[PATCH v9 0/2] Use DIAG318 to set Control Program Name & Version Codes

Collin Walling
2020-06-22T15:46:52Z

Changelog:

v9

• No longer unshadowing CPNC in VSIE

v8

• Reset is handled in KVM during initial and clear resets
• Sync/Store register handling
• Removed device IOCTL code
• Added KVM Capability for DIAG318
- this is for determining if the CPU model can enable this feature
• Reverted changes introduced by bullet 3 in v7
• Unshadowing CPNC again, as it makes sense if the guest executing in
VSIE sets a unique name/version code; this data should be preserved
- reverts bullet 4 in v3 [removed in v9]
• Diag318 is no longer reported via VM or CPU events
- no place to put this such that the messages aren't flooding the logs
- not necessary, as this data is primarily for IBM hardware/firmware
service events, and is observable via such events (e.g. CPU ring
dump)
- was nice for testing purposes
• A copy of the diag318 info (name & version code) is now stored in
the kvm_vcpu_arch struct, as opposed to the kvm_arch struct

v7

• Removed diag handler, as it will now take place within userspace
• Removed KVM_S390_VM_MISC_ENABLE_DIAG318 (undoes first bullet in v6)
• Misc clean ups and fixes [removed in v8]
- introduced a new patch to s/diag318/diag_318 and s/byte_134/fac134
to keep things consistent with the rest of the code

v6

• KVM disables diag318 get/set by default [removed in v7]
• added new IOCTL to tell KVM to enable diag318 [removed in v7]
• removed VCPU event message in favor of VM_EVENT only [removed in v8]

v5

• s/cpc/diag318_info in order to make the relevant data more clear
• removed mutex locks for diag318_info get/set

v4

• removed setup.c changes introduced in bullet 1 of v3
• kept diag318_info struct cleanup
• analogous QEMU patches:
https://lists.gnu.org/archive/html/qemu-devel/2019-05/msg00164.html

v3

• kernel patch for diag 0x318 instruction call fixup [removed in v4]
• removed CPU model code
• cleaned up diag318_info struct
• cpnc is no longer unshadowed as it was not needed [removed in v8]
• rebased on 5.1.0-rc3

-------------------------------------------------------------------------------

This instruction call is executed once-and-only-once during Kernel setup.
The availability of this instruction depends on Read Info byte 134 (aka fac134),
bit 0.

DIAG 0x318's is handled by userspace and may be enabled for a guest even if the
host kernel cannot support it.

The diag318_info is composed of a Control Program Name Code (CPNC) and a
Control Program Version Code (CPVC). The CPNC is stored in the SIE block, and
the CPNC & CPVC pair is stored in the kvm_vcpu_arch struct.

These values are used for problem diagnosis and allows IBM to identify control
program information by answering the following question:

"What environment is this guest running in?" (CPNC)
"What are more details regarding the OS?" (CPVC)

In the future, we will implement the CPVC to convey more information about the
OS (such as Linux version and potentially some value denoting a specific
distro + release). For now, we set this field to 0 until we come up with a solid
plan.

Collin Walling (2):
s390/setup: diag 318: refactor struct
s390/kvm: diagnose 0x318 sync and reset

arch/s390/include/asm/diag.h | 6 ++----
arch/s390/include/asm/kvm_host.h | 4 +++-
arch/s390/include/uapi/asm/kvm.h | 5 ++++-
arch/s390/kernel/setup.c | 3 +--
arch/s390/kvm/kvm-s390.c | 11 ++++++++++-
arch/s390/kvm/vsie.c | 1 +
include/uapi/linux/kvm.h | 1 +
7 files changed, 22 insertions(+), 9 deletions(-)

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2.26.2