[PATCH] x86/mm/pat: Fix L1TF stable backport for CPA

[PATCH] x86/mm/pat: Fix L1TF stable backport for CPA

[Andi Kleen]

From: Andi Kleen <ak@linux.intel.com>

Patch for stable only to fix boot resets caused by the L1TF patches.

Stable trees reverted the following patch

Revert "x86/mm/pat: Ensure cpa->pfn only contains page frame numbers"

    This reverts commit 87e2bd898d3a79a8c609f183180adac47879a2a4 which is
    commit edc3b9129cecd0f0857112136f5b8b1bc1d45918 upstream.

but the L1TF patch backported here

   x86/mm/pat: Make set_memory_np() L1TF safe

    commit 958f79b9ee55dfaf00c8106ed1c22a2919e0028b upstream

    set_memory_np() is used to mark kernel mappings not present, but it has
    it's own open coded mechanism which does not have the L1TF protection of
    inverting the address bits.

assumed that cpa->pfn contains a PFN. With the above patch reverted
it does not, which causes the PMD to be set to an incorrect address
shifted by 12 bits, which can cause early boot reset on some
systems, like an Apollo Lake embedded system.

Convert the address to a PFN before passing it to pmd_pfn()

Thanks to Bernhard for bisecting and testing.

Cc: stable@vger.kernel.org # 4.4 and 4.9
Reported-by: Bernhard Kaindl <bernhard.kaindl@thalesgroup.com>
Tested-by: Bernhard Kaindl <bernhard.kaindl@thalesgroup.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 arch/x86/mm/pageattr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 27610c2d1821..1007fa80f5a6 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -1006,7 +1006,7 @@ static int populate_pmd(struct cpa_data *cpa,
 
 		pmd = pmd_offset(pud, start);
 
-		set_pmd(pmd, pmd_mkhuge(pfn_pmd(cpa->pfn,
+		set_pmd(pmd, pmd_mkhuge(pfn_pmd(cpa->pfn >> PAGE_SHIFT,
 					canon_pgprot(pmd_pgprot))));
 
 		start	  += PMD_SIZE;
-- 
2.17.1

Re: [PATCH] x86/mm/pat: Fix L1TF stable backport for CPA

[Greg KH]

On Sat, Aug 25, 2018 at 06:50:15AM -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
> 
> Patch for stable only to fix boot resets caused by the L1TF patches.
> 
> Stable trees reverted the following patch
> 
> Revert "x86/mm/pat: Ensure cpa->pfn only contains page frame numbers"
> 
>     This reverts commit 87e2bd898d3a79a8c609f183180adac47879a2a4 which is
>     commit edc3b9129cecd0f0857112136f5b8b1bc1d45918 upstream.
> 
> but the L1TF patch backported here
> 
>    x86/mm/pat: Make set_memory_np() L1TF safe
> 
>     commit 958f79b9ee55dfaf00c8106ed1c22a2919e0028b upstream
> 
>     set_memory_np() is used to mark kernel mappings not present, but it has
>     it's own open coded mechanism which does not have the L1TF protection of
>     inverting the address bits.
> 
> assumed that cpa->pfn contains a PFN. With the above patch reverted
> it does not, which causes the PMD to be set to an incorrect address
> shifted by 12 bits, which can cause early boot reset on some
> systems, like an Apollo Lake embedded system.
> 
> Convert the address to a PFN before passing it to pmd_pfn()
> 
> Thanks to Bernhard for bisecting and testing.
> 
> Cc: stable@vger.kernel.org # 4.4 and 4.9
> Reported-by: Bernhard Kaindl <bernhard.kaindl@thalesgroup.com>
> Tested-by: Bernhard Kaindl <bernhard.kaindl@thalesgroup.com>
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
>  arch/x86/mm/pageattr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Thanks for this, now queued up.

greg k-h

Re: [PATCH] x86/mm/pat: Fix L1TF stable backport for CPA

[Guenter Roeck]

On Sat, Aug 25, 2018 at 06:50:15AM -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
> 
> Patch for stable only to fix boot resets caused by the L1TF patches.
> 
> Stable trees reverted the following patch
> 
> Revert "x86/mm/pat: Ensure cpa->pfn only contains page frame numbers"
> 
>     This reverts commit 87e2bd898d3a79a8c609f183180adac47879a2a4 which is
>     commit edc3b9129cecd0f0857112136f5b8b1bc1d45918 upstream.
> 
> but the L1TF patch backported here
> 
>    x86/mm/pat: Make set_memory_np() L1TF safe
> 
>     commit 958f79b9ee55dfaf00c8106ed1c22a2919e0028b upstream
> 
>     set_memory_np() is used to mark kernel mappings not present, but it has
>     it's own open coded mechanism which does not have the L1TF protection of
>     inverting the address bits.
> 
> assumed that cpa->pfn contains a PFN. With the above patch reverted
> it does not, which causes the PMD to be set to an incorrect address
> shifted by 12 bits, which can cause early boot reset on some
> systems, like an Apollo Lake embedded system.
> 
> Convert the address to a PFN before passing it to pmd_pfn()
> 
> Thanks to Bernhard for bisecting and testing.
> 

Thanks a lot to you for tracking it down, and sorry for messing it up.

