Re: [kvm-unit-tests PATCH] powerpc: Fix running the kvm-unit-tests with recent versions of QEMU

On 06/12/2022 11.40, Cédric Le Goater wrote:
> On 12/6/22 11:14, Thomas Huth wrote:
>> Starting with version 7.0, QEMU starts the pseries guests in 32-bit mode
>> instead of 64-bit (see QEMU commit 6e3f09c28a - "spapr: Force 32bit when
>> resetting a core"). This causes our test_64bit() in powerpc/emulator.c
>> to fail. Let's switch to 64-bit in our startup code instead to fix the
>> issue.
>>
>> Signed-off-by: Thomas Huth <[email protected]>
>> ---
>>   powerpc/cstart64.S | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/powerpc/cstart64.S b/powerpc/cstart64.S
>> index 972851f9..206c518f 100644
>> --- a/powerpc/cstart64.S
>> +++ b/powerpc/cstart64.S
>> @@ -23,6 +23,12 @@
>>   .globl start
>>   start:
>>       FIXUP_ENDIAN
>> +    /* Switch to 64-bit mode */
>> +    mfmsr    r1
>> +    li    r2,1
>> +    sldi    r2,r2,63
>> +    or    r1,r1,r2
>> +    mtmsrd    r1
>>       /*
>>        * We were loaded at QEMU's kernel load address, but we're not
>>        * allowed to link there due to how QEMU deals with linker VMAs,
> 
> You could add this define in lib/powerpc/asm/ppc_asm.h  :
> 
> #define MSR_SF    0x8000000000000000ul
> 
> and possibly use the LOAD_REG_IMMEDIATE macro to set the MSR.

Using LOAD_REG_IMMEDIATE would add quite a bit of additional instructions 
here, so not sure whether I like it ... but I think I could add a proper 
#define for 63 at least.

  Thomas