x86/sgx: Break up long non-preemptible delays in sgx_vepc_release()

On large enclaves we hit the softlockup warning with following call trace:

	xa_erase()
	sgx_vepc_release()
	__fput()
	task_work_run()
	do_exit()

The latency issue is similar to the one fixed in:

  8795359e35bc ("x86/sgx: Silence softlockup detection when releasing large enclaves")

The test system has 64GB of enclave memory, and all is assigned to a single VM.
Release of 'vepc' takes a longer time and causes long latencies, which triggers
the softlockup warning.

Add cond_resched() to give other tasks a chance to run and reduce
latencies, which also avoids the softlockup detector.

[ mingo: Rewrote the changelog. ]

Fixes: 540745ddbc70 ("x86/sgx: Introduce virtual EPC for use by KVM guests")
Reported-by: Yu Zhang <[email protected]>
Signed-off-by: Jack Wang <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Tested-by: Yu Zhang <[email protected]>
Reviewed-by: Jarkko Sakkinen <[email protected]>
Reviewed-by: Kai Huang <[email protected]>
Acked-by: Haitao Huang <[email protected]>
Cc: [email protected]

0 files changed, 0 insertions, 0 deletions