mask_READ()

void sme_encrypt_execute(unsigned long encrypted_kernel_vaddr,
unsigned long decrypted_kernel_vaddr,
diff --git a/arch/x86/kernel/patchable_const.c b/arch/x86/kernel/patchable_const.c
index 8d48c4c101ca..1bf2980d91b4 100644
--- a/arch/x86/kernel/patchable_const.c
+++ b/arch/x86/kernel/patchable_const.c
@@ -90,11 +90,13 @@ int patch_const_u64(unsigned long **start, unsigned long **stop,
}

PATCHABLE_CONST_U64(__PHYSICAL_MASK);
+PATCHABLE_CONST_U64(sme_me_mask);

#ifdef CONFIG_MODULES
/* Add an entry for a constant here if it expected to be seen in the modules */
static const struct const_u64_table const_u64_table[] = {
{"__PHYSICAL_MASK", __PHYSICAL_MASK_DEFAULT, &__PHYSICAL_MASK_CURRENT},
+ {"sme_me_mask", sme_me_mask_DEFAULT, &sme_me_mask_CURRENT},
};

__init_or_module __nostackprotector
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index 5135b59ce6a5..c93b5c5eeccf 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -36,13 +36,6 @@ static char sme_cmdline_arg[] __initdata = "mem_encrypt";
static char sme_cmdline_on[] __initdata = "on";
static char sme_cmdline_off[] __initdata = "off";

-/*
- * Since SME related variables are set early in the boot process they must
- * reside in the .data section so as not to be zeroed out when the .bss
- * section is later cleared.
- */
-u64 sme_me_mask __section(.data) = 0;
-EXPORT_SYMBOL(sme_me_mask);
DEFINE_STATIC_KEY_FALSE(sev_enable_key);
EXPORT_SYMBOL_GPL(sev_enable_key);

@@ -997,7 +990,7 @@ void __init __nostackprotector sme_enable(struct boot_params *bp)
return;

/* SEV state cannot be controlled by a command line option */
- sme_me_mask = me_mask;
+ sme_me_mask_SET(me_mask);
sev_enabled = true;
return;
}
@@ -1028,11 +1021,11 @@ void __init __nostackprotector sme_enable(struct boot_params *bp)
cmdline_find_option(cmdline_ptr, cmdline_arg, buffer, sizeof(buffer));

if (!strncmp(buffer, cmdline_on, sizeof(buffer)))
- sme_me_mask = me_mask;
+ sme_me_mask_SET(me_mask);
else if (!strncmp(buffer, cmdline_off, sizeof(buffer)))
- sme_me_mask = 0;
+ sme_me_mask_SET(0);
else
- sme_me_mask = active_by_default ? me_mask : 0;
+ sme_me_mask_SET(active_by_default ? me_mask : 0);

if (__PHYSICAL_MASK_SET(__PHYSICAL_MASK & ~sme_me_mask)) {
/* Can we handle it? */
--
2.15.1
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