On Wed, Mar 11, 2020 at 10:09:40AM -0700, Sean Christopherson wrote: > On Wed, Mar 11, 2020 at 12:39:06PM -0400, Peter Xu wrote: > > On Wed, Mar 11, 2020 at 09:10:04AM +0800, kbuild test robot wrote: > > > Hi Peter, > > > > > > Thank you for the patch! Perhaps something to improve: > > > > > > [auto build test WARNING on tip/auto-latest] > > > [also build test WARNING on vhost/linux-next linus/master v5.6-rc5 next-20200310] > > > [cannot apply to kvm/linux-next linux/master] > > > [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/20200310-070637 > > > base: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 12481c76713078054f2d043b3ce946e4814ac29f > > > reproduce: > > > # apt-get install sparse > > > # sparse version: v0.6.1-174-g094d5a94-dirty > > > make ARCH=x86_64 allmodconfig > > > make C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' > > > > > > If you fix the issue, kindly add following tag > > > Reported-by: kbuild test robot <lkp@xxxxxxxxx> > > > > > > > > > sparse warnings: (new ones prefixed by >>) > > > > > > arch/x86/kvm/x86.c:2599:38: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected void const [noderef] <asn:1> * @@ got const [noderef] <asn:1> * @@ > > > arch/x86/kvm/x86.c:2599:38: sparse: expected void const [noderef] <asn:1> * > > > arch/x86/kvm/x86.c:2599:38: sparse: got unsigned char [usertype] * > > > arch/x86/kvm/x86.c:7501:15: sparse: sparse: incompatible types in comparison expression (different address spaces): > > > arch/x86/kvm/x86.c:7501:15: sparse: struct kvm_apic_map [noderef] <asn:4> * > > > arch/x86/kvm/x86.c:7501:15: sparse: struct kvm_apic_map * > > > >> arch/x86/kvm/x86.c:9794:31: sparse: sparse: incorrect type in return expression (different address spaces) @@ expected void [noderef] <asn:1> * @@ got n:1> * @@ > > > > I'm not sure on how I can reproduce this locally, and also I'm not > > very sure I understand this warning. I'd be glad to know if anyone > > knows... > > > > If without further hints, I'll try to remove the __user for > > __x86_set_memory_region() and use a cast on the callers next. > > Ah, it's complaining that the ERR_PTR() returns in __x86_set_memory_region() > aren't explicitly casting to a __user pointer. > > Part of me wonders if something along the lines of your original approach > of keeping the "int" return and passing a "void __user **p_hva" would be > cleaner overall, as opposed to having to cast everywhere. The diff would > certainly be smaller. E.g. > > int __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size, > void __user **p_hva) > { > ... > > if (p_hva) > *p_hva = (void __user *)hva; > > return 0; > } Returning an adress still has some advantage on one less param. To avoid going back and forth, I defined ERR_PTR_USR() and used there to fix the sparse warnings. Thanks, -- Peter Xu
