[Qemu-devel] [PATCH v4 13/20] ppc/xics: introduce helpers to find an ICP from some (CPU) index

[Cédric Le Goater]

Today, the Interrupt Presentation Controllers (ICP) are stored in an
array under the base class XICSState. They are simply indexed using
the CPU index field of CPUState. This made sense for the current
derived classes, spapr and kvm, as the CPU index are contiguous.
Nevertheless some problems have started to occur with CPU hotplug.

With the PowerNV platform CPUs, this is not true anymore. Real HW ids
are being used and they are not contiguous. So we need a way to
customize the lookups in the array. Below is a proposal for this
purpose. A couple of helpers are introduced to hide the nature of the
underlying ICP array and also a new XICSStateClass method 'find_icp'
to let the derived classes customize the ICP lookups.

A followup patch would be to let the derived class decide on the ICP
storage. They could use a hash table for instance. We would need to
introduce a new class method 'get_icp' for that. Or simply, change the
ICP array for a hash table and let the derived class decide on the key
to use.

Signed-off-by: Cédric Le Goater <address@hidden>
---
 hw/intc/xics.c        | 48 ++++++++++++++++++++++++++++++++++++------------
 hw/intc/xics_kvm.c    |  7 ++-----
 hw/intc/xics_spapr.c  | 12 ++++++------
 include/hw/ppc/xics.h |  2 ++
 4 files changed, 46 insertions(+), 23 deletions(-)

diff --git a/hw/intc/xics.c b/hw/intc/xics.c
index 3bbbcc847791..876c472aaa69 100644
--- a/hw/intc/xics.c
+++ b/hw/intc/xics.c
@@ -48,12 +48,32 @@ int xics_get_cpu_index_by_dt_id(int cpu_dt_id)
     return -1;
 }
 
+ICPState *xics_find_icp(XICSState *xics, int cpu_index)
+{
+    XICSStateClass *xsc = XICS_COMMON_GET_CLASS(xics);
+    ICPState *icp = xsc->find_icp(xics, cpu_index);
+
+    assert(icp);
+
+    return icp;
+}
+
+static ICPState *xics_get_icp(XICSState *xics, CPUState *cs)
+{
+    ICPState *ss;
+
+    assert(cs->cpu_index < xics->nr_servers);
+
+    ss = &xics->ss[cs->cpu_index];
+    ss->cs = cs;
+    return ss;
+}
+
 void xics_cpu_destroy(XICSState *xics, PowerPCCPU *cpu)
 {
     CPUState *cs = CPU(cpu);
-    ICPState *ss = &xics->ss[cs->cpu_index];
+    ICPState *ss = xics_find_icp(xics, cs->cpu_index);
 
-    assert(cs->cpu_index < xics->nr_servers);
     assert(cs == ss->cs);
 
     ss->output = NULL;
@@ -64,13 +84,9 @@ void xics_cpu_setup(XICSState *xics, PowerPCCPU *cpu)
 {
     CPUState *cs = CPU(cpu);
     CPUPPCState *env = &cpu->env;
-    ICPState *ss = &xics->ss[cs->cