From: Thomas Hellstrom thellstrom@vmware.com
[ Upstream commit 6db73f17c5f155dbcfd5e48e621c706270b84df0 ]
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.
Signed-off-by: Thomas Hellstrom thellstrom@vmware.com Signed-off-by: Borislav Petkov bp@suse.de Reviewed-by: Dave Hansen dave.hansen@linux.intel.com Acked-by: Tom Lendacky thomas.lendacky@amd.com Link: https://lkml.kernel.org/r/20200304114527.3636-2-thomas_os@shipmail.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 ad97dc1551959..9de80cbdd887e 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 b5e49e6bac635..8267dd426b152 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)
/*