Re: [PATCH v2 3/5] KVM: riscv: selftests: Fix incorrect rounding in page_align()

Andrew Jones
2025-12-22T18:07:18Z

On Mon, Dec 15, 2025 at 04:51:53PM +0000, Fuad Tabba wrote:
> The implementation of `page_align()` in `processor.c` calculates
> alignment incorrectly for values that are already aligned. Specifically,
> `(v + vm->page_size) & ~(vm->page_size - 1)` aligns to the *next* page
> boundary even if `v` is already page-aligned, potentially wasting a page
> of memory.
>
> Fix the calculation to use standard alignment logic: `(v + vm->page_size
> - 1) & ~(vm->page_size - 1)`.
>
> Fixes: 3e06cdf10520 ("KVM: selftests: Add initial support for RISC-V 64-bit")
> Signed-off-by: Fuad Tabba <tabba@google.com>
> ---
> tools/testing/selftests/kvm/lib/riscv/processor.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/kvm/lib/riscv/processor.c b/tools/testing/selftests/kvm/lib/riscv/processor.c
> index 2eac7d4b59e9..d5e8747b5e69 100644
> --- a/tools/testing/selftests/kvm/lib/riscv/processor.c
> +++ b/tools/testing/selftests/kvm/lib/riscv/processor.c
> @@ -28,7 +28,7 @@ bool __vcpu_has_ext(struct kvm_vcpu *vcpu, uint64_t ext)
>
> static uint64_t page_align(struct kvm_vm *vm, uint64_t v)
> {
> - return (v + vm->page_size) & ~(vm->page_size - 1);
> + return (v + vm->page_size - 1) & ~(vm->page_size - 1);
> }
>
> static uint64_t pte_addr(struct kvm_vm *vm, uint64_t entry)
> --
> 2.52.0.239.gd5f0c6e74e-goog

Reviewed-by: Andrew Jones <andrew.jones@linux.dev>