KVM: arm64: selftests: Fix EINJ handling in sea_to_user

sea_to_user drives EINJ injection through popen("echo ... > file"). A
failed write is hidden behind the shell pipeline, so a botched injection
is silently ignored and the test proceeds as if a poison were placed.
Drive the debugfs interface directly so a write failure is reported
rather than swallowed.

The EINJ support probe is also unreliable. It checks the ACPI EINJ table
with access(R_OK), but reading that table needs CAP_SYS_ADMIN, so the
check gives a false negative for unprivileged runs and skips a test that
could otherwise report a real problem. Probe by opening the debugfs
injection interface instead and classify errno: absence means EINJ is
not built or firmware lacks support, EACCES/EPERM means the test is not
running as root -- both are skips -- while anything else is a genuine
failure.

The injection path is only reachable through debugfs; the kernel EINJ
driver exposes no other interface, so the test must depend on it.

Link: https://lore.kernel.org/kvm/86y0le9cvz.wl-maz@kernel.org/
Signed-off-by: Like Xu <likexu@tencent.com>
Link: https://patch.msgid.link/20260818112920.26252-2-likexu@tencent.com
Signed-off-by: Marc Zyngier <maz@kernel.org>

0 files changed, 0 insertions, 0 deletions