[PATCH 1/2] KVM: selftests: Fix nx_huge_pages_test for default_hugepagesz=1G

[Dongsheng Zhang <dongsheng.x.zhang@intel.com>]

From: donsheng <dongsheng.x.zhang@intel.com>

If the host was booted with the "default_hugepagesz=1G" kernel command-line
parameter, running the NX hugepage test will fail with error "Invalid argument"
at the TEST_ASSERT line in kvm_util.c's __vm_mem_region_delete() function:
static void __vm_mem_region_delete(struct kvm_vm *vm,
                   struct userspace_mem_region *region,
                   bool unlink)
{
    int ret;
    ...
    ret = munmap(region->mmap_start, region->mmap_size);
    TEST_ASSERT(!ret, __KVM_SYSCALL_ERROR("munmap()", ret));
    ...
}

NX hugepage test creates a VM with a data slot of 6M size backed with huge
pages. If the default hugetlb page size is set to 1G, calling mmap() with
MAP_HUGETLB and a length of 6M will succeed but calling its matching munmap()
will fail. Documentation/admin-guide/mm/hugetlbpage.rst specifies this behavior:

"Syscalls that operate on memory backed by hugetlb pages only have their lengths
aligned to the native page size of the processor; they will normally fail with
errno set to EINVAL or exclude hugetlb pages that extend beyond the length if
not hugepage aligned.  For example, munmap(2) will fail if memory is backed by
a hugetlb page and the length is smaller than the hugepage size."

Explicitly use MAP_HUGE_2MB in conjunction with MAP_HUGETLB to fix the issue.

Signed-off-by: donsheng <dongsheng.x.zhang@intel.com>
Suggested-by: Zide Chen <zide.chen@intel.com>
---
 tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
index 17bbb96fc4df..146e9033e206 100644
--- a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
+++ b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
@@ -129,7 +129,7 @@ void run_test(int reclaim_period_ms, bool disable_nx_huge_pages,
 
 	vcpu = vm_vcpu_add(vm, 0, guest_code);
 
-	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS_HUGETLB,
+	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS_HUGETLB_2MB,
 				    HPAGE_GPA, HPAGE_SLOT,
 				    HPAGE_SLOT_NPAGES, 0);
 
-- 
2.43.0