Re: [PATCH v8 04/20] KVM: selftests: Initialize the default/global pRNG during kvm_selftest_init()

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Global PRNG state cannot be reseeded for pre-VM usage, breaking reproducibility in tests like irq_test.
--

commit 62d9f92bdfe9d424d969de02ee382ed391548f81
Author: Sean Christopherson <seanjc@google.com>

KVM: selftests: Initialize the default/global pRNG during kvm_selftest_init()

This commit initializes the default kvm_rng during the selftest constructor 
so tests can use the pRNG before creating a VM. It also extracts the seeding 
logic into a new kvm_seed_rng() helper.

> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index 875030c22d07b..1016865d3f7a2 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -24,6 +24,13 @@ u32 kvm_random_seed;
>  struct kvm_random_state kvm_rng;
>  static u32 last_kvm_seed;
>  
> +static void kvm_seed_rng(u32 seed)
> +{
> +	kvm_random_seed = last_kvm_seed = seed;
> +	pr_info("Random seed: 0x%x\n", kvm_random_seed);
> +	kvm_rng = new_kvm_random_state(kvm_random_seed);
> +}
> +

[Severity: Medium]
Does making this function static prevent tests from reseeding the PRNG
early?

If a test draws from kvm_rng before __vm_create() is called (for example,
generating gsi and vector at the start of main() in irq_test), the test
will use the initial seed from the constructor.

Since kvm_seed_rng() is static and only automatically reseeded during
__vm_create(), how can developers override the seed to reproduce CI failures
for these pre-VM random variables?

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260626213534.3866178-1-seanjc@google.com?part=4