Re: [PATCH 1/2] KVM: selftest: arm64: Support 5-level paging in stage 1 translation table

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The page table dump function `pte_dump()` is missing the 'p4d' string for 5-level paging.
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commit a04aa92b1663291806024b3dd2c32f253a43baf3
Author: Itaru Kitayama <itaru.kitayama@fujitsu.com>

KVM: selftest: arm64: Support 5-level paging in stage 1 translation table

Add p4d_index() for when 5-level paging required, i.e., V52 guest mode
IDs. With the index helper function, _virt_pg_map() handles 5-level
paging case, and aarch64_vcpu_setup() now is aware of the new V52 guest
mode IDs.

> diff --git a/tools/testing/selftests/kvm/lib/arm64/processor.c b/tools/testing/selftests/kvm/lib/arm64/processor.c
> index 01325bf4d36fc..9108e14a9b5be 100644
> --- a/tools/testing/selftests/kvm/lib/arm64/processor.c
> +++ b/tools/testing/selftests/kvm/lib/arm64/processor.c
[ ... ]
> @@ -182,18 +200,35 @@ void virt_arch_pg_map(struct kvm_vm *vm, gva_t gva, gpa_t gpa)
>  
>  u64 *virt_get_pte_hva_at_level(struct kvm_vm *vm, gva_t gva, int level)
>  {
> +	int start_level = 4 - vm->mmu.pgtable_levels;
>  	u64 *ptep;
>  
> +	TEST_ASSERT(level >= start_level && level <= 3,
> +		    "Invalid translation level %d, valid range is %d-3",
> +		    level, start_level);
> +
>  	if (!vm->mmu.pgd_created)
>  		goto unmapped_gva;
>  
>  	ptep = addr_gpa2hva(vm, vm->mmu.pgd) + pgd_index(vm, gva) * 8;
>  	if (!ptep)
>  		goto unmapped_gva;
> -	if (level == 0)
> +	/*
> +	 * Stage-1 translation starts at level -1 for a five-level page
> +	 * table, and at levels 0, 1, or 2 for four-, three-, or two-level
> +	 * page tables, respectively.
> +	 */
> +	if (level == start_level)
>  		return ptep;
>  
>  	switch (vm->mmu.pgtable_levels) {
> +	case 5:
> +		ptep = addr_gpa2hva(vm, pte_addr(vm, *ptep)) + p4d_index(vm, gva) * 8;
> +		if (!ptep)
> +			goto unmapped_gva;
> +		if (level == 0)
> +			break;
> +		/* fall through */
>  	case 4:

[Severity: Low]
Does pte_dump() also need to be updated to handle the new p4d level?

In tools/testing/selftests/kvm/lib/arm64/processor.c:pte_dump():

	static const char * const type[] = { "", "pud", "pmd", "pte" };

With 5-level paging enabled, virt_arch_dump() starts with level 0. The
pte_dump() function will access index 0 and print an empty string instead
of "p4d".

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Sashiko AI review · https://sashiko.dev/#/patchset/20260826-arm64-52bit-va-v1-0-14ec98211363@fujitsu.com?part=1