Re: [PATCH v12 2/7] s390x/cpu topology: reporting the CPU topology to the guest

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On 12/6/22 10:48, Janis Schoetterl-Glausch wrote:
On Tue, 2022-11-29 at 18:42 +0100, Pierre Morel wrote:
The guest uses the STSI instruction to get information on the
CPU topology.

Let us implement the STSI instruction for the basis CPU topology
level, level 2.

Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
---
  target/s390x/cpu.h          |  77 +++++++++++++++
  hw/s390x/s390-virtio-ccw.c  |  12 +--
  target/s390x/cpu_topology.c | 186 ++++++++++++++++++++++++++++++++++++
  target/s390x/kvm/kvm.c      |   6 +-
  target/s390x/meson.build    |   1 +
  5 files changed, 274 insertions(+), 8 deletions(-)
  create mode 100644 target/s390x/cpu_topology.c

diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index 7d6d01325b..dd878ac916 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h

[...]

+/* Configuration topology */
+typedef struct SysIB_151x {
+    uint8_t  reserved0[2];
+    uint16_t length;
+    uint8_t  mag[S390_TOPOLOGY_MAG];
+    uint8_t  reserved1;
+    uint8_t  mnest;
+    uint32_t reserved2;
+    char tle[0];

AFAIK [] is preferred over [0].

grr, yes, I think I have been already told so :)



+} QEMU_PACKED QEMU_ALIGNED(8) SysIB_151x;
+QEMU_BUILD_BUG_ON(sizeof(SysIB_151x) != 16);

[...]

+/*
+ * s390_topology_add_cpu:
+ * @topo: pointer to the topology
+ * @cpu : pointer to the new CPU
+ *
+ * The topology pointed by S390CPU, gives us the CPU topology
+ * established by the -smp QEMU aruments.
+ * The core-id is used to calculate the position of the CPU inside
+ * the topology:
+ *  - the socket, container TLE, containing the CPU, we have one socket
+ *    for every num_cores cores.
+ *  - the CPU TLE inside the socket, we have potentionly up to 4 CPU TLE
+ *    in a container TLE with the assumption that all CPU are identical
+ *    with the same polarity and entitlement because we have maximum 256
+ *    CPUs and each TLE can hold up to 64 identical CPUs.
+ *  - the bit in the 64 bit CPU TLE core mask
+ */
+static void s390_topology_add_cpu(S390Topology *topo, S390CPU *cpu)
+{
+    int core_id = cpu->env.core_id;
+    int bit, origin;
+    int socket_id;
+
+    cpu->machine_data = topo;
+    socket_id = core_id / topo->num_cores;
+    /*
+     * At the core level, each CPU is represented by a bit in a 64bit
+     * uint64_t which represent the presence of a CPU.
+     * The firmware assume that all CPU in a CPU TLE have the same
+     * type, polarization and are all dedicated or shared.
+     * In that case the origin variable represents the offset of the first
+     * CPU in the CPU container.
+     * More than 64 CPUs per socket are represented in several CPU containers
+     * inside the socket container.
+     * The only reason to have several S390TopologyCores inside a socket is
+     * to have more than 64 CPUs.
+     * In that case the origin variable represents the offset of the first CPU
+     * in the CPU container. More than 64 CPUs per socket are represented in
+     * several CPU containers inside the socket container.
+     */

This comment still contains redundant sentences.
Did you have a look at my suggestion in v10 patch 1?

Yes, I had, and sorry, I forgot to report here inside the patch 11.
I will take it, thanks for it.


+    bit = core_id;
+    origin = bit / 64;
+    bit %= 64;
+    bit = 63 - bit;
+
+    topo->socket[socket_id].active_count++;
+    set_bit(bit, &topo->socket[socket_id].mask[origin]);
+}
+
+/*
+ * s390_prepare_topology:
+ * @s390ms : pointer to the S390CcwMachite State
+ *
+ * Calls s390_topology_add_cpu to organize the topology
+ * inside the topology device before writing the SYSIB.
+ *
+ * The topology is currently fixed on boot and do not change

does not change

yes, thanks


regards,
Pierre

--
Pierre Morel
IBM Lab Boeblingen



[Index of Archives]     [KVM ARM]     [KVM ia64]     [KVM ppc]     [Virtualization Tools]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite Questions]     [Linux Kernel]     [Linux SCSI]     [XFree86]

  Powered by Linux