> -----Original Message----- > From: kvm-owner@xxxxxxxxxxxxxxx [mailto:kvm-owner@xxxxxxxxxxxxxxx] > On Behalf Of Babu Moger > Sent: Friday, June 15, 2018 12:16 PM > To: mst@xxxxxxxxxx; marcel.apfelbaum@xxxxxxxxx; pbonzini@xxxxxxxxxx; > rth@xxxxxxxxxxx; ehabkost@xxxxxxxxxx > Cc: qemu-devel@xxxxxxxxxx; mtosatti@xxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; > kash@xxxxxxxxxxxxxx; geoff@xxxxxxxxxxxxxxx; Moger, Babu > <Babu.Moger@xxxxxxx> > Subject: [PATCH v15 1/3] i386: Fix up the Node id for CPUID_8000_001E > > This is part of topoext support. To keep the compatibility, we need > to support all the combination of nr_cores and nr_threads currently > supported. With this combination, we might end up with more nodes than > we can support with real hardware. We need to fix up the node id to > accommodate more nodes here. We can achieve this by shifting the bits. > > Signed-off-by: Babu Moger <babu.moger@xxxxxxx> > --- > target/i386/cpu.c | 23 ++++++++++++++++++++++- > 1 file changed, 22 insertions(+), 1 deletion(-) > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > index 7a4484b..5246be4 100644 > --- a/target/i386/cpu.c > +++ b/target/i386/cpu.c > @@ -19,6 +19,7 @@ > > #include "qemu/osdep.h" > #include "qemu/cutils.h" > +#include "qemu/bitops.h" > > #include "cpu.h" > #include "exec/exec-all.h" > @@ -472,6 +473,8 @@ static void encode_topo_cpuid8000001e(CPUState > *cs, X86CPU *cpu, > uint32_t *ecx, uint32_t *edx) > { > struct core_topology topo = {0}; > + unsigned long nodes; > + int shift; > > build_core_topology(cs->nr_cores, cpu->core_id, &topo); > *eax = cpu->apic_id; > @@ -504,7 +507,25 @@ static void encode_topo_cpuid8000001e(CPUState > *cs, X86CPU *cpu, > * 2 Socket id > * 1:0 Node id > */ > - *ecx = ((topo.num_nodes - 1) << 8) | (cpu->socket_id << 2) | > topo.node_id; > + if (topo.num_nodes <= 4) { > + *ecx = ((topo.num_nodes - 1) << 8) | (cpu->socket_id << 2) | > + topo.node_id; > + } else { > + /* > + * Node id fix up. Actual hardware supports up to 4 nodes. But with > + * more than 32 cores, we may end up with more than 4 nodes. > + * Node id is a combination of socket id and node id. Only requirement > + * here is that this number should be unique accross the system. > + * Shift the socket id to accommodate more nodes. We dont expect > both > + * socket id and node id to be big number at the same time. This is not > + * an ideal config but we need to to support it. Max bit we can have > + * here is 8. > + */ > + nodes = topo.num_nodes - 1; > + shift = find_last_bit(&nodes, 8); > + *ecx = ((topo.num_nodes - 1) << 8) | (cpu->socket_id << shift) | Sorry. There is a bug here. This should be (cpu->socket_id << (shift + 1) ). I will fix it. Let me know the rest of the code. > + topo.node_id; > + } > *edx = 0; > } > > -- > 1.8.3.1
