[avpatel:riscv_trace_support_v5 62/108] arch/riscv/kvm/aia_imsic.c:919:2: warning: variable 'vcpu' is used uninitialized whenever 'if' condition is false

tree:   https://github.com/avpatel/linux.git riscv_trace_support_v5
head:   e58ea3f194d326370813c549a76ecdfa211a4768
commit: ccdd3c493dc8ce3acb64600af8437ebb28775ceb [62/108] RISC-V: KVM: Add guest file irqbypass support
config: riscv-randconfig-r061-20260820 (https://download.01.org/0day-ci/archive/20260820/[email protected]/config)
compiler: clang version 24.0.0git (https://github.com/llvm/llvm-project 935bfc708590c60147a79c7df145bb6e68b1d388)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260820/[email protected]/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 <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All warnings (new ones prefixed by >>):

>> arch/riscv/kvm/aia_imsic.c:919:2: warning: variable 'vcpu' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
     919 |         kvm_for_each_vcpu(tmp, vcpu, kvm) {
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/kvm_host.h:1012:6: note: expanded from macro 'kvm_for_each_vcpu'
    1012 |         if (atomic_read(&kvm->online_vcpus))                            \
         |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   arch/riscv/kvm/aia_imsic.c:923:7: note: uninitialized use occurs here
     923 |         if (!vcpu)
         |              ^~~~
   arch/riscv/kvm/aia_imsic.c:919:2: note: remove the 'if' if its condition is always true
     919 |         kvm_for_each_vcpu(tmp, vcpu, kvm) {
         |         ^
   include/linux/kvm_host.h:1012:2: note: expanded from macro 'kvm_for_each_vcpu'
    1012 |         if (atomic_read(&kvm->online_vcpus))                            \
         |         ^
   arch/riscv/kvm/aia_imsic.c:883:23: note: initialize the variable 'vcpu' to silence this warning
     883 |         struct kvm_vcpu *vcpu;
         |                              ^
         |                               = NULL
   1 warning generated.


vim +919 arch/riscv/kvm/aia_imsic.c

   872	
   873	void kvm_arch_update_irqfd_routing(struct kvm_kernel_irqfd *irqfd,
   874					   struct kvm_kernel_irq_routing_entry *old,
   875					   struct kvm_kernel_irq_routing_entry *new)
   876	{
   877		struct riscv_iommu_ir_vcpu_info vcpu_info;
   878		struct kvm *kvm = irqfd->kvm;
   879		struct kvm_aia *aia = &kvm->arch.aia;
   880		int host_irq;
   881		struct irq_data *irqdata;
   882		unsigned long tmp, flags;
   883		struct kvm_vcpu *vcpu;
   884		struct imsic *imsic;
   885		struct msi_msg msg;
   886		u64 msi_addr_mask;
   887		gpa_t target;
   888		int ret;
   889	
   890		host_irq = irqfd->producer->irq;
   891		irqdata = irq_get_irq_data(host_irq);
   892	
   893		if (old && old->type == KVM_IRQ_ROUTING_MSI &&
   894		    new && new->type == KVM_IRQ_ROUTING_MSI &&
   895		    !memcmp(&old->msi, &new->msi, sizeof(new->msi)))
   896			return;
   897	
   898		if (!new) {
   899			if (!WARN_ON_ONCE(!old) && old->type == KVM_IRQ_ROUTING_MSI) {
   900				ret = irq_set_vcpu_affinity(host_irq, NULL);
   901				WARN_ON_ONCE(ret && ret != -EOPNOTSUPP);
   902			}
   903			return;
   904		}
   905	
   906		if (new->type != KVM_IRQ_ROUTING_MSI)
   907			return;
   908	
   909		target = ((gpa_t)new->msi.address_hi << 32) | new->msi.address_lo;
   910		if (WARN_ON_ONCE(target & (IMSIC_MMIO_PAGE_SZ - 1)))
   911			return;
   912	
   913		msg = (struct msi_msg){
   914			.address_hi = new->msi.address_hi,
   915			.address_lo = new->msi.address_lo,
   916			.data = new->msi.data,
   917		};
   918	
 > 919		kvm_for_each_vcpu(tmp, vcpu, kvm) {
   920			if (target == vcpu->arch.aia_context.imsic_addr)
   921				break;
   922		}
   923		if (!vcpu)
   924			return;
   925	
   926		msi_addr_mask = kvm_riscv_aia_msi_addr_mask(aia);
   927		vcpu_info = (struct riscv_iommu_ir_vcpu_info){
   928			.gpa = target,
   929			.msi_addr_mask = msi_addr_mask,
   930			.msi_addr_pattern = (target >> IMSIC_MMIO_PAGE_SHIFT) & ~msi_addr_mask,
   931			.group_index_bits = aia->nr_group_bits,
   932			.group_index_shift = aia->nr_group_shift,
   933		};
   934	
   935		imsic = vcpu->arch.aia_context.imsic_state;
   936	
   937		read_lock_irqsave(&imsic->vsfile_lock, flags);
   938	
   939		if (imsic->vsfile_cpu < 0)
   940			goto out;
   941	
   942		vcpu_info.hpa = imsic->vsfile_pa;
   943	
   944		ret = irq_set_vcpu_affinity(host_irq, &vcpu_info);
   945		WARN_ON_ONCE(ret && ret != -EOPNOTSUPP);
   946		if (ret)
   947			goto out;
   948	
   949		/*
   950		 * Unlike x86 (which updates the IRTE) and arm64 (which updates
   951		 * the ITS ITTE), RISC-V reprograms the device MSI target address
   952		 * to the guest IMSIC GPA. The device writes to the guest GPA;
   953		 * the IOMMU MSI table maps guest GPA -> host VS-file HPA.
   954		 */
   955		irq_data_get_irq_chip(irqdata)->irq_write_msi_msg(irqdata, &msg);
   956	
   957	out:
   958		read_unlock_irqrestore(&imsic->vsfile_lock, flags);
   959	}
   960	

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