From: Thomas Hellstrom <[email protected]>
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 <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Christian König <[email protected]>
Cc: Marek Szyprowski <[email protected]>
Cc: Tom Lendacky <[email protected]>
Signed-off-by: Thomas Hellstrom <[email protected]>
---
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
On 9/17/19 6:01 AM, Thomas Hellström (VMware) wrote:
> 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)
My only nit with what remains is that it expands the infestation of
things that look like a simple macro but are not.
I'm debating whether we want to go fix that now, though.
Hi,
On 9/18/19 7:57 PM, Dave Hansen wrote:
> On 9/17/19 6:01 AM, Thomas Hellstr?m (VMware) wrote:
>> 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)
> My only nit with what remains is that it expands the infestation of
> things that look like a simple macro but are not.
>
> I'm debating whether we want to go fix that now, though.
>
Any chance for an ack on this? It's really a small change that, as we've
found out, fixes an existing problem.
Thanks,
Thomas
On 9/30/19 10:54 PM, Thomas Hellstrom wrote:
> Hi,
>
> On 9/18/19 7:57 PM, Dave Hansen wrote:
>> On 9/17/19 6:01 AM, Thomas Hellström (VMware) wrote:
>>> 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)
>> My only nit with what remains is that it expands the infestation of
>> things that look like a simple macro but are not.
>>
>> I'm debating whether we want to go fix that now, though.
>>
> Any chance for an ack on this? It's really a small change that, as we've
> found out, fixes an existing problem.
Yes, feel free to add:
Reviewed-by: Dave Hansen <[email protected]>