Re: [PATCH v2 01/11] accel/kvm: Check MachineClass kvm_type() return value

[Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>]

On 2/22/21 6:24 PM, Cornelia Huck wrote:
> On Fri, 19 Feb 2021 18:38:37 +0100
> Philippe Mathieu-Daudé <philmd@xxxxxxxxxx> wrote:
> 
>> MachineClass::kvm_type() can return -1 on failure.
>> Document it, and add a check in kvm_init().
>>
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
>> ---
>>  include/hw/boards.h | 3 ++-
>>  accel/kvm/kvm-all.c | 6 ++++++
>>  2 files changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/hw/boards.h b/include/hw/boards.h
>> index a46dfe5d1a6..68d3d10f6b0 100644
>> --- a/include/hw/boards.h
>> +++ b/include/hw/boards.h
>> @@ -127,7 +127,8 @@ typedef struct {
>>   *    implement and a stub device is required.
>>   * @kvm_type:
>>   *    Return the type of KVM corresponding to the kvm-type string option or
>> - *    computed based on other criteria such as the host kernel capabilities.
>> + *    computed based on other criteria such as the host kernel capabilities
>> + *    (which can't be negative), or -1 on error.
>>   * @numa_mem_supported:
>>   *    true if '--numa node.mem' option is supported and false otherwise
>>   * @smp_parse:
>> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
>> index 84c943fcdb2..b069938d881 100644
>> --- a/accel/kvm/kvm-all.c
>> +++ b/accel/kvm/kvm-all.c
>> @@ -2057,6 +2057,12 @@ static int kvm_init(MachineState *ms)
>>                                                              "kvm-type",
>>                                                              &error_abort);
>>          type = mc->kvm_type(ms, kvm_type);
>> +        if (type < 0) {
>> +            ret = -EINVAL;
>> +            fprintf(stderr, "Failed to detect kvm-type for machine '%s'\n",
>> +                    mc->name);
>> +            goto err;
>> +        }
>>      }
>>  
>>      do {
> 
> No objection to this patch; but I'm wondering why some non-pseries
> machines implement the kvm_type callback, when I see the kvm-type
> property only for pseries? Am I holding my git grep wrong?

Can it be what David commented here?
https://www.mail-archive.com/qemu-devel@xxxxxxxxxx/msg784508.html