[PATCH 4.9] kaiser: allocate pgd with order 0 when pti=off

[PATCH 4.9] kaiser: allocate pgd with order 0 when pti=off

[Hugh Dickins]

The 4.9.77 version of "x86/pti/efi: broken conversion from efi to kernel
page table" looked nicer than the 4.4.112 version, but was suboptimal on
machines booted with "pti=off" (or on AMD machines): it allocated pgd
with an order 1 page whatever the setting of kaiser_enabled.

Fix that by moving the definition of PGD_ALLOCATION_ORDER from
asm/pgalloc.h to asm/pgtable.h, which already defines kaiser_enabled.

Fixes: 1b92c48a2eeb ("x86/pti/efi: broken conversion from efi to kernel page table")
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: stable@vger.kernel.org
Signed-off-by: Hugh Dickins <hughd@google.com>
---
 arch/x86/include/asm/pgalloc.h | 11 -----------
 arch/x86/include/asm/pgtable.h |  6 ++++++
 2 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h
index 1178a51b77f3..b6d425999f99 100644
--- a/arch/x86/include/asm/pgalloc.h
+++ b/arch/x86/include/asm/pgalloc.h
@@ -27,17 +27,6 @@ static inline void paravirt_release_pud(unsigned long pfn) {}
  */
 extern gfp_t __userpte_alloc_gfp;
 
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
-/*
- * Instead of one PGD, we acquire two PGDs.  Being order-1, it is
- * both 8k in size and 8k-aligned.  That lets us just flip bit 12
- * in a pointer to swap between the two 4k halves.
- */
-#define PGD_ALLOCATION_ORDER 1
-#else
-#define PGD_ALLOCATION_ORDER 0
-#endif
-
 /*
  * Allocate and free page tables.
  */
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 2536f90cd30c..5af0401ccff2 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -20,9 +20,15 @@
 
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 extern int kaiser_enabled;
+/*
+ * Instead of one PGD, we acquire two PGDs.  Being order-1, it is
+ * both 8k in size and 8k-aligned.  That lets us just flip bit 12
+ * in a pointer to swap between the two 4k halves.
+ */
 #else
 #define kaiser_enabled 0
 #endif
+#define PGD_ALLOCATION_ORDER kaiser_enabled
 
 void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd);
 void ptdump_walk_pgd_level_checkwx(void);
-- 
2.16.0.rc1.238.g530d649a79-goog

Patch "kaiser: allocate pgd with order 0 when pti=off" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    kaiser: allocate pgd with order 0 when pti=off

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kaiser-allocate-pgd-with-order-0-when-pti-off.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From hughd@google.com  Mon Feb  5 05:00:13 2018
From: Hugh Dickins <hughd@google.com>
Date: Mon, 29 Jan 2018 18:17:58 -0800
Subject: kaiser: allocate pgd with order 0 when pti=off
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hugh Dickins <hughd@google.com>, Pavel Tatashin <pasha.tatashin@oracle.com>, Steven Sistare <steven.sistare@oracle.com>, Jiri Kosina <jkosina@suse.cz>, stable@vger.kernel.org
Message-ID: <20180130021758.229507-1-hughd@google.com>

From: Hugh Dickins <hughd@google.com>

The 4.9.77 version of "x86/pti/efi: broken conversion from efi to kernel
page table" looked nicer than the 4.4.112 version, but was suboptimal on
machines booted with "pti=off" (or on AMD machines): it allocated pgd
with an order 1 page whatever the setting of kaiser_enabled.

Fix that by moving the definition of PGD_ALLOCATION_ORDER from
asm/pgalloc.h to asm/pgtable.h, which already defines kaiser_enabled.

Fixes: 1b92c48a2eeb ("x86/pti/efi: broken conversion from efi to kernel page table")
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/include/asm/pgalloc.h |   11 -----------
 arch/x86/include/asm/pgtable.h |    6 ++++++
 2 files changed, 6 insertions(+), 11 deletions(-)

--- a/arch/x86/include/asm/pgalloc.h
+++ b/arch/x86/include/asm/pgalloc.h
@@ -27,17 +27,6 @@ static inline void paravirt_release_pud(
  */
 extern gfp_t __userpte_alloc_gfp;
 
