[PATCH v17 23/24] KVM: selftests: guest_memfd mmap() test when mmap is supported

[Shivank Garg]

On 7/30/2025 4:24 AM, Sean Christopherson wrote:
> From: Fuad Tabba <tabba at google.com>
> 
> Expand the guest_memfd selftests to comprehensively test host userspace
> mmap functionality for guest_memfd-backed memory when supported by the
> VM type.
> 
> Introduce new test cases to verify the following:
> 
> * Successful mmap operations: Ensure that MAP_SHARED mappings succeed
>   when guest_memfd mmap is enabled.
> 
> * Data integrity: Validate that data written to the mmap'd region is
>   correctly persistent and readable.
> 
> * fallocate interaction: Test that fallocate(FALLOC_FL_PUNCH_HOLE)
>   correctly zeros out mapped pages.
> 
> * Out-of-bounds access: Verify that accessing memory beyond the
>   guest_memfd's size correctly triggers a SIGBUS signal.
> 
> * Unsupported mmap: Confirm that mmap attempts fail as expected when
>   guest_memfd mmap support is not enabled for the specific guest_memfd
>   instance or VM type.
> 
> * Flag validity: Introduce test_vm_type_gmem_flag_validity() to
>   systematically test that only allowed guest_memfd creation flags are
>   accepted for different VM types (e.g., GUEST_MEMFD_FLAG_MMAP for
>   default VMs, no flags for CoCo VMs).
> 
> The existing tests for guest_memfd creation (multiple instances, invalid
> sizes), file read/write, file size, and invalid punch hole operations
> are integrated into the new test_with_type() framework to allow testing
> across different VM types.
> 
> Cc: James Houghton <jthoughton at google.com>
> Cc: Gavin Shan <gshan at redhat.com>
> Cc: Shivank Garg <shivankg at amd.com>
> Co-developed-by: Ackerley Tng <ackerleytng at google.com>
> Signed-off-by: Ackerley Tng <ackerleytng at google.com>
> Signed-off-by: Fuad Tabba <tabba at google.com>
> Co-developed-by: Sean Christopherson <seanjc at google.com>
> Signed-off-by: Sean Christopherson <seanjc at google.com>
> ---
>  .../testing/selftests/kvm/guest_memfd_test.c  | 161 +++++++++++++++---
>  1 file changed, 139 insertions(+), 22 deletions(-)
> 

Reviewed-by: Shivank Garg <shivankg at amd.com>