Re: [PATCH v3 5/7] iommu/arm-smmu-v3: Populate smmu_domain->invs when attaching masters

kernel test robot
2025-10-17T16:06:45Z

Hi Nicolin,

kernel test robot noticed the following build warnings:

[auto build test WARNING on soc/for-next]
[also build test WARNING on linus/master v6.18-rc1 next-20251016]
[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#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Nicolin-Chen/iommu-arm-smmu-v3-Explicitly-set-smmu_domain-stage-for-SVA/20251016-034754
base: https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git for-next
patch link: https://lore.kernel.org/r/14d76eebae359825442a96c0ffa13687de792063.1760555863.git.nicolinc%40nvidia.com
patch subject: [PATCH v3 5/7] iommu/arm-smmu-v3: Populate smmu_domain->invs when attaching masters
config: arm64-randconfig-r123-20251017 (https://download.01.org/0day-ci/archive/20251017/202510172340.XyneWIPI-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 754ebc6ebb9fb9fbee7aef33478c74ea74949853)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251017/202510172340.XyneWIPI-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510172340.XyneWIPI-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3208:33: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct arm_smmu_invs **invs_ptr @@ got struct arm_smmu_invs [noderef] __rcu ** @@
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3208:33: sparse: expected struct arm_smmu_invs **invs_ptr
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3208:33: sparse: got struct arm_smmu_invs [noderef] __rcu **
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3226:33: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct arm_smmu_invs **invs_ptr @@ got struct arm_smmu_invs [noderef] __rcu ** @@
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3226:33: sparse: expected struct arm_smmu_invs **invs_ptr
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3226:33: sparse: got struct arm_smmu_invs [noderef] __rcu **
>> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3247:9: sparse: sparse: incompatible types in comparison expression (different address spaces):
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3247:9: sparse: struct arm_smmu_invs [noderef] __rcu *
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3247:9: sparse: struct arm_smmu_invs *
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3305:9: sparse: sparse: incompatible types in comparison expression (different address spaces):
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3305:9: sparse: struct arm_smmu_invs [noderef] __rcu *
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3305:9: sparse: struct arm_smmu_invs *
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c: note: in included file (through arch/arm64/include/asm/atomic.h, include/linux/atomic.h, include/asm-generic/bitops/atomic.h, ...):
arch/arm64/include/asm/cmpxchg.h:168:1: sparse: sparse: cast truncates bits from constant value (ffffffff80000000 becomes 0)
arch/arm64/include/asm/cmpxchg.h:168:1: sparse: sparse: cast truncates bits from constant value (ffffffff80000000 becomes 0)
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c: note: in included file:
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:1056:9: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct callback_head *head @@ got struct callback_head [noderef] __rcu * @@
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:1056:9: sparse: expected struct callback_head *head
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:1056:9: sparse: got struct callback_head [noderef] __rcu *
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:1056:9: sparse: sparse: cast removes address space '__rcu' of expression
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:1056:9: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct callback_head *head @@ got struct callback_head [noderef] __rcu * @@
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:1056:9: sparse: expected struct callback_head *head
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:1056:9: sparse: got struct callback_head [noderef] __rcu *
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:1056:9: sparse: sparse: cast removes address space '__rcu' of expression

vim +3208 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

3174
3175 /*
3176 * During attachment, the updates of the two domain->invs arrays are sequenced:
3177 * 1. new domain updates its invs array, merging master->build_invs
3178 * 2. new domain starts to include the master during its invalidation
3179 * 3. master updates its STE switching from the old domain to the new domain
3180 * 4. old domain still includes the master during its invalidation
3181 * 5. old domain updates its invs array, unreferencing master->build_invs
3182 *
3183 * For 1 and 5, prepare the two updated arrays in advance, handling any changes
3184 * that can possibly failure. So the actual update of either 1 or 5 won't fail.
3185 * arm_smmu_asid_lock ensures that the old invs in the domains are intact while
3186 * we are sequencing to update them.
3187 */
3188 static int arm_smmu_attach_prepare_invs(struct arm_smmu_attach_state *state,
3189 struct arm_smmu_domain *new_smmu_domain)
3190 {
3191 struct arm_smmu_domain *old_smmu_domain =
3192 to_smmu_domain_devices(state->old_domain);
3193 struct arm_smmu_master *master = state->master;
3194 ioasid_t ssid = state->ssid;
3195
3196 /* A re-attach case doesn't need to update invs array */
3197 if (new_smmu_domain == old_smmu_domain)
3198 return 0;
3199
3200 /*
3201 * At this point a NULL domain indicates the domain doesn't use the
3202 * IOTLB, see to_smmu_domain_devices().
3203 */
3204 if (new_smmu_domain) {
3205 struct arm_smmu_inv_state *invst = &state->new_domain_invst;
3206 struct arm_smmu_invs *build_invs;
3207
> 3208 invst->invs_ptr = &new_smmu_domain->invs;
3209 invst->old_invs = rcu_dereference_protected(
3210 new_smmu_domain->invs,
3211 lockdep_is_held(&arm_smmu_asid_lock));
3212 build_invs = arm_smmu_master_build_invs(
3213 master, state->ats_enabled, ssid, new_smmu_domain);
3214 if (!build_invs)
3215 return -EINVAL;
3216
3217 invst->new_invs =
3218 arm_smmu_invs_merge(invst->old_invs, build_invs);
3219 if (IS_ERR(invst->new_invs))
3220 return PTR_ERR(invst->new_invs);
3221 }
3222
3223 if (old_smmu_domain) {
3224 struct arm_smmu_inv_state *invst = &state->old_domain_invst;
3225
3226 invst->invs_ptr = &old_smmu_domain->invs;
3227 invst->old_invs = rcu_dereference_protected(
3228 old_smmu_domain->invs,
3229 lockdep_is_held(&arm_smmu_asid_lock));
3230 /* For old_smmu_domain, new_invs points to master->build_invs */
3231 invst->new_invs = arm_smmu_master_build_invs(
3232 master, master->ats_enabled, ssid, old_smmu_domain);
3233 }
3234
3235 return 0;
3236 }
3237
3238 /* Must be installed before arm_smmu_install_ste_for_dev() */
3239 static void
3240 arm_smmu_install_new_domain_invs(struct arm_smmu_attach_state *state)
3241 {
3242 struct arm_smmu_inv_state *invst = &state->new_domain_invst;
3243
3244 if (!invst->invs_ptr)
3245 return;
3246
> 3247 rcu_assign_pointer(*invst->invs_ptr, invst->new_invs);
3248 /*
3249 * We are committed to updating the STE. Ensure the invalidation array
3250 * is visable to concurrent map/unmap threads, and acquire any racying
3251 * IOPTE updates.
3252 */
3253 smp_mb();
3254 kfree_rcu(invst->old_invs, rcu);
3255 }
3256

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