On 19.12.2012, at 05:34, David Gibson wrote: > On Tue, Dec 18, 2012 at 12:49:02AM +0100, Alexander Graf wrote: >> >> On 18.12.2012, at 00:00, David Gibson wrote: >> >>> On Mon, Dec 17, 2012 at 11:10:12AM +0100, Alexander Graf wrote: >>>> >>>> >>>> On 17.12.2012, at 03:32, David Gibson <da...@gibson.dropbear.id.au> wrote: >>>> >>>>> On Thu, Dec 13, 2012 at 01:50:25PM +0100, Alexander Graf wrote: >>>>>> >>>>>> On 04.12.2012, at 03:42, David Gibson wrote: >>>>>> >>>>>>> PAPR requires that the device tree's CPU nodes have several properties >>>>>>> with information about the L1 cache. We created two of these >>>>>>> properties, but with incorrect names - "[id]cache-block-size" instead >>>>>>> of "[id]-cache-block-size" (note the extra hyphen). >>>>>>> >>>>>>> We were also missing some of the required cache properties. This >>>>>>> patch adds the [id]-cache-line-size properties (which have the same >>>>>>> values as the block size properties in all current cases). We also >>>>>>> add the [id]-cache-size properties. The latter requires some extra >>>>>>> infrastructure in the general target-ppc code to (optionally) set the >>>>>>> cache sizes for various CPUs. We obtain the published values either >>>>>>> from there, or from the host when KVM is in use. >>>>>>> >>>>>>> Signed-off-by: David Gibson <da...@gibson.dropbear.id.au> >>>>>>> --- >>>>>>> hw/spapr.c | 20 ++++++++++++++++++-- >>>>>>> target-ppc/cpu.h | 1 + >>>>>>> target-ppc/kvm.c | 10 ++++++++++ >>>>>>> target-ppc/kvm_ppc.h | 12 ++++++++++++ >>>>>>> target-ppc/translate_init.c | 4 ++++ >>>>>>> 5 files changed, 45 insertions(+), 2 deletions(-) >>>>>>> >>>>>>> diff --git a/hw/spapr.c b/hw/spapr.c >>>>>>> index d23aa9d..3bacf2f 100644 >>>>>>> --- a/hw/spapr.c >>>>>>> +++ b/hw/spapr.c >>>>>>> @@ -315,6 +315,10 @@ static void *spapr_create_fdt_skel(const char >>>>>>> *cpu_model, >>>>>>> 0xffffffff, 0xffffffff}; >>>>>>> uint32_t tbfreq = kvm_enabled() ? kvmppc_get_tbfreq() : >>>>>>> TIMEBASE_FREQ; >>>>>>> uint32_t cpufreq = kvm_enabled() ? kvmppc_get_clockfreq() : >>>>>>> 1000000000; >>>>>>> + int dcache_size = kvm_enabled() ? kvmppc_get_dcache_size() >>>>>>> + : env->l1_dcache_size; >>>>>>> + int icache_size = kvm_enabled() ? kvmppc_get_icache_size() >>>>>>> + : env->l1_icache_size; >>>>>> >>>>>> By default with KVM we use -cpu host, right? So we already should >>>>>> get the correct cache sizes for the CPU you're on. >>>>> >>>>> Um.. sort of. The first problem with that is that I only just added >>>>> the cache size information to qemu, so only a few CPUs currently >>>>> populate that information. Using the host info means we can get the >>>>> right information even for CPUs that don't yet have cache info in >>>>> qemu. >>>>> >>>>>> Imagine we would support the compatibility feature where you could >>>>>> run with -cpu POWER6 on a POWER7 machine. Would exposing the POWER6 >>>>>> cache size rather than the host's make any real difference to the >>>>>> guest? Or would it work nevertheless? >>>>> >>>>> The second problem is that there may be circumstances where the >>>>> cache size is altered from the normal size for the cpu. Running in >>>>> POWER6 compat mode >>>> >>>> Well, either we want to be compatible or we don't :). If we run with >>>> -cpu POWER6 we want to generate the same dt as we did on a POWER6 >>>> system itself. >>> >>> Hrm. Ok. >>> >>> So, the remaining difficulty I have with that is that for -cpu HOST we >>> should still take the cache sizes from the host, but that can't easily >>> be done because they're only stored in the env, not the cpu_def. >> >> Can we set a bit somewhere that allows us to do a sanity check >> later? After all, the values coming from the host and the values in >> the populated env really should just be identical for -cpu >> host. Every time they're not, it's simply a bug that needs to be >> reported. > > That works. Although it's not obvious where to put the check and > fixup. kvmppc_fixup_cpu() seems like the obvious place, but that's no > good because it's called before the per-cpu-type init function, which > is what populates the expected cachesize values.
That's a real shame. Any reason we don't run it after the init function? Fixup indicates that it fixes things up after they happened, not before :). Alex
