Ubuntu
linux package

  1. Bug #1874055
  2. Comment #1

Comment 1 for bug 1874055

Revision history for this message
bugproxy (bugproxy) wrote : Comment bridged from LTC Bugzilla

------- Comment From <email address hidden> 2020-04-21 09:41 EDT-------
One of the PCI enhancements on Z15 are the enhanced PCI load/store instructions which can be executed directly from user space code. When these instructions are available and preexisting user space code still uses the old s390_pci_mmio_write/read system calls, the system calls fail with an "Unable to handle kernel pointer dereference in virtual kernel address space" in the kernel.

This issue affects distributions which have the enablement for Z15 PCI enhancements and where customers run workloads which accesses PCI adapters from user space, e.g. RDMA applications.

To solve this, the system call implementation needs to be enhanced to provide to execute enhanced PCI load/store instructions on behalf of the user space application making use of the mappings into its virtual address space