WTF: patch "[PATCH] x86: kvm: avoid unused variable warning" was seriously submitted to be applied to the 4.18-stable tree?

WTF: patch "[PATCH] x86: kvm: avoid unused variable warning" was seriously submitted to be applied to the 4.18-stable tree?

[gregkh]

The patch below was submitted to be applied to the 4.18-stable tree.

I fail to see how this patch meets the stable kernel rules as found at
Documentation/process/stable-kernel-rules.rst.

I could be totally wrong, and if so, please respond to 
<stable@vger.kernel.org> and let me know why this patch should be
applied.  Otherwise, it is now dropped from my patch queues, never to be
seen again.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 7288bde1f9df6c1475675419bdd7725ce84dec56 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Mon, 20 Aug 2018 23:37:50 +0200
Subject: [PATCH] x86: kvm: avoid unused variable warning

Removing one of the two accesses of the maxphyaddr variable led to
a harmless warning:

arch/x86/kvm/x86.c: In function 'kvm_set_mmio_spte_mask':
arch/x86/kvm/x86.c:6563:6: error: unused variable 'maxphyaddr' [-Werror=unused-variable]

Removing the #ifdef seems to be the nicest workaround, as it
makes the code look cleaner than adding another #ifdef.

Fixes: 28a1f3ac1d0c ("kvm: x86: Set highest physical address bits in non-present/reserved SPTEs")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: stable@vger.kernel.org # L1TF
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f7dff0457846..14ee9a814888 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6576,14 +6576,12 @@ static void kvm_set_mmio_spte_mask(void)
 	/* Set the present bit. */
 	mask |= 1ull;
 
-#ifdef CONFIG_X86_64
 	/*
 	 * If reserved bit is not supported, clear the present bit to disable
 	 * mmio page fault.
 	 */
-	if (maxphyaddr == 52)
+	if (IS_ENABLED(CONFIG_X86_64) && maxphyaddr == 52)
 		mask &= ~1ull;
-#endif
 
 	kvm_mmu_set_mmio_spte_mask(mask, mask);
 }

Re: WTF: patch "[PATCH] x86: kvm: avoid unused variable warning" was seriously submitted to be applied to the 4.18-stable tree?

[Greg KH]

On Sat, Sep 01, 2018 at 02:24:23PM -0700, gregkh@linuxfoundation.org wrote:
> The patch below was submitted to be applied to the 4.18-stable tree.
> 
> I fail to see how this patch meets the stable kernel rules as found at
> Documentation/process/stable-kernel-rules.rst.

Oops, hit the wrong button, this should have been my "this did not
apply" message, sorry about that.

This doesn't apply because:


> 
> I could be totally wrong, and if so, please respond to 
> <stable@vger.kernel.org> and let me know why this patch should be
> applied.  Otherwise, it is now dropped from my patch queues, never to be
> seen again.
> 
> thanks,
> 
> greg k-h
> 
> ------------------ original commit in Linus's tree ------------------
> 
> >From 7288bde1f9df6c1475675419bdd7725ce84dec56 Mon Sep 17 00:00:00 2001
> From: Arnd Bergmann <arnd@arndb.de>
> Date: Mon, 20 Aug 2018 23:37:50 +0200
> Subject: [PATCH] x86: kvm: avoid unused variable warning
> 
> Removing one of the two accesses of the maxphyaddr variable led to
> a harmless warning:
> 
> arch/x86/kvm/x86.c: In function 'kvm_set_mmio_spte_mask':
> arch/x86/kvm/x86.c:6563:6: error: unused variable 'maxphyaddr' [-Werror=unused-variable]
> 
> Removing the #ifdef seems to be the nicest workaround, as it
> makes the code look cleaner than adding another #ifdef.
> 
> Fixes: 28a1f3ac1d0c ("kvm: x86: Set highest physical address bits in non-present/reserved SPTEs")

that commit is not in a stable tree.  It wasn't marked to be backpoted,
should it?

thanks,

greg k-h

Re: WTF: patch "[PATCH] x86: kvm: avoid unused variable warning" was seriously submitted to be applied to the 4.18-stable tree?

