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

[Gavin Shan <gshan@redhat.com>]

On 2/14/25 7:53 PM, Jonathan Cameron wrote:
> On Fri, 14 Feb 2025 14:16:31 +1000
> Gavin Shan <gshan@redhat.com> wrote:
> 
>> 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.
> 
> Hi Gavin,
> 
> +CC Mauro given:
> https://lore.kernel.org/all/cover.1738345063.git.mchehab+huawei@kernel.org/
> 
> is more or less reviewed subject to some requested patch reordering and
> whilst I haven't checked, seems unlikely that there won't be a
> clash with this series (might just be some fuzz)
> 

Jonathan, thanks for the pointer. I didn't notice there are pending acpi/hest
changes. The changes clash with those included in this series, I will take a
close look.

Thanks,
Gavin

> Jonathan
> 
> 
> 
>>
>> 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(-)
>>
>