KVM: riscv: selftests: Fix incorrect rounding in page_align()

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")
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20260109082218.3236580-4-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/tools/testing/selftests/kvm/lib/riscv/processor.c b/tools/testing/selftests/kvm/lib/riscv/processor.c
index 2eac7d4b59e90142082f69b235d48d1f8b5fd7fc..d5e8747b5e69b7e45558506d7c4082d6d1fd28ec 100644 (file)
--- 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)