[PATCH 3/9] x86/mm/pat: don't populate page tables in set_memory_{en,de}crypted()

["Mike Rapoport (Microsoft)" <rppt@kernel.org>]

__set_memory_enc_pgtable() sets cpa.pgd to init_mm.pgd. With cpa.pgd
set, CPA populates holes in init_mm instead of failing, and
__cpa_process_fault() says that only EFI does that.

So when an address in the range is not mapped, the request does not
fail. populate_pgd() maps the physical memory at cpa.pfn there, with
_KERNPG_TABLE and the encryption bits: present, writable and executable.

A caller that passes an unmapped address is buggy, but it must not get a
new mapping of some random physical memory.

Drop the assignment. The request then walks init_mm as usual: a hole in
the direct map is skipped and any other unmapped address fails with
-EFAULT, as for the other set_memory APIs.

Fixes: 77bd2342d430 ("x86/mm: Add support for changing the memory encryption attribute")
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
 arch/x86/mm/pat/set_memory.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index fb2413cb8d314..aa7052d247e60 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -2457,7 +2457,6 @@ static int __set_memory_enc_pgtable(unsigned long addr, int numpages, bool enc)
 	cpa.numpages = numpages;
 	cpa.mask_set = enc ? pgprot_encrypted(empty) : pgprot_decrypted(empty);
 	cpa.mask_clr = enc ? pgprot_decrypted(empty) : pgprot_encrypted(empty);
-	cpa.pgd = init_mm.pgd;
 
 	/* Must avoid aliasing mappings in the highmem code */
 	kmap_flush_unused();

-- 
2.53.0