linux-next: kvm/powerpc tree build failure

linux-next: kvm/powerpc tree build failure

[Stephen Rothwell]

Hi Avi, Ben,

Today's linux-next build (powerpc ppc44x_defconfig) failed like this:

cc1: warnings being treated as errors
arch/powerpc/kvm/../../../virt/kvm/kvm_main.c: In function '__kvm_set_memory_region':
arch/powerpc/kvm/../../../virt/kvm/kvm_main.c:1178: error: integer overflow in expression

Probably caused by commit ac04527f7947020c5890090b2ac87af4e98d977e ("KVM:
Disable large pages on misaligned memory slots"). The build fails because
arch/powerpc is now being built (mostly) with -Werror.

arch/powerpc/include/asm/kvm_host.h:#define KVM_PAGES_PER_HPAGE (1<<31)

this needs to be (1UL << 31) or ((unsigned int)1 << 31).

I applied the following patch for today.

From: Stephen Rothwell <sfr@canb.auug.org.au>
Date: Wed, 17 Jun 2009 14:57:29 +1000
Subject: [PATCH] kvm/powerpc: make 32 bit constant unsigned long

KVM_PAGES_PER_HPAGE needs to be unsigned long since its value is 2^31.

Eliminates this compiler warning:

arch/powerpc/kvm/../../../virt/kvm/kvm_main.c:1178: error: integer overflow in expression

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
---
 arch/powerpc/include/asm/kvm_host.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 3625424..d4caa61 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -34,7 +34,7 @@
 #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
 
 /* We don't currently support large pages. */
-#define KVM_PAGES_PER_HPAGE (1<<31)
+#define KVM_PAGES_PER_HPAGE (1UL << 31)
 
 struct kvm;
 struct kvm_run;
-- 
1.6.3.1

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au

Re: linux-next: kvm/powerpc tree build failure

[Avi Kivity]

On 06/17/2009 08:04 AM, Stephen Rothwell wrote:
> From: Stephen Rothwell<sfr@canb.auug.org.au>
> Date: Wed, 17 Jun 2009 14:57:29 +1000
> Subject: [PATCH] kvm/powerpc: make 32 bit constant unsigned long
>
> KVM_PAGES_PER_HPAGE needs to be unsigned long since its value is 2^31.
>
> Eliminates this compiler warning:
>
>    

Thanks, applied.  For some reason my own build testing didn't fail on this.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

Re: linux-next: kvm/powerpc tree build failure

[Stephen Rothwell]

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Hi Avi,

On Wed, 17 Jun 2009 16:49:51 +0300 Avi Kivity <avi@redhat.com> wrote:
>
> Thanks, applied.  For some reason my own build testing didn't fail on this.

Thanks.  It could be a different compiler version doesn't complain (I am
currently using 4.4.0) and the powerpc tree has a patch to build parts of
arch/powerpc with -Werror which makes it stand out a bit :-)

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/

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Re: linux-next: kvm/powerpc tree build failure

[Avi Kivity]

On 06/17/2009 04:55 PM, Stephen Rothwell wrote:
> Hi Avi,
>
> On Wed, 17 Jun 2009 16:49:51 +0300 Avi Kivity<avi@redhat.com>  wrote:
>    
>> Thanks, applied.  For some reason my own build testing didn't fail on this.
>>      
>
> Thanks.  It could be a different compiler version doesn't complain (I am
> currently using 4.4.0) and the powerpc tree has a patch to build parts of
> arch/powerpc with -Werror which makes it stand out a bit :-)
>    

Ah yes, you did mention it was a warning.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.