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Subject[PATCH] x86/mm: Unbreak modules that rely on external PAGE_KERNEL availability
From: Jiri Kosina <jkosina@suse.cz>

Commit

7744ccdbc16f0 ("x86/mm: Add Secure Memory Encryption (SME) support")

as a side-effect made PAGE_KERNEL all of a sudden unavailable to modules
which can't make use of EXPORT_SYMBOL_GPL() symbols.

This is because once SME is enabled, sme_me_mask (which is introduced as
EXPORT_SYMBOL_GPL) makes its way to PAGE_KERNEL through _PAGE_ENC, causing
imminent build failure for all the modules which make use of all the
EXPORT-SYMBOL()-exported API (such as vmap(), __vmalloc(),
remap_pfn_range(), ...).

Exporting (as EXPORT_SYMBOL()) interfaces (and having done so for ages)
that take pgprot_t argument, while making it impossible to -- all of a
sudden -- pass PAGE_KERNEL to it, feels rather incosistent.

Restore the original behavior and make it possible to pass PAGE_KERNEL to
all its EXPORT_SYMBOL() consumers.

Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
---
arch/x86/mm/mem_encrypt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index 16c5f37933a2..0286327e65fa 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -40,7 +40,7 @@ static char sme_cmdline_off[] __initdata = "off";
* section is later cleared.
*/
u64 sme_me_mask __section(.data) = 0;
-EXPORT_SYMBOL_GPL(sme_me_mask);
+EXPORT_SYMBOL(sme_me_mask);

/* Buffer used for early in-place encryption by BSP, no locking needed */
static char sme_early_buffer[PAGE_SIZE] __aligned(PAGE_SIZE);
--
Jiri Kosina
SUSE Labs

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