Re: [PATCH v3 7/8] KVM: x86/mmu: Protect rmaps independently with SRCU

From: kernel test robot
Date: Thu May 06 2021 - 19:59:41 EST


Hi Ben,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on kvm/queue]
[also build test WARNING on tip/master linus/master next-20210506]
[cannot apply to linux/master v5.12]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url: https://github.com/0day-ci/linux/commits/Ben-Gardon/Lazily-allocate-memslot-rmaps/20210507-024533
base: https://git.kernel.org/pub/scm/virt/kvm/kvm.git queue
config: x86_64-randconfig-s021-20210506 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce:
# apt-get install sparse
# sparse version: v0.6.3-341-g8af24329-dirty
# https://github.com/0day-ci/linux/commit/dd56af97c1d2b22f9acd46d33c83ac5e7bf67acc
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Ben-Gardon/Lazily-allocate-memslot-rmaps/20210507-024533
git checkout dd56af97c1d2b22f9acd46d33c83ac5e7bf67acc
# save the attached .config to linux build tree
make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' W=1 ARCH=x86_64

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>


sparse warnings: (new ones prefixed by >>)
>> arch/x86/kvm/mmu/mmu.c:938:16: sparse: sparse: incompatible types in comparison expression (different address spaces):
>> arch/x86/kvm/mmu/mmu.c:938:16: sparse: struct kvm_rmap_head [noderef] __rcu *
>> arch/x86/kvm/mmu/mmu.c:938:16: sparse: struct kvm_rmap_head *
arch/x86/kvm/mmu/mmu.c: note: in included file (through include/linux/kvm_host.h, arch/x86/kvm/irq.h):
arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
arch/x86/include/asm/kvm_host.h:1871:36: sparse: sparse: marked inline, but without a definition
--
arch/x86/kvm/x86.c:10926:17: sparse: sparse: incompatible types in comparison expression (different address spaces):
>> arch/x86/kvm/x86.c:10926:17: sparse: struct kvm_rmap_head [noderef] __rcu *
>> arch/x86/kvm/x86.c:10926:17: sparse: struct kvm_rmap_head *
arch/x86/kvm/x86.c: note: in included file (through include/linux/notifier.h, include/linux/memory_hotplug.h, include/linux/mmzone.h, ...):
include/linux/srcu.h:182:9: sparse: sparse: context imbalance in 'vcpu_enter_guest' - unexpected unlock

vim +938 arch/x86/kvm/mmu/mmu.c

929
930 static struct kvm_rmap_head *__gfn_to_rmap(struct kvm *kvm, gfn_t gfn,
931 int level,
932 struct kvm_memory_slot *slot)
933 {
934 struct kvm_rmap_head *head;
935 unsigned long idx;
936
937 idx = gfn_to_index(gfn, slot->base_gfn, level);
> 938 head = srcu_dereference_check(slot->arch.rmap[level - PG_LEVEL_4K],
939 &kvm->srcu,
940 lockdep_is_held(&kvm->slots_arch_lock));
941 return &head[idx];
942 }
943

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

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