> Cc: stable@vger.kernel.org # 4.4 and 4.9

LGTM for v4.4.y but ... are you sure that this patch applies to v4.9.y ?
Commit edc3b9129cec is 'native' in v4.9.y and has not been reverted there.

$ git log --oneline v4.4..linux-4.9.y | grep "x86/mm/pat: Ensure cpa->pfn only contains page frame numbers"
edc3b9129cec x86/mm/pat: Ensure cpa->pfn only contains page frame numbers

Guenter

> Reported-by: Bernhard Kaindl <bernhard.kaindl@thalesgroup.com>
> Tested-by: Bernhard Kaindl <bernhard.kaindl@thalesgroup.com>
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
>  arch/x86/mm/pageattr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
> index 27610c2d1821..1007fa80f5a6 100644
> --- a/arch/x86/mm/pageattr.c
> +++ b/arch/x86/mm/pageattr.c
> @@ -1006,7 +1006,7 @@ static int populate_pmd(struct cpa_data *cpa,
>  
>  		pmd = pmd_offset(pud, start);
>  
> -		set_pmd(pmd, pmd_mkhuge(pfn_pmd(cpa->pfn,
> +		set_pmd(pmd, pmd_mkhuge(pfn_pmd(cpa->pfn >> PAGE_SHIFT,
>  					canon_pgprot(pmd_pgprot))));
>  
>  		start	  += PMD_SIZE;

Re: [PATCH] x86/mm/pat: Fix L1TF stable backport for CPA

[Andi Kleen]

> > Cc: stable@vger.kernel.org # 4.4 and 4.9
> 
> LGTM for v4.4.y but ... are you sure that this patch applies to v4.9.y ?
> Commit edc3b9129cec is 'native' in v4.9.y and has not been reverted there.

You're right. I thought it was needed for 4.9 too, but yes it has the CPA pfn
patch. So for 4.9 the patch is not needed and in fact incorrect.

The original report was for 4.4.

Greg can you please revert/remove it again for 4.9?

-Andi

Re: [PATCH] x86/mm/pat: Fix L1TF stable backport for CPA

[Greg KH]

On Sat, Aug 25, 2018 at 10:06:41PM -0700, Andi Kleen wrote:
> > > Cc: stable@vger.kernel.org # 4.4 and 4.9
> > 
> > LGTM for v4.4.y but ... are you sure that this patch applies to v4.9.y ?
> > Commit edc3b9129cec is 'native' in v4.9.y and has not been reverted there.
> 
> You're right. I thought it was needed for 4.9 too, but yes it has the CPA pfn
> patch. So for 4.9 the patch is not needed and in fact incorrect.
> 
> The original report was for 4.4.
> 
> Greg can you please revert/remove it again for 4.9?

Now dropped, thanks.

greg k-h

Re: [PATCH] x86/mm/pat: Fix L1TF stable backport for CPA

[Jiri Slaby]

On 08/25/2018, 03:50 PM, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
> 
> Patch for stable only to fix boot resets caused by the L1TF patches.
> 
> Stable trees reverted the following patch
> 
> Revert "x86/mm/pat: Ensure cpa->pfn only contains page frame numbers"
> 
>     This reverts commit 87e2bd898d3a79a8c609f183180adac47879a2a4 which is
>     commit edc3b9129cecd0f0857112136f5b8b1bc1d45918 upstream.
> 
> but the L1TF patch backported here
> 
>    x86/mm/pat: Make set_memory_np() L1TF safe
> 
>     commit 958f79b9ee55dfaf00c8106ed1c22a2919e0028b upstream
> 
>     set_memory_np() is used to mark kernel mappings not present, but it has
>     it's own open coded mechanism which does not have the L1TF protection of
>     inverting the address bits.
> 
> assumed that cpa->pfn contains a PFN. With the above patch reverted
> it does not, which causes the PMD to be set to an incorrect address
> shifted by 12 bits, which can cause early boot reset on some
> systems, like an Apollo Lake embedded system.
> 
> Convert the address to a PFN before passing it to pmd_pfn()
> 
> Thanks to Bernhard for bisecting and testing.
> 
> Cc: stable@vger.kernel.org # 4.4 and 4.9
> Reported-by: Bernhard Kaindl <bernhard.kaindl@thalesgroup.com>
> Tested-by: Bernhard Kaindl <bernhard.kaindl@thalesgroup.com>
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
>  arch/x86/mm/pageattr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
> index 27610c2d1821..1007fa80f5a6 100644
> --- a/arch/x86/mm/pageattr.c
> +++ b/arch/x86/mm/pageattr.c
> @@ -1006,7 +1006,7 @@ static int populate_pmd(struct cpa_data *cpa,
>  
>  		pmd = pmd_offset(pud, start);
>  
> -		set_pmd(pmd, pmd_mkhuge(pfn_pmd(cpa->pfn,
> +		set_pmd(pmd, pmd_mkhuge(pfn_pmd(cpa->pfn >> PAGE_SHIFT,
>  					canon_pgprot(pmd_pgprot))));

