[PATCH 1/3] KVM: riscv: Pass the target size to huge G-stage checks

[Nutty.Liu]

On 5/20/2026 11:21 PM, Jinyu Tang wrote:
> fault_supports_gstage_huge_mapping() already contains the two checks
> needed before installing a G-stage block mapping: the userspace address
> and GPA must have matching offsets within the block, and the whole block
> must be contained within the memslot.
>
> The helper currently hard-codes PMD_SIZE because its only caller is the
> transparent hugepage path. The hugetlb path needs the same checks, but
> the target block size can be either PMD_SIZE or PUD_SIZE depending on the
> hugetlb VMA.
>
> So pass the target mapping size into the helper and use it for the
> alignment and bounds checks. This keeps the existing THP PMD behavior
> unchanged and prepares the helper to be reused for the following hugetlb
> fix.
>
> Signed-off-by: Jinyu Tang <tjytimi at 163.com>
> ---
>   arch/riscv/kvm/mmu.c | 14 ++++++++------
>   1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> index 2d3def024..10be8f683 100644
> --- a/arch/riscv/kvm/mmu.c
> +++ b/arch/riscv/kvm/mmu.c
> @@ -286,7 +286,8 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
>   }
>   
>   static bool fault_supports_gstage_huge_mapping(struct kvm_memory_slot *memslot,
> -					       unsigned long hva)
> +					       unsigned long hva,
> +					       unsigned long map_size)
>   {
>   	hva_t uaddr_start, uaddr_end;
>   	gpa_t gpa_start;
> @@ -300,8 +301,8 @@ static bool fault_supports_gstage_huge_mapping(struct kvm_memory_slot *memslot,
>   
>   	/*
>   	 * Pages belonging to memslots that don't have the same alignment
> -	 * within a PMD for userspace and GPA cannot be mapped with g-stage
> -	 * PMD entries, because we'll end up mapping the wrong pages.
> +	 * within a huge page for userspace and GPA cannot be mapped with
> +	 * g-stage block entries, because we'll end up mapping the wrong pages.
>   	 *
>   	 * Consider a layout like the following:
>   	 *
> @@ -321,7 +322,7 @@ static bool fault_supports_gstage_huge_mapping(struct kvm_memory_slot *memslot,
>   	 *   e -> g
>   	 *   f -> h
>   	 */
> -	if ((gpa_start & (PMD_SIZE - 1)) != (uaddr_start & (PMD_SIZE - 1)))
> +	if ((gpa_start & (map_size - 1)) != (uaddr_start & (map_size - 1)))
>   		return false;
>   
>   	/*
> @@ -336,7 +337,8 @@ static bool fault_supports_gstage_huge_mapping(struct kvm_memory_slot *memslot,
>   	 * userspace_addr or the base_gfn, as both are equally aligned (per
>   	 * the check above) and equally sized.
>   	 */
> -	return (hva >= ALIGN(uaddr_start, PMD_SIZE)) && (hva < ALIGN_DOWN(uaddr_end, PMD_SIZE));
> +	return (hva & ~(map_size - 1)) >= uaddr_start &&
> +	       (hva & ~(map_size - 1)) + map_size <= uaddr_end;
Seems they are not exactly the same.
Should be like this ?

+	return (hva >= ALIGN(uaddr_start, map_size)) && (hva < ALIGN_DOWN(uaddr_end, map_size));

Otherwise,
Reviewed-by: Nutty Liu <nutty.liu at hotmail.com>

Thanks,
Nutty
>   }
>   
>   static int get_hva_mapping_size(struct kvm *kvm,
> @@ -404,7 +406,7 @@ static unsigned long transparent_hugepage_adjust(struct kvm *kvm,
>   	 * sure that the HVA and GPA are sufficiently aligned and that the
>   	 * block map is contained within the memslot.
>   	 */
> -	if (fault_supports_gstage_huge_mapping(memslot, hva)) {
> +	if (fault_supports_gstage_huge_mapping(memslot, hva, PMD_SIZE)) {
>   		int sz;
>   
>   		sz = get_hva_mapping_size(kvm, hva);