Re: [PATCH] powerpc: increase MIN RMA size for CAS negotiation

[Avnish Chouhan <avnish@linux.ibm.com>]

On 2025-02-06 13:00, Michael Chang wrote:
> On Wed, Jan 15, 2025 at 05:46:05PM +0530, Avnish Chouhan wrote:
>> Change RMA size from 512 MB to 768 MB which will result
>> in more memory at boot time for PowerPC. When PowerPC LPAR use/uses 
>> vTPM,
>> Secure Boot or FADump, the 512 MB RMA memory is not sufficient for
>> booting. With this 512 MB RMA, GRUB2 run out of memory and unable to
>> load the necessary. Sometimes even usage of CDROM which requires more
>> memory for installation along with the options mentioned above 
>> troubles
>> the boot memory and result in boot failures. Increasing the RMA size
>> will resolves multiple out of memory issues observed in PowerPC.
> 
> How often does the CAS reboot to claim additional RMA memory? Does this
> occur only once, or during every cold boot/reboot?
> 
> I hope it happens only once, because doing it repeatedly could
> complicate the configuration of the TPM PCR policy.
> 
> Thanks,
> Michael
> 

Hi Michael,

The CAS call to claim additional RMA memory will happen only once.
Thank you!

Regards,
Avnish Chouhan

>> 
>> Failure details (GRUB2 debugs):
>> 
>> kern/ieee1275/init.c:550: mm requested region of size 8513000, flags 1
>> kern/ieee1275/init.c:563: Cannot satisfy allocation and retain minimum 
>> runtime
>> space
>> kern/ieee1275/init.c:550: mm requested region of size 8513000, flags 0
>> kern/ieee1275/init.c:563: Cannot satisfy allocation and retain minimum 
>> runtime
>> space
>> kern/file.c:215: Closing `/ppc/ppc64/initrd.img' ...
>> kern/disk.c:297: Closing
>> `ieee1275//vdevice/v-scsi
>> @30000067/disk@8300000000000000'...
>> kern/disk.c:311: Closing
>> `ieee1275//vdevice/v-scsi
>> @30000067/disk@8300000000000000' succeeded.
>> kern/file.c:225: Closing `/ppc/ppc64/initrd.img' failed with 3.
>> kern/file.c:148: Opening `/ppc/ppc64/initrd.img' succeeded.
>> error: ../../grub-core/kern/mm.c:552:out of memory.
>> 
>> Signed-off-by: Avnish Chouhan <avnish@linux.ibm.com>
>> ---
>>  grub-core/kern/ieee1275/init.c | 33 +++++++++++++++++++++++++++++----
>>  1 file changed, 29 insertions(+), 4 deletions(-)
>> 
>> diff --git a/grub-core/kern/ieee1275/init.c 
>> b/grub-core/kern/ieee1275/init.c
>> index dfbd0b8..502ebf1 100644
>> --- a/grub-core/kern/ieee1275/init.c
>> +++ b/grub-core/kern/ieee1275/init.c
>> @@ -852,7 +852,7 @@ grub_ieee1275_ibm_cas (void)
>>      .vec1 = 0x80, /* ignore */
>>      .vec2_size = 1 + sizeof (struct option_vector2) - 2,
>>      .vec2 = {
>> -      0, 0, -1, -1, -1, -1, -1, 512, -1, 0, 48
>> +      0, 0, -1, -1, -1, -1, -1, 768, -1, 0, 48
>>      },
>>      .vec3_size = 2 - 1,
>>      .vec3 = 0x00e0, /* ask for FP + VMX + DFP but don't halt if 
>> unsatisfied */
>> @@ -889,6 +889,10 @@ grub_claim_heap (void)
>>  {
>>    grub_err_t err;
>>    grub_uint32_t total = HEAP_MAX_SIZE;
>> +#if defined(__powerpc__)
>> +  grub_uint32_t ibm_ca_support_reboot;
>> +  grub_ssize_t actual;
>> +#endif
>> 
>>    err = grub_ieee1275_total_mem (&rmo_top);
>> 
>> @@ -901,11 +905,32 @@ grub_claim_heap (void)
>>      grub_mm_add_region_fn = grub_ieee1275_mm_add_region;
>> 
>>  #if defined(__powerpc__)
>> +  /* Check if it's a CAS reboot with below property. If so, we will 
>> skip CAS call */
>> +  ibm_ca_support_reboot = 0;
>> +  if (grub_ieee1275_get_integer_property (grub_ieee1275_chosen,
>> +                                          
>> "ibm,client-architecture-support-reboot",
>> +                                          &ibm_ca_support_reboot,
>> +                                          sizeof 
>> (ibm_ca_support_reboot),
>> +                                          &actual) >= 0)
>> +    grub_dprintf ("ieee1275", 
>> "ibm,client-architecture-support-reboot: %u\n",
>> +                  ibm_ca_support_reboot);
>> +
>>    if (grub_ieee1275_test_flag 
>> (GRUB_IEEE1275_FLAG_CAN_TRY_CAS_FOR_MORE_MEMORY))
>>      {
>> -      /* if we have an error, don't call CAS, just hope for the best 
>> */
>> -      if (err == GRUB_ERR_NONE && rmo_top < (512 * 1024 * 1024))
>> -	grub_ieee1275_ibm_cas ();
>> +      /*
>> +       * If we have an error or the reboot is detected as CAS reboot,
>> +       * don't call CAS, just hope for the best.
>> +       * Along with the above, if the rmo_top is 512 MB or above. We
>> +       * will skip the CAS call. Though if we call CAS, the rmo_top 
>> will
>> +       * be set to 768 MB via CAS Vector2. This condition is required 
>> to avoid the
>> +       * issue where the older Linux kernels are still using rmo_top 
>> as 512 MB.
>> +       * Calling CAS when rmo_top is less then 768 MB will result in 
>> a issue
>> +       * where we won't be able to boot to a newer kernel and 
>> continue to
>> +       * boot with older kernel having rmo_top as 512 MB.
>> +       */
>> +      if (!ibm_ca_support_reboot && err == GRUB_ERR_NONE
>> +          && rmo_top < (512 * 1024 * 1024))
>> +        grub_ieee1275_ibm_cas ();
>>      }
>>  #endif
>> 
>> --
>> 2.39.3
>> 
>> 
>> _______________________________________________
>> Grub-devel mailing list
>> Grub-devel@gnu.org
>> https://lists.gnu.org/mailman/listinfo/grub-devel

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