Re: [PATCH v6 09/18] KVM: arm64: Add selftests for the pKVM heap allocator

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] mm: leak of donated pages in hyp_allocator_selftest() error paths
--

commit e38e9008687b6871455e7ad734e5cd3158568487
Author: Vincent Donnefort <vdonnefort@google.com>

KVM: arm64: Add selftests for the pKVM heap allocator
    
Introduce a comprehensive runtime selftest for the pKVM hypervisor heap
allocator, executed during init when CONFIG_NVHE_EL2_DEBUG is enabled.
The selftest runs entirely at EL2 and exercises allocator core mechanisms
including allocation, chunk recycling, splitting, merging, and reclaiming.

> diff --git a/arch/arm64/kvm/hyp/nvhe/alloc.c b/arch/arm64/kvm/hyp/nvhe/alloc.c
> index e0104d2dd6c0e..c1881c0011c9e 100644
> --- a/arch/arm64/kvm/hyp/nvhe/alloc.c
> +++ b/arch/arm64/kvm/hyp/nvhe/alloc.c
[ ... ]
> @@ -1025,3 +1033,179 @@ u32 hyp_alloc_topup_needed(void)
[ ... ]
> +	/* Test reclaiming the last chunk of the list */
> +	selftest_free(addr4);
> +	hyp_allocator_reclaim(allocator, &host_mc, SELFTEST_MAX_PAGES);
> +	if (host_mc.nr_pages != SELFTEST_MAX_PAGES - 3)
> +		return -EINVAL;

[Severity: Medium]
Does this leak the reclaimed pages?

The allocator test reclaims pages into the local host_mc memcache.

If the assertion fails here (or in any of the subsequent checks before the
test completes), the function returns early without passing these pages back
to the host or freeing them.

This results in a permanent physical memory leak of up to 6 pages.

> +
> +	/* Test punching a hole in the middle of a free chunk ... */
> +	selftest_free(addr2);
> +	hyp_allocator_reclaim(allocator, &host_mc, SELFTEST_MAX_PAGES);
> +	if (host_mc.nr_pages != SELFTEST_MAX_PAGES - 2)
> +		return -EINVAL;
> +
> +	if (selftest_alloc(PAGE_SIZE))
> +		return -EINVAL;
> +	if (selftest_errno() != -ENOMEM)
> +		return -EINVAL;
> +
> +	/* ... and to refill this hole */
> +	ret = hyp_allocator_topup(allocator, &host_mc);
> +	if (ret)
> +		return ret;
[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261001142849.3367614-1-vdonnefort@google.com?part=9