** Changed in: ubuntu-z-systems
Assignee: (unassigned) => Skipper Bug Screeners (skipper-screen-team)
** Changed in: linux (Ubuntu)
Status: New => Incomplete
** Changed in: linux (Ubuntu)
Assignee: Skipper Bug Screeners (skipper-screen-team) => Canonical Kernel
Team (canonical-kernel-team)
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https://bugs.launchpad.net/bugs/1874055
Title:
[UBUNTU 20.04] s390x/pci: s390_pci_mmio_write/read fail when MIO
instructions are available
Status in Ubuntu on IBM z Systems:
Incomplete
Status in linux package in Ubuntu:
Incomplete
Bug description:
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
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