[Qemu-devel] [PATCH] PPC: e500: Only expose even TLB sizes in initial TLB

[Qemu-devel] [PATCH] PPC: e500: Only expose even TLB sizes in initial TLB

[Alexander Graf]

When booting our e500 machine, we automatically generate a big TLB entry
in TLB1 that covers all of the code we need to run in there until the guest
can handle its TLB on its own.

However, e500v2 can only handle MAS1.0 sizes. However, we keep our TLB
information in MAS2.0 layout, which means we have twice as many TLB sizes
to choose from. That also means we can run into a situation where we try
to add a TLB size that could not fit into the MAS1.0 size bits.

Fix it by making sure we always have the lower bit set to 0. That way we
are always guaranteed to have MAS1.0 compatible TLB size information.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 hw/ppc/e500.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/hw/ppc/e500.c b/hw/ppc/e500.c
index feb712e..d23f9b2 100644
--- a/hw/ppc/e500.c
+++ b/hw/ppc/e500.c
@@ -362,6 +362,10 @@ static void mmubooke_create_initial_mapping(CPUPPCState *env)
        the device tree top */
     dt_end = bi->dt_base + bi->dt_size;
     ps = booke206_page_size_to_tlb(dt_end) + 1;
+    if (ps & 1) {
+        /* e500v2 can only do even TLB size bits */
+        ps++;
+    }
     size = (ps << MAS1_TSIZE_SHIFT);
     tlb->mas1 = MAS1_VALID | size;
     tlb->mas2 = 0;
-- 
1.6.0.2

Re: [Qemu-devel] [PATCH] PPC: e500: Only expose even TLB sizes in initial TLB

[Aurelien Jarno]

On Thu, Oct 04, 2012 at 06:55:35PM +0200, Alexander Graf wrote:
> When booting our e500 machine, we automatically generate a big TLB entry
> in TLB1 that covers all of the code we need to run in there until the guest
> can handle its TLB on its own.
> 
> However, e500v2 can only handle MAS1.0 sizes. However, we keep our TLB
> information in MAS2.0 layout, which means we have twice as many TLB sizes
> to choose from. That also means we can run into a situation where we try
> to add a TLB size that could not fit into the MAS1.0 size bits.
> 
> Fix it by making sure we always have the lower bit set to 0. That way we
> are always guaranteed to have MAS1.0 compatible TLB size information.
> 
> Signed-off-by: Alexander Graf <agraf@suse.de>
> ---
>  hw/ppc/e500.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/hw/ppc/e500.c b/hw/ppc/e500.c
> index feb712e..d23f9b2 100644
> --- a/hw/ppc/e500.c
> +++ b/hw/ppc/e500.c
> @@ -362,6 +362,10 @@ static void mmubooke_create_initial_mapping(CPUPPCState *env)
>         the device tree top */
>      dt_end = bi->dt_base + bi->dt_size;
>      ps = booke206_page_size_to_tlb(dt_end) + 1;
> +    if (ps & 1) {
> +        /* e500v2 can only do even TLB size bits */
> +        ps++;
> +    }
>      size = (ps << MAS1_TSIZE_SHIFT);
>      tlb->mas1 = MAS1_VALID | size;
>      tlb->mas2 = 0;

Applied (actually as part of the PPC pull).


-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net

Re: [Qemu-devel] [PATCH] PPC: e500: Only expose even TLB sizes in initial TLB

[Alexander Graf]

On 06.10.2012, at 20:35, Aurelien Jarno <aurelien@aurel32.net> wrote:

> On Thu, Oct 04, 2012 at 06:55:35PM +0200, Alexander Graf wrote:
>> When booting our e500 machine, we automatically generate a big TLB entry
>> in TLB1 that covers all of the code we need to run in there until the guest
>> can handle its TLB on its own.
>> 
>> However, e500v2 can only handle MAS1.0 sizes. However, we keep our TLB
>> information in MAS2.0 layout, which means we have twice as many TLB sizes
>> to choose from. That also means we can run into a situation where we try
>> to add a TLB size that could not fit into the MAS1.0 size bits.
>> 
>> Fix it by making sure we always have the lower bit set to 0. That way we
>> are always guaranteed to have MAS1.0 compatible TLB size information.
>> 
>> Signed-off-by: Alexander Graf <agraf@suse.de>
>> ---
>> hw/ppc/e500.c |    4 ++++
>> 1 files changed, 4 insertions(+), 0 deletions(-)
>> 
>> diff --git a/hw/ppc/e500.c b/hw/ppc/e500.c
>> index feb712e..d23f9b2 100644
>> --- a/hw/ppc/e500.c
>> +++ b/hw/ppc/e500.c
>> @@ -362,6 +362,10 @@ static void mmubooke_create_initial_mapping(CPUPPCState *env)
>>        the device tree top */
>>     dt_end = bi->dt_base + bi->dt_size;
>>     ps = booke206_page_size_to_tlb(dt_end) + 1;
>> +    if (ps & 1) {
>> +        /* e500v2 can only do even TLB size bits */
>> +        ps++;
>> +    }
>>     size = (ps << MAS1_TSIZE_SHIFT);
>>     tlb->mas1 = MAS1_VALID | size;
>>     tlb->mas2 = 0;
> 
> Applied (actually as part of the PPC pull).

Yes, these were quite critical bugfixes that I folded into the pull request. Sorry for not noting it anywhere :).

Alex

> 
> 
> -- 
> Aurelien Jarno                          GPG: 1024D/F1BCDB73
> aurelien@aurel32.net                 http://www.aurel32.net