From: Yujie Liu <yujie.liu@intel.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
kernel test robot <lkp@intel.com>,
<oe-kbuild-all@lists.linux.dev>, <linux-kernel@vger.kernel.org>,
"Paolo Bonzini" <pbonzini@redhat.com>, <kvm@vger.kernel.org>
Subject: Re: arch/x86/kvm/vmx/hyperv.h:79:30: sparse: sparse: cast truncates bits from constant value (1b009b becomes 9b)
Date: Fri, 1 Dec 2023 14:10:51 +0800 [thread overview]
Message-ID: <ZWl466DIxhF7uRnP@yujie-X299> (raw)
In-Reply-To: <ZWjLN3As3vz5lXcK@google.com>
On Thu, Nov 30, 2023 at 09:49:43AM -0800, Sean Christopherson wrote:
> On Thu, Nov 30, 2023, Vitaly Kuznetsov wrote:
> > kernel test robot <lkp@intel.com> writes:
> >
> > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > > head: 3b47bc037bd44f142ac09848e8d3ecccc726be99
> > > commit: a789aeba419647c44d7e7320de20fea037c211d0 KVM: VMX: Rename "vmx/evmcs.{ch}" to "vmx/hyperv.{ch}"
> > > date: 1 year ago
> > > config: x86_64-randconfig-123-20231130 (https://download.01.org/0day-ci/archive/20231130/202311302231.sinLrAig-lkp@intel.com/config)
> > > compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07)
> > > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231130/202311302231.sinLrAig-lkp@intel.com/reproduce)
> > >
> > > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > > the same patch/commit), kindly add following tags
> > > | Reported-by: kernel test robot <lkp@intel.com>
> > > | Closes: https://lore.kernel.org/oe-kbuild-all/202311302231.sinLrAig-lkp@intel.com/
> > >
> > > sparse warnings: (new ones prefixed by >>)
> > > arch/x86/kvm/vmx/hyperv.h:79:30: sparse: sparse: cast truncates bits from constant value (a000a becomes a)
> >
> > This is what ROL16() macro does but the thing is: we actually want to
> > truncate bits by doing an explicit (u16) cast. We can probably replace
> > this with '& 0xffff':
> >
> > #define ROL16(val, n) ((((u16)(val) << (n)) | ((u16)(val) >> (16 - (n)))) & 0xffff)
> >
> > but honestly I don't see much point...
>
> Yeah, just ignore 'em, we get the exact same sparse complaints in vmcs12.c and
> have had great success ignoring those too :-)
Thanks for the information. We've disabled this warning in the bot to
avoid sending reports against other files with similar code.
Best Regards,
Yujie
next prev parent reply other threads:[~2023-12-01 6:15 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-30 14:14 arch/x86/kvm/vmx/hyperv.h:79:30: sparse: sparse: cast truncates bits from constant value (1b009b becomes 9b) kernel test robot
2023-11-30 16:37 ` Vitaly Kuznetsov
2023-11-30 17:49 ` Sean Christopherson
2023-12-01 6:10 ` Yujie Liu [this message]
2023-12-01 15:56 ` Sean Christopherson
2024-01-10 3:10 ` Yujie Liu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZWl466DIxhF7uRnP@yujie-X299 \
--to=yujie.liu@intel.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=lkp@intel.com \
--cc=oe-kbuild-all@lists.linux.dev \
--cc=pbonzini@redhat.com \
--cc=seanjc@google.com \
--cc=vkuznets@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).