Re: [PATCH v5 10/15] KVM: Add kvm_arch_dirty_ring_size_updated() hook

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] kvm: missing kvm_arch_dirty_ring_size_updated() stub causes build failure
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commit 78c5608c44701deb8c1679c3f53cbd1303655474
Author: Tian Zheng <zhengtian10@huawei.com>

KVM: Add kvm_arch_dirty_ring_size_updated() hook

This commit adds a kvm_arch_dirty_ring_size_updated() hook called right
after kvm->dirty_ring_size is recorded. It provides a weak no-op default
implementation for architectures to override.

> diff --git a/include/linux/kvm_dirty_ring.h b/include/linux/kvm_dirty_ring.h
> index eb10d87adf7d5..c2b922791530d 100644
> --- a/include/linux/kvm_dirty_ring.h
> +++ b/include/linux/kvm_dirty_ring.h
> @@ -73,6 +73,7 @@ static inline void kvm_dirty_ring_free(struct kvm_dirty_ring *ring)
>  #else /* CONFIG_HAVE_KVM_DIRTY_RING */
>  
>  int kvm_cpu_dirty_log_size(struct kvm *kvm);
> +void kvm_arch_dirty_ring_size_updated(struct kvm *kvm);

[Severity: Low]
Does this cause a build failure on architectures that do not define
CONFIG_HAVE_KVM_DIRTY_RING?

The prototype is placed inside the #else block (when the feature is
enabled), but there is no static inline stub provided in the #ifndef
block. Furthermore, virt/kvm/dirty_ring.c (which contains the weak
definition) is not linked when the config is disabled.

[ ... ]

> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 85f42289748dc..d109062f6a1cf 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -5011,6 +5011,7 @@ static int kvm_vm_ioctl_enable_dirty_log_ring(struct kvm *kvm, u32 size)
>  		r = -EINVAL;
>  	} else {
>  		kvm->dirty_ring_size = size;
> +		kvm_arch_dirty_ring_size_updated(kvm);
>  		r = 0;
>  	}

[Severity: Low]
Since kvm_vm_ioctl_enable_dirty_log_ring() is unconditionally compiled,
will calling kvm_arch_dirty_ring_size_updated() here trigger an implicit
function declaration and link error on architectures like s390x or powerpc
that do not enable the dirty ring?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260929103655.85107-1-zhengtian10@huawei.com?part=10