From: Thomas Hellstrom <thellst...@vmware.com>
When SEV or SME is enabled and active, vm_get_page_prot() typically
returns with the encryption bit set. This means that users of
pgprot_modify(, vm_get_page_prot()) (mprotect_fixup, do_mmap) end up with
a value of vma->vm_pg_prot that is not consistent with the intended
protection of the PTEs. This is also important for fault handlers that
rely on the VMA vm_page_prot to set the page protection. Fix this by
not allowing pgprot_modify() to change the encryption bit, similar to
how it's done for PAT bits.
Cc: Dave Hansen <dave.han...@linux.intel.com>
Cc: Andy Lutomirski <l...@kernel.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Borislav Petkov <b...@alien8.de>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: Christoph Hellwig <h...@infradead.org>
Cc: Christian König <christian.koe...@amd.com>
Cc: Marek Szyprowski <m.szyprow...@samsung.com>
Cc: Tom Lendacky <thomas.lenda...@amd.com>
Signed-off-by: Thomas Hellstrom <thellst...@vmware.com>
---
arch/x86/include/asm/pgtable.h | 7 +++++--
arch/x86/include/asm/pgtable_types.h | 2 +-
2 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 0bc530c4eb13..1e6bb4c25334 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -624,12 +624,15 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t
newprot)
return __pmd(val);
}
-/* mprotect needs to preserve PAT bits when updating vm_page_prot */
+/*
+ * mprotect needs to preserve PAT and encryption bits when updating
+ * vm_page_prot
+ */
#define pgprot_modify pgprot_modify
static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
{
pgprotval_t preservebits = pgprot_val(oldprot) & _PAGE_CHG_MASK;
- pgprotval_t addbits = pgprot_val(newprot);
+ pgprotval_t addbits = pgprot_val(newprot) & ~_PAGE_CHG_MASK;
return __pgprot(preservebits | addbits);
}
diff --git a/arch/x86/include/asm/pgtable_types.h
b/arch/x86/include/asm/pgtable_types.h
index b5e49e6bac63..8267dd426b15 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -123,7 +123,7 @@
*/
#define _PAGE_CHG_MASK (PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT | \
_PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY | \
- _PAGE_SOFT_DIRTY | _PAGE_DEVMAP)
+ _PAGE_SOFT_DIRTY | _PAGE_DEVMAP | _PAGE_ENC)
#define _HPAGE_CHG_MASK (_PAGE_CHG_MASK | _PAGE_PSE)
/*
--
2.20.1
