Hi Andre,
On 6/10/21 5:13 PM, Andre Przywara wrote:
> On Wed, 9 Jun 2021 19:38:10 +0100
> Alexandru Elisei <alexandru.elisei@xxxxxxx> wrote:
>
>> Print a more helpful warning when a MMIO device hasn't set a function to
>> generate an FDT instead of causing a segmentation fault by dereferencing a
>> NULL pointer.
> Not calling generate_mmio_fdt_nodes() if it's NULL is certainly a good
> idea, but how did you trigger it?
I was able to trigger it when I was hacking a custom MMIO device emulation to test
some behaviour in KVM.
> Because I am wondering whether every MMIO device needs to have an DT
> generator? And if that's not the case, a warning might be already too
> much.
I don't know how the guest will be able to discover the device if it's not in the
DT, that's why I put the warning. If there are devices which can be discovered by
the guest when they are missing from the DT, then I'll drop the warning.
Thanks,
Alex
>
> So either just drop a print at all or use pr_info()/pr_debug()?
>
> Cheers,
> Andre
>
>> Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
>> ---
>> arm/fdt.c | 7 ++++++-
>> 1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/arm/fdt.c b/arm/fdt.c
>> index 02091e9e0bee..06287a13e395 100644
>> --- a/arm/fdt.c
>> +++ b/arm/fdt.c
>> @@ -171,7 +171,12 @@ static int setup_fdt(struct kvm *kvm)
>> dev_hdr = device__first_dev(DEVICE_BUS_MMIO);
>> while (dev_hdr) {
>> generate_mmio_fdt_nodes = dev_hdr->data;
>> - generate_mmio_fdt_nodes(fdt, dev_hdr, generate_irq_prop);
>> + if (generate_mmio_fdt_nodes) {
>> + generate_mmio_fdt_nodes(fdt, dev_hdr, generate_irq_prop);
>> + } else {
>> + pr_warning("Missing FDT node generator for MMIO device %d",
>> + dev_hdr->dev_num);
>> + }
>> dev_hdr = device__next_dev(dev_hdr);
>> }
>>