[Arnd Bergmann]

On Sat, Sep 1, 2018 at 11:39 PM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Sat, Sep 01, 2018 at 02:24:23PM -0700, gregkh@linuxfoundation.org wrote:
> > The patch below was submitted to be applied to the 4.18-stable tree.
> >
> > I fail to see how this patch meets the stable kernel rules as found at
> > Documentation/process/stable-kernel-rules.rst.
>
> Oops, hit the wrong button, this should have been my "this did not
> apply" message, sorry about that.
>
> This doesn't apply because:
>
> >
> > Fixes: 28a1f3ac1d0c ("kvm: x86: Set highest physical address bits in non-present/reserved SPTEs")
>
> that commit is not in a stable tree.  It wasn't marked to be backpoted,
> should it?

When I sent my compile fix, I did not expect either one to need a backport.
Looking at 28a1f3ac1d0c more closely does make it sound like it should
be. Junaid Shahid wrote the patch originally, let's see what he thinks.

       Arnd

Re: WTF: patch "[PATCH] x86: kvm: avoid unused variable warning" was seriously submitted to be applied to the 4.18-stable tree?

[Junaid Shahid]

On 09/03/2018 02:27 AM, Arnd Bergmann wrote:
> On Sat, Sep 1, 2018 at 11:39 PM Greg KH <gregkh@linuxfoundation.org> wrote:
>>
>> On Sat, Sep 01, 2018 at 02:24:23PM -0700, gregkh@linuxfoundation.org wrote:
>>> The patch below was submitted to be applied to the 4.18-stable tree.
>>>
>>> I fail to see how this patch meets the stable kernel rules as found at
>>> Documentation/process/stable-kernel-rules.rst.
>>
>> Oops, hit the wrong button, this should have been my "this did not
>> apply" message, sorry about that.
>>
>> This doesn't apply because:
>>
>>>
>>> Fixes: 28a1f3ac1d0c ("kvm: x86: Set highest physical address bits in non-present/reserved SPTEs")
>>
>> that commit is not in a stable tree.  It wasn't marked to be backpoted,
>> should it?
> 
> When I sent my compile fix, I did not expect either one to need a backport.
> Looking at 28a1f3ac1d0c more closely does make it sound like it should
> be. Junaid Shahid wrote the patch originally, let's see what he thinks.
> 
>        Arnd
> 

Yes, I think that it would be a good idea to include 28a1f3ac1d0c in the stable tree, as it contains a security fix related to L1TF.

Thanks,
Junaid

Re: WTF: patch "[PATCH] x86: kvm: avoid unused variable warning" was seriously submitted to be applied to the 4.18-stable tree?

[gregkh]

On Tue, Sep 04, 2018 at 12:17:57PM -0700, Junaid Shahid wrote:
> On 09/03/2018 02:27 AM, Arnd Bergmann wrote:
> > On Sat, Sep 1, 2018 at 11:39 PM Greg KH <gregkh@linuxfoundation.org> wrote:
> >>
> >> On Sat, Sep 01, 2018 at 02:24:23PM -0700, gregkh@linuxfoundation.org wrote:
> >>> The patch below was submitted to be applied to the 4.18-stable tree.
> >>>
> >>> I fail to see how this patch meets the stable kernel rules as found at
> >>> Documentation/process/stable-kernel-rules.rst.
> >>
> >> Oops, hit the wrong button, this should have been my "this did not
> >> apply" message, sorry about that.
> >>
> >> This doesn't apply because:
> >>
> >>>
> >>> Fixes: 28a1f3ac1d0c ("kvm: x86: Set highest physical address bits in non-present/reserved SPTEs")
> >>
> >> that commit is not in a stable tree.  It wasn't marked to be backpoted,
> >> should it?
> > 
> > When I sent my compile fix, I did not expect either one to need a backport.
> > Looking at 28a1f3ac1d0c more closely does make it sound like it should
> > be. Junaid Shahid wrote the patch originally, let's see what he thinks.
> > 
> >        Arnd
> > 
> 
> Yes, I think that it would be a good idea to include 28a1f3ac1d0c in the stable tree, as it contains a security fix related to L1TF.

Ok, now applied to 4.18.y and 4.14.y, thanks.

greg k-h