[PATCH 0/4] target/arm: Improvement on memory error handling

[Gavin Shan]

Currently, there is only one CPER buffer (entry), meaning only one
memory error can be reported. In extreme case, multiple memory errors
can be raised on different vCPUs. For example, a singile memory error
on a 64KB page of the host can results in 16 memory errors to 4KB
pages of the guest. Unfortunately, the virtual machine is simply aborted
by multiple concurrent memory errors, as the following call trace shows.
A SEA exception is injected to the guest so that the CPER buffer can
be claimed if the error is successfully pushed by acpi_ghes_memory_errors(),
Otherwise, abort() is triggered to crash the virtual machine.

  kvm_vcpu_thread_fn
    kvm_cpu_exec
      kvm_arch_on_sigbus_vcpu
        kvm_cpu_synchronize_state
        acpi_ghes_memory_errors         (a)
        kvm_inject_arm_sea | abort

It's arguably to crash the virtual machine in this case. The better
behaviour would be to retry on pushing the memory errors, to keep the
virtual machine alive so that the administrator has chance to chime
in, for example to dump the important data with luck. This series
adds one more parameter to acpi_ghes_memory_errors() so that it will
be tried to push the memory error until it succeeds.

Gavin Shan (4):
  acpi/ghes: Make ghes_record_cper_errors() static
  acpi/ghes: Use error_report() in ghes_record_cper_errors()
  acpi/ghes: Allow retry to write CPER errors
  target/arm: Retry pushing CPER error if necessary

 hw/acpi/ghes-stub.c    |  3 ++-
 hw/acpi/ghes.c         | 45 +++++++++++++++++++++---------------------
 include/hw/acpi/ghes.h |  5 ++---
 target/arm/kvm.c       | 31 +++++++++++++++++++++++------
 4 files changed, 51 insertions(+), 33 deletions(-)

-- 
2.48.1