Re: [PATCH v2 2/5] KVM: x86: hyperv: introduce vp_index_to_vcpu_idx mapping

kbuild test robot
2018-06-28T18:49:43Z

Hi Vitaly,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on kvm/linux-next]
[also build test WARNING on v4.18-rc2 next-20180628]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Vitaly-Kuznetsov/KVM-x86-hyperv-PV-IPI-support-for-Windows-guests/20180629-011544
base: https://git.kernel.org/pub/scm/virt/kvm/kvm.git linux-next
reproduce:
# apt-get install sparse
make ARCH=x86_64 allmodconfig
make C=1 CF=-D__CHECK_ENDIAN__

sparse warnings: (new ones prefixed by >>)

>> arch/x86/kvm/hyperv.c:156:15: sparse: incompatible types in comparison expression (different address spaces)
arch/x86/kvm/hyperv.c:195:15: sparse: incompatible types in comparison expression (different address spaces)

vim +156 arch/x86/kvm/hyperv.c

136
137 static u32 vp_idx_to_vcpu_idx(struct kvm *kvm, u32 vp_idx)
138 {
139 struct kvm_hv *hv = &kvm->arch.hyperv;
140 u32 vcpu_idx = U32_MAX, tmp_vp_idx;
141 int l_index = 0, r_index, tmp_index;
142 struct vp_idx_map *map;
143
144 /*
145 * Make an educated guess: vp_idx is initialized to == vcpu_idx, it
146 * stays this way unless changed by userspace.
147 */
148 if (vp_idx < KVM_MAX_VCPUS) {
149 struct kvm_vcpu *vcpu = kvm_get_vcpu(kvm, vp_idx);
150
151 if (vcpu && vcpu_to_hv_vcpu(vcpu)->vp_index == vp_idx)
152 return vp_idx;
153 }
154
155 rcu_read_lock();
> 156 map = rcu_dereference(hv->vp_idx_map);
157 if (!map)
158 goto unlock;
159
160 r_index = map->len - 1;
161
162 while (r_index >= l_index) {
163 tmp_index = (r_index + l_index)/2;
164 tmp_vp_idx = map->vp_idx_elem[tmp_index].vp_idx;
165
166 if (tmp_vp_idx == vp_idx) {
167 vcpu_idx = map->vp_idx_elem[tmp_index].vcpu_idx;
168 break;
169 } else if (tmp_vp_idx < vp_idx) {
170 l_index = tmp_index + 1;
171 } else /* (tmp_vp_idx > vp_idx) */ {
172 r_index = tmp_index - 1;
173 }
174 };
175
176 unlock:
177 rcu_read_unlock();
178
179 return vcpu_idx;
180 }
181

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