And what about populate_pud?
                set_pud(pud, pud_mkhuge(pfn_pud(cpa->pfn,
                                   canon_pgprot(pud_pgprot))));

                start     += PUD_SIZE;
                cpa->pfn  += PUD_SIZE;

thanks,
-- 
js
suse labs

Re: [PATCH] x86/mm/pat: Fix L1TF stable backport for CPA

[Andi Kleen]

> And what about populate_pud?
>                 set_pud(pud, pud_mkhuge(pfn_pud(cpa->pfn,
>                                    canon_pgprot(pud_pgprot))));
> 
>                 start     += PUD_SIZE;
>                 cpa->pfn  += PUD_SIZE;

Yes you're right. That case needs to be fixed too.

Are you sending a patch, or should I?

-Andi

Re: [PATCH] x86/mm/pat: Fix L1TF stable backport for CPA

[Greg KH]

On Thu, Sep 06, 2018 at 01:27:49PM -0700, Andi Kleen wrote:
> > And what about populate_pud?
> >                 set_pud(pud, pud_mkhuge(pfn_pud(cpa->pfn,
> >                                    canon_pgprot(pud_pgprot))));
> > 
> >                 start     += PUD_SIZE;
> >                 cpa->pfn  += PUD_SIZE;
> 
> Yes you're right. That case needs to be fixed too.
> 
> Are you sending a patch, or should I?

Someone needs to.  Please?

greg k-h

Re: [PATCH] x86/mm/pat: Fix L1TF stable backport for CPA

[Jiri Slaby]

On 09/17/2018, 01:51 PM, Greg KH wrote:
> On Thu, Sep 06, 2018 at 01:27:49PM -0700, Andi Kleen wrote:
>>> And what about populate_pud?
>>>                 set_pud(pud, pud_mkhuge(pfn_pud(cpa->pfn,
>>>                                    canon_pgprot(pud_pgprot))));
>>>
>>>                 start     += PUD_SIZE;
>>>                 cpa->pfn  += PUD_SIZE;
>>
>> Yes you're right. That case needs to be fixed too.
>>
>> Are you sending a patch, or should I?
> 
> Someone needs to.  Please?

You already released 4.4.x with the patch :):

commit 15898df477269c981dc1ae5afa39e1bb65e1db0a
Author: Jiri Slaby <jslaby@suse.cz>
Date:   Fri Sep 7 11:13:07 2018 +0200

    x86/mm/pat: Fix L1TF stable backport for CPA, 2nd call

thanks,
-- 
js
suse labs

Re: [PATCH] x86/mm/pat: Fix L1TF stable backport for CPA

[Greg KH]

On Mon, Sep 17, 2018 at 02:16:33PM +0200, Jiri Slaby wrote:
> On 09/17/2018, 01:51 PM, Greg KH wrote:
> > On Thu, Sep 06, 2018 at 01:27:49PM -0700, Andi Kleen wrote:
> >>> And what about populate_pud?
> >>>                 set_pud(pud, pud_mkhuge(pfn_pud(cpa->pfn,
> >>>                                    canon_pgprot(pud_pgprot))));
> >>>
> >>>                 start     += PUD_SIZE;
> >>>                 cpa->pfn  += PUD_SIZE;
> >>
> >> Yes you're right. That case needs to be fixed too.
> >>
> >> Are you sending a patch, or should I?
> > 
> > Someone needs to.  Please?
> 
> You already released 4.4.x with the patch :):
> 
> commit 15898df477269c981dc1ae5afa39e1bb65e1db0a
> Author: Jiri Slaby <jslaby@suse.cz>
> Date:   Fri Sep 7 11:13:07 2018 +0200
> 
>     x86/mm/pat: Fix L1TF stable backport for CPA, 2nd call
> 

Ugh, nevermind, sorry for the noise :)

greg k-h