linux-kernel - Re: [PATCH v9 07/14] KVM: Don't allocate dirty bitmap if dirty ring is enabled

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Message-ID: <20200526150547.GC30967@xsang-OptiPlex-9020>
Date:   Tue, 26 May 2020 23:05:47 +0800
From:   kbuild test robot <lkp@...el.com>
To:     Peter Xu <peterx@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     kbuild-all@...ts.01.org, Vitaly Kuznetsov <vkuznets@...hat.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>,
        Christophe de Dinechin <dinechin@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Kevin Tian <kevin.tian@...el.com>, peterx@...hat.com
Subject: Re: [PATCH v9 07/14] KVM: Don't allocate dirty bitmap if dirty ring
 is enabled

Hi Peter,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on vhost/linux-next]
[also build test WARNING on linus/master v5.7-rc7]
[cannot apply to kvm/linux-next tip/auto-latest linux/master next-20200522]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Peter-Xu/KVM-Dirty-ring-interface/20200524-070926
base:   https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next
:::::: branch date: 2 days ago
:::::: commit date: 2 days ago
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce (this is a W=1 build):
        # save the attached .config to linux build tree
        make W=1 ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@...el.com>


cppcheck warnings: (new ones prefixed by >>)

>> arch/x86/kvm/mmu/mmu.c:1280:3: warning: Returning an integer in a function with pointer return type is not portable. [CastIntegerToAddressAtReturn]
     return false;
     ^
   arch/x86/kvm/mmu/mmu.c:3725:9: warning: Redundant initialization for 'root'. The initialized value is overwritten before it is read. [redundantInitialization]
      root = __pa(sp->spt);
           ^
   arch/x86/kvm/mmu/mmu.c:3715:15: note: root is initialized
      hpa_t root = vcpu->arch.mmu->pae_root[i];
                 ^
   arch/x86/kvm/mmu/mmu.c:3725:9: note: root is overwritten
      root = __pa(sp->spt);
           ^
   arch/x86/kvm/mmu/mmu.c:3769:8: warning: Redundant initialization for 'root'. The initialized value is overwritten before it is read. [redundantInitialization]
     root = __pa(sp->spt);
          ^
   arch/x86/kvm/mmu/mmu.c:3758:14: note: root is initialized
     hpa_t root = vcpu->arch.mmu->root_hpa;
                ^
   arch/x86/kvm/mmu/mmu.c:3769:8: note: root is overwritten
     root = __pa(sp->spt);
          ^
   arch/x86/kvm/mmu/mmu.c:4670:15: warning: Clarify calculation precedence for '&' and '?'. [clarifyCalculation]
    const u8 x = BYTE_MASK(ACC_EXEC_MASK);
                 ^
   arch/x86/kvm/mmu/mmu.c:4671:15: warning: Clarify calculation precedence for '&' and '?'. [clarifyCalculation]
    const u8 w = BYTE_MASK(ACC_WRITE_MASK);
                 ^
   arch/x86/kvm/mmu/mmu.c:4672:15: warning: Clarify calculation precedence for '&' and '?'. [clarifyCalculation]
    const u8 u = BYTE_MASK(ACC_USER_MASK);

# https://github.com/0day-ci/linux/commit/2c23bd2b96e30ae3814e3e56f01a6234131cb531
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 2c23bd2b96e30ae3814e3e56f01a6234131cb531
vim +1280 arch/x86/kvm/mmu/mmu.c

b8e8c8303ff28c arch/x86/kvm/mmu.c     Paolo Bonzini   2019-11-04  1269  
5d163b1c9d6e55 arch/x86/kvm/mmu.c     Xiao Guangrong  2011-03-09  1270  static struct kvm_memory_slot *
5d163b1c9d6e55 arch/x86/kvm/mmu.c     Xiao Guangrong  2011-03-09  1271  gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn,
5d163b1c9d6e55 arch/x86/kvm/mmu.c     Xiao Guangrong  2011-03-09  1272  			    bool no_dirty_log)
05da45583de9b3 arch/x86/kvm/mmu.c     Marcelo Tosatti 2008-02-23  1273  {
05da45583de9b3 arch/x86/kvm/mmu.c     Marcelo Tosatti 2008-02-23  1274  	struct kvm_memory_slot *slot;
5d163b1c9d6e55 arch/x86/kvm/mmu.c     Xiao Guangrong  2011-03-09  1275  
54bf36aac52031 arch/x86/kvm/mmu.c     Paolo Bonzini   2015-04-08  1276  	slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
91b0d268a59dd9 arch/x86/kvm/mmu/mmu.c Paolo Bonzini   2020-01-21  1277  	if (!slot || slot->flags & KVM_MEMSLOT_INVALID)
91b0d268a59dd9 arch/x86/kvm/mmu/mmu.c Paolo Bonzini   2020-01-21  1278  		return NULL;
2c23bd2b96e30a arch/x86/kvm/mmu/mmu.c Peter Xu        2020-05-23  1279  	if (no_dirty_log && kvm_slot_dirty_track_enabled(slot))
2c23bd2b96e30a arch/x86/kvm/mmu/mmu.c Peter Xu        2020-05-23 @1280  		return false;
5d163b1c9d6e55 arch/x86/kvm/mmu.c     Xiao Guangrong  2011-03-09  1281  
5d163b1c9d6e55 arch/x86/kvm/mmu.c     Xiao Guangrong  2011-03-09  1282  	return slot;
5d163b1c9d6e55 arch/x86/kvm/mmu.c     Xiao Guangrong  2011-03-09  1283  }
5d163b1c9d6e55 arch/x86/kvm/mmu.c     Xiao Guangrong  2011-03-09  1284  

---
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