On 26.08.2013, at 08:46, Aneesh Kumar K.V wrote: > Alexander Graf <ag...@suse.de> writes: > >> On 23.08.2013, at 06:20, Aneesh Kumar K.V wrote: >> >>> From: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com> >>> >>> Without this, a value of rb=0 and rs=0 results in replacing the 0th >>> index. This can be observed when using gdb remote debugging support. >>> >>> (gdb) x/10i do_fork >>> 0xc000000000085330 <do_fork>: Cannot access memory at address >>> 0xc000000000085330 >>> (gdb) >>> >>> This is because when we do the slb sync via kvm_cpu_synchronize_state, >>> we overwrite the slb entry (0th entry) for 0xc000000000085330 >>> >>> Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> >>> --- >>> target-ppc/kvm.c | 20 ++++++++++++++++++-- >>> 1 file changed, 18 insertions(+), 2 deletions(-) >>> >>> diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c >>> index 30a870e..6878af2 100644 >>> --- a/target-ppc/kvm.c >>> +++ b/target-ppc/kvm.c >>> @@ -1033,9 +1033,25 @@ int kvm_arch_get_registers(CPUState *cs) >>> >>> /* Sync SLB */ >>> #ifdef TARGET_PPC64 >>> + /* >>> + * KVM_GET_SREGS doesn't return slb entry with slot information >>> + * same as index. The ioctl zero fills the array and update only >>> + * upto slb_max entries. We cannot depend on the slot value >>> + * in the slbe field for update, because a zero slbe value would >>> + * result in us wrongly updating the 0th index. Instead we zero >>> fill >>> + * the env->slb array first so that we mark all entries invalid and >>> + * update with only valid SLB entries. >> >> Still too negative. How about something like this: >> >> /* >> * The packed SLB array we get from KVM only contains information >> * about valid entries. So we flush our internal copy to get rid of stale >> * ones, then put all valid SLB entries back in. >> */ > > updated > >> >>> + */ >>> + memset(env->slb, 0, 64 * sizeof(ppc_slb_t)); >> >> Can't we use ARRAY_SIZE here and below? > > I was thinking we want to be explicit there saying we are zeroing out all > the 64 entries. I could do sizeof(env->slb).
Yup, that works too. In the loop below s/64/ARRAY_SIZE(env->slb)/ should work too I think. Alex
