[v7] Mitigation of "failed to load cpu:cpreg_vmstate_array_len" migration failures

[PATCH v7 0/7] Mitigation of "failed to load cpu:cpreg_vmstate_array_len" migration failures

Eric Auger posted 7 patches 1 month, 1 week ago

Diff against v1 v1 v2 v3 v4 v5 v6 v8 v9
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target/arm/cpu.h          | 32 +++++++++++++++++
target/arm/cpu.c          | 75 +++++++++++++++++++++++++++++++++++++++
target/arm/cpu64.c        | 34 ++++++++++++++++++
target/arm/debug_helper.c | 29 ---------------
target/arm/helper.c       |  5 +++
target/arm/machine.c      | 70 +++++++++++++++++++++++++++++-------
target/arm/trace-events   |  2 ++
7 files changed, 206 insertions(+), 41 deletions(-)

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[PATCH v7 0/7] Mitigation of "failed to load cpu:cpreg_vmstate_array_len" migration failures

Posted by Eric Auger 1 month, 1 week ago

This series applies on top of
[PATCH 0/5] Improve traces on migration failure due to cpreg number mismatch
https://lore.kernel.org/all/20260226100232.500781-1-eric.auger@redhat.com/

It introduces an infrastructure to explicitly tolerate some
mismatches between cpu cpreg indexes/values on migration.

We especially handle failures due to an attempt to migrate
more registers than exposed on the destination.

Once the infrastructure is in place we can handle the following
known issues:
KVM:
- removal of unconditionnal exposure of TCR2_EL1, PIRE0_EL1, PIR_EL1
  from v6.13 onwards. Causes forward migration failure.
- unconditionnal exposure of KVM_REG_ARM_VENDOR_HYP_BMAP_2 FW pseudo
  register from v6.16 onwards. Causes backward migration failure.
TCG:
- We can eventually remove AArch32 DBGDTRTX register which was
  erroneously defined.

Both series are available at:
https://github.com/eauger/qemu/tree/cpreg_vmstate_array_len_traces_mitig

History:
v6 -> v7
- complete rework after Peter's comments in
  (https://lore.kernel.org/all/20260126165445.3033335-1-eric.auger@redhat.com/)
  Especially it does not use properties at all. Do not feature hidden regs
  Also the initial series was split into 2.

Eric Auger (7):
  target/arm/machine: Fix detection of unknown incoming cpregs
  target/arm/cpu: Introduce the infrastructure for cpreg migration
    tolerances
  target/arm/machine: Take account cpreg mig tolerances in case of
    mismatch
  target/arm/cpu64: Mitigate migration failures due to spurious TCR_EL1,
    PIRE0_EL1 and PIR_EL1
  target/arm/cpu64: Define cpreg migration tolerance for
    KVM_REG_ARM_VENDOR_HYP_BMAP_2
  target/arm/helper: Define cpreg migration tolerance for DGBDTR_EL0
  Revert "target/arm: Reinstate bogus AArch32 DBGDTRTX register for
    migration compat"

 target/arm/cpu.h          | 32 +++++++++++++++++
 target/arm/cpu.c          | 75 +++++++++++++++++++++++++++++++++++++++
 target/arm/cpu64.c        | 34 ++++++++++++++++++
 target/arm/debug_helper.c | 29 ---------------
 target/arm/helper.c       |  5 +++
 target/arm/machine.c      | 70 +++++++++++++++++++++++++++++-------
 target/arm/trace-events   |  2 ++
 7 files changed, 206 insertions(+), 41 deletions(-)

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2.53.0