Re: [PATCH v6 03/14] KVM: X86: Don't track dirty for KVM_SET_[TSS_ADDR|IDENTITY_MAP_ADDR]
From: Peter Xu
Date: Wed Mar 11 2020 - 12:39:26 EST
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.
Thanks,
> arch/x86/kvm/x86.c:9794:31: sparse: expected void [noderef] <asn:1> *
> arch/x86/kvm/x86.c:9794:31: sparse: got void *
> arch/x86/kvm/x86.c:9799:39: sparse: sparse: incorrect type in return expression (different address spaces) @@ expected void [noderef] <asn:1> * @@ got n:1> * @@
> arch/x86/kvm/x86.c:9799:39: sparse: expected void [noderef] <asn:1> *
> arch/x86/kvm/x86.c:9799:39: sparse: got void *
> arch/x86/kvm/x86.c:9811:39: sparse: sparse: incorrect type in return expression (different address spaces) @@ expected void [noderef] <asn:1> * @@ got n:1> * @@
> arch/x86/kvm/x86.c:9811:39: sparse: expected void [noderef] <asn:1> *
> arch/x86/kvm/x86.c:9811:39: sparse: got void *
> arch/x86/kvm/x86.c:9827:39: sparse: sparse: incorrect type in return expression (different address spaces) @@ expected void [noderef] <asn:1> * @@ got n:1> * @@
> arch/x86/kvm/x86.c:9827:39: sparse: expected void [noderef] <asn:1> *
> arch/x86/kvm/x86.c:9827:39: sparse: got void *
> arch/x86/kvm/x86.c:9863:16: sparse: sparse: incompatible types in comparison expression (different address spaces):
> arch/x86/kvm/x86.c:9863:16: sparse: struct kvm_apic_map [noderef] <asn:4> *
> arch/x86/kvm/x86.c:9863:16: sparse: struct kvm_apic_map *
> arch/x86/kvm/x86.c:9864:15: sparse: sparse: incompatible types in comparison expression (different address spaces):
> arch/x86/kvm/x86.c:9864:15: sparse: struct kvm_pmu_event_filter [noderef] <asn:4> *
> arch/x86/kvm/x86.c:9864:15: sparse: struct kvm_pmu_event_filter *
> include/linux/srcu.h:179:9: sparse: sparse: context imbalance in 'vcpu_enter_guest' - unexpected unlock
>
> vim +9794 arch/x86/kvm/x86.c
>
> 9758
> 9759 /**
> 9760 * __x86_set_memory_region: Setup KVM internal memory slot
> 9761 *
> 9762 * @kvm: the kvm pointer to the VM.
> 9763 * @id: the slot ID to setup.
> 9764 * @gpa: the GPA to install the slot (unused when @size == 0).
> 9765 * @size: the size of the slot. Set to zero to uninstall a slot.
> 9766 *
> 9767 * This function helps to setup a KVM internal memory slot. Specify
> 9768 * @size > 0 to install a new slot, while @size == 0 to uninstall a
> 9769 * slot. The return code can be one of the following:
> 9770 *
> 9771 * - An error number if error happened, or,
> 9772 * - For installation: the HVA of the newly mapped memory slot, or,
> 9773 * - For uninstallation: zero if we successfully uninstall a slot.
> 9774 *
> 9775 * The caller should always use IS_ERR() to check the return value
> 9776 * before use. NOTE: KVM internal memory slots are guaranteed and
> 9777 * won't change until the VM is destroyed. This is also true to the
> 9778 * returned HVA when installing a new memory slot. The HVA can be
> 9779 * invalidated by either an errornous userspace program or a VM under
> 9780 * destruction, however as long as we use __copy_{to|from}_user()
> 9781 * properly upon the HVAs and handle the failure paths always then
> 9782 * we're safe.
> 9783 */
> 9784 void __user * __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa,
> 9785 u32 size)
> 9786 {
> 9787 int i, r;
> 9788 unsigned long hva;
> 9789 struct kvm_memslots *slots = kvm_memslots(kvm);
> 9790 struct kvm_memory_slot *slot, old;
> 9791
> 9792 /* Called with kvm->slots_lock held. */
> 9793 if (WARN_ON(id >= KVM_MEM_SLOTS_NUM))
> > 9794 return ERR_PTR(-EINVAL);
> 9795
> 9796 slot = id_to_memslot(slots, id);
> 9797 if (size) {
> 9798 if (slot->npages)
> 9799 return ERR_PTR(-EEXIST);
> 9800
> 9801 /*
> 9802 * MAP_SHARED to prevent internal slot pages from being moved
> 9803 * by fork()/COW.
> 9804 */
> 9805 hva = vm_mmap(NULL, 0, size, PROT_READ | PROT_WRITE,
> 9806 MAP_SHARED | MAP_ANONYMOUS, 0);
> 9807 if (IS_ERR((void *)hva))
> 9808 return (void __user *)hva;
> 9809 } else {
> 9810 if (!slot->npages)
> 9811 return ERR_PTR(0);
> 9812
> 9813 hva = 0;
> 9814 }
> 9815
> 9816 old = *slot;
> 9817 for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
> 9818 struct kvm_userspace_memory_region m;
> 9819
> 9820 m.slot = id | (i << 16);
> 9821 m.flags = 0;
> 9822 m.guest_phys_addr = gpa;
> 9823 m.userspace_addr = hva;
> 9824 m.memory_size = size;
> 9825 r = __kvm_set_memory_region(kvm, &m);
> 9826 if (r < 0)
> 9827 return ERR_PTR(r);
> 9828 }
> 9829
> 9830 if (!size)
> 9831 vm_munmap(old.userspace_addr, old.npages * PAGE_SIZE);
> 9832
> 9833 return (void __user *)hva;
> 9834 }
> 9835 EXPORT_SYMBOL_GPL(__x86_set_memory_region);
> 9836
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx
>
--
Peter Xu