Re: [PULL 9/9] hw/i386: pass RNG seed via setup_data entry

[Xiaoyao Li <xiaoyao.li@intel.com>]

On 8/2/2022 9:21 PM, Jason A. Donenfeld wrote:
> Hi,
> 
> On Tue, Aug 02, 2022 at 11:28:15AM +0800, Xiaoyao Li wrote:
>>>    static void pc_q35_7_0_machine_options(MachineClass *m)
>>>    {
>>> +    PCMachineClass *pcmc = PC_MACHINE_CLASS(m);
>>>        pc_q35_7_1_machine_options(m);
>>>        m->alias = NULL;
>>> +    pcmc->legacy_no_rng_seed = true;
>>
>> Is making .legacy_no_rng_seed default false and opt-in it for old
>> machines correct?
> 
> Not sure I follow what you're saying. ≤7.0 won't pass the RNG seed. It's
> only on ≥7.1 that the RNG seed is used.

yes, with >= 7.1, pcmc->legacy_no_rng_seed = false by default, and RNG 
seed is used.

> Either way, this shouldn't cause boot failures.

It does fail booting OVMF with #PF. Below diff can fix the #PF for me.

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 7280c02ce3d5..1f62971759bf 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1903,6 +1903,7 @@ static void pc_machine_class_init(ObjectClass *oc, 
void *data)
      pcmc->has_reserved_memory = true;
      pcmc->kvmclock_enabled = true;
      pcmc->enforce_aligned_dimm = true;
+    pcmc->legacy_no_rng_seed = true;
      pcmc->enforce_amd_1tb_hole = true;
      /* BIOS ACPI tables: 128K. Other BIOS datastructures: less than 4K 
reported
       * to be used at the moment, 32K should be enough for a while.  */

> Jason