Messages in this thread | | | From | "Lendacky, Thomas" <> | Subject | Re: [PATCH v2 1/2] x86: Don't let pgprot_modify() change the page encryption bit | Date | Wed, 11 Sep 2019 13:27:08 +0000 |
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On 9/11/19 7:40 AM, Thomas Hellström (VMware) wrote: > From: Thomas Hellstrom <thellstrom@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.hansen@linux.intel.com> > Cc: Andy Lutomirski <luto@kernel.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Borislav Petkov <bp@alien8.de> > Cc: "H. Peter Anvin" <hpa@zytor.com> > Cc: Christoph Hellwig <hch@infradead.org> > Cc: Christian König <christian.koenig@amd.com> > Cc: Marek Szyprowski <m.szyprowski@samsung.com> > Cc: Tom Lendacky <thomas.lendacky@amd.com> > Signed-off-by: Thomas Hellstrom <thellstrom@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..e13084b3d6cb 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 | sme_me_mask)
There is a _PAGE_ENC definition that you could use to make this more consistent with the current definition.
Thanks, Tom
> #define _HPAGE_CHG_MASK (_PAGE_CHG_MASK | _PAGE_PSE) > > /* >
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