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
-/*
- * Instead of one PGD, we acquire two PGDs.  Being order-1, it is
- * both 8k in size and 8k-aligned.  That lets us just flip bit 12
- * in a pointer to swap between the two 4k halves.
- */
-#define PGD_ALLOCATION_ORDER 1
-#else
-#define PGD_ALLOCATION_ORDER 0
-#endif
-
 /*
  * Allocate and free page tables.
  */
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -20,9 +20,15 @@
 
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 extern int kaiser_enabled;
+/*
+ * Instead of one PGD, we acquire two PGDs.  Being order-1, it is
+ * both 8k in size and 8k-aligned.  That lets us just flip bit 12
+ * in a pointer to swap between the two 4k halves.
+ */
 #else
 #define kaiser_enabled 0
 #endif
+#define PGD_ALLOCATION_ORDER kaiser_enabled
 
 void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd);
 void ptdump_walk_pgd_level_checkwx(void);


Patches currently in stable-queue which might be from hughd@google.com are

queue-4.9/kaiser-allocate-pgd-with-order-0-when-pti-off.patch
queue-4.9/x86-pti-make-unpoison-of-pgd-for-trusted-boot-work-for-real.patch
queue-4.9/kaiser-fix-intel_bts-perf-crashes.patch

Re: [PATCH 4.9] kaiser: allocate pgd with order 0 when pti=off

[Pavel Tatashin]

Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>

On 01/29/2018 09:17 PM, Hugh Dickins wrote:
> The 4.9.77 version of "x86/pti/efi: broken conversion from efi to kernel
> page table" looked nicer than the 4.4.112 version, but was suboptimal on
> machines booted with "pti=off" (or on AMD machines): it allocated pgd
> with an order 1 page whatever the setting of kaiser_enabled.
> 
> Fix that by moving the definition of PGD_ALLOCATION_ORDER from
> asm/pgalloc.h to asm/pgtable.h, which already defines kaiser_enabled.
> 
> Fixes: 1b92c48a2eeb ("x86/pti/efi: broken conversion from efi to kernel page table")
> Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
> Cc: Steven Sistare <steven.sistare@oracle.com>
> Cc: Jiri Kosina <jkosina@suse.cz>
> Cc: stable@vger.kernel.org
> Signed-off-by: Hugh Dickins <hughd@google.com>
> ---
>   arch/x86/include/asm/pgalloc.h | 11 -----------
>   arch/x86/include/asm/pgtable.h |  6 ++++++
>   2 files changed, 6 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h
> index 1178a51b77f3..b6d425999f99 100644
> --- a/arch/x86/include/asm/pgalloc.h
> +++ b/arch/x86/include/asm/pgalloc.h
> @@ -27,17 +27,6 @@ static inline void paravirt_release_pud(unsigned long pfn) {}
>    */
>   extern gfp_t __userpte_alloc_gfp;
>   
> -#ifdef CONFIG_PAGE_TABLE_ISOLATION
> -/*
> - * Instead of one PGD, we acquire two PGDs.  Being order-1, it is
> - * both 8k in size and 8k-aligned.  That lets us just flip bit 12
> - * in a pointer to swap between the two 4k halves.
> - */
> -#define PGD_ALLOCATION_ORDER 1
> -#else
> -#define PGD_ALLOCATION_ORDER 0
> -#endif
> -
>   /*
>    * Allocate and free page tables.
>    */
> diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
> index 2536f90cd30c..5af0401ccff2 100644
> --- a/arch/x86/include/asm/pgtable.h
> +++ b/arch/x86/include/asm/pgtable.h
> @@ -20,9 +20,15 @@
>   
>   #ifdef CONFIG_PAGE_TABLE_ISOLATION
>   extern int kaiser_enabled;
> +/*
> + * Instead of one PGD, we acquire two PGDs.  Being order-1, it is
> + * both 8k in size and 8k-aligned.  That lets us just flip bit 12
> + * in a pointer to swap between the two 4k halves.
> + */
>   #else
>   #define kaiser_enabled 0
>   #endif
> +#define PGD_ALLOCATION_ORDER kaiser_enabled
>   
>   void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd);
>   void ptdump_walk_pgd_level_checkwx(void);
> 

Re: [PATCH 4.9] kaiser: allocate pgd with order 0 when pti=off

[Greg Kroah-Hartman]

On Mon, Feb 05, 2018 at 10:52:00AM -0500, Pavel Tatashin wrote:
> Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>

Wonderful, thanks for the review.

greg k-h