Re: [Qemu-devel] [Qemu-ppc] [PULL 04/12] ppc: tlbie, tlbia and tlbisync are HV only

[Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>]

On 02/06/16 09:47, Mark Cave-Ayland wrote:

> On 02/06/16 09:23, Cédric Le Goater wrote:
> 
>> On 06/02/2016 09:45 AM, Mark Cave-Ayland wrote:
>>> On 02/06/16 08:37, Cédric Le Goater wrote:
>>>> On 06/02/2016 05:17 AM, David Gibson wrote:
>>>>> On Wed, Jun 01, 2016 at 08:03:08AM +0100, Mark Cave-Ayland wrote:
>>>>>> On 01/06/16 03:15, David Gibson wrote:
>>>>>>
>>>>>>> On Tue, May 31, 2016 at 11:28:49PM +0100, Mark Cave-Ayland wrote:
>>>>>>>> On 31/05/16 01:41, David Gibson wrote:
>>>>>>>>
>>>>>>>>> From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>>>>>>>>>
>>>>>>>>> Not that anything remotely recent supports tlbia but ...
>>>>>>>>>
>>>>>>>>> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>>>>>>>>> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
>>>>>>>>> ---
>>>>>>>>>  target-ppc/translate.c | 6 +++---
>>>>>>>>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>>>>>>>>
>>>>>>>>> diff --git a/target-ppc/translate.c b/target-ppc/translate.c
>>>>>>>>> index dfd3010..690ffd2 100644
>>>>>>>>> --- a/target-ppc/translate.c
>>>>>>>>> +++ b/target-ppc/translate.c
>>>>>>>>> @@ -4858,7 +4858,7 @@ static void gen_tlbie(DisasContext *ctx)
>>>>>>>>>  #if defined(CONFIG_USER_ONLY)
>>>>>>>>>      gen_inval_exception(ctx, POWERPC_EXCP_PRIV_OPC);
>>>>>>>>>  #else
>>>>>>>>> -    if (unlikely(ctx->pr)) {
>>>>>>>>> +    if (unlikely(ctx->pr || !ctx->hv)) {
>>>>>>>>>          gen_inval_exception(ctx, POWERPC_EXCP_PRIV_OPC);
>>>>>>>>>          return;
>>>>>>>>>      }
>>>>>>>>> @@ -4879,7 +4879,7 @@ static void gen_tlbsync(DisasContext *ctx)
>>>>>>>>>  #if defined(CONFIG_USER_ONLY)
>>>>>>>>>      gen_inval_exception(ctx, POWERPC_EXCP_PRIV_OPC);
>>>>>>>>>  #else
>>>>>>>>> -    if (unlikely(ctx->pr)) {
>>>>>>>>> +    if (unlikely(ctx->pr || !ctx->hv)) {
>>>>>>>>>          gen_inval_exception(ctx, POWERPC_EXCP_PRIV_OPC);
>>>>>>>>>          return;
>>>>>>>>>      }
>>>>>>>>> @@ -4898,7 +4898,7 @@ static void gen_slbia(DisasContext *ctx)
>>>>>>>>>  #if defined(CONFIG_USER_ONLY)
>>>>>>>>>      gen_inval_exception(ctx, POWERPC_EXCP_PRIV_OPC);
>>>>>>>>>  #else
>>>>>>>>> -    if (unlikely(ctx->pr)) {
>>>>>>>>> +    if (unlikely(ctx->pr || !ctx->hv)) {
>>>>>>>>>          gen_inval_exception(ctx, POWERPC_EXCP_PRIV_OPC);
>>>>>>>>>          return;
>>>>>>>>>      }
>>>>>>>>
>>>>>>>> Unfortunately this patch breaks qemu-system-ppc for both g3beige and
>>>>>>>> mac99 under TCG causing a freeze in OpenBIOS when starting
>>>>>>>> qemu-system-ppc with no parameters.
>>>>>>>
>>>>>>> Bother, sorry.
>>>>>>>
>>>>>>> I think this is because I applied this without the patch that treats
>>>>>>> machines with no hypervisor mode (e.g. Apples) as always being in
>>>>>>> hypervisor mode.
>>>>>>
>>>>>> No problem, I can cope for a couple of days or so.
>>>>>
>>>>> Cédric,
>>>>>
>>>>> Not sure if you've seen this thread, but one of the HV-mode patches
>>>>> caused a regression on Mac.  I think it's because I didn't include the
>>>>> other patch which treats Apple-mode PPCs as always having HV=1.
>>>>
>>>> I missed that as I didn't put myself in Cc :/ 
>>>>  
>>>>> Can you make sending your updated version of that patch a priority,
>>>>> even if the rest of the batch of HV patches isn't ready yet.
>>>>
>>>> sure. I will/should today or tomorrow. I suppose we want these patches :
>>>>
>>>> 	[05/12] ppc: Fix hreg_store_msr() so that non-HV mode cannot alter MSR:HV
>>>> 		http://patchwork.ozlabs.org/patch/618083/
>>>>
>>>> 	[07/12] ppc: Better figure out if processor has HV mode	
>>>> 		http://patchwork.ozlabs.org/patch/618089/
>>>>
>>>>
>>>> Mark,
>>>>
>>>> I tried to boot a darwinppc-602.iso with :
>>>>
>>>> 	qemu-system-ppc -M g3beige -cdrom darwinx86-602.iso -boot d
>>>>
>>>> but I get a :
>>>>
>>>> 	"No valid state has been set by load or ..."
>>>>
>>>> or we don't need to go further ? may be I need a newer FW.
>>>
>>> Hmmm that looks like you've got an x86 ISO there which is why
>>> OpenBIOS/PPC fails to execute the bootloader. The image I use for
>>> testing can be found here:
>>> https://opensource.apple.com/static/iso/darwinppc-602.cdr.gz (simply
>>> gunzip and then rename to .iso).
>>
>> Got it. much better with ppc :) ppc is not that omnipotent.
> 
> :)
> 
>>>> Could you try the two patches above please ? They apply on top of Dave's
>>>> ppc-for-2.7-20160531 and seem to have a good behavior with the small test
>>>> I could do.
>>>
>>> I'll try and take a look tomorrow, however in the meantime see if the
>>> above image enables you to replicate the issue locally.
>>
>>
>> so, on top of ppc-for-2.7-20160531, with your fix for :
>>
>> 	ppc: Use split I/D mmu modes to avoid flushes on interrupts
> 
> Unfortunately this isn't really a fix: the whole point of splitting the
> MMU modes is to be able to avoid these expensive cache flushes in the
> first place. Then again it could be that this is exposing an existing
> bug elsewhere...
> 
>> and these two patches :
>>
>>  	[05/12] ppc: Fix hreg_store_msr() so that non-HV mode cannot alter MSR:HV
>>  		http://patchwork.ozlabs.org/patch/618083/
>>
>>  	[07/12] ppc: Better figure out if processor has HV mode	
>>  		http://patchwork.ozlabs.org/patch/618089/
>>
>> The darwin cd boots correctly up to :
>>
>> 	...
>> 	The following devices are available for installation :
>>
>> and then loops on something. But I don't get a kernel panic anymore.
> 
> Yes, that effectively matches what I see here - glad that you are now
> able to reproduce this.

Just to add in case it wasn't clear from my previous reply - this is
actually the correct and expected behaviour. If you add a hard disk
device with -hda then it will appear on-screen below the prompt at which
point you can proceed with the installation as normal.


ATB,

Mark.