On 2/22/21 6:50 PM, Cornelia Huck wrote:
> On Mon, 22 Feb 2021 18:41:07 +0100
> Philippe Mathieu-Daudé <philmd@xxxxxxxxxx> wrote:
>
>> 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
>>
>
> Ok, I might be confused about the other ppc machines; but I'm wondering
> about the kvm_type callback for mips and arm/virt. Maybe I'm just
> confused by the whole mechanism?
For MIPS see https://www.linux-kvm.org/images/f/f2/01x08a-MIPS.pdf
and Jiaxun comment here:
https://lore.kernel.org/linux-mips/a2a2cfe3-5618-43b1-a6a4-cc768fc1b9fb@xxxxxxxxxxxxxxxx/
TE KVM: Trap-and-Emul guest kernel
VZ KVM: HW Virtualized
For "the whole mechanism" I'll defer to Paolo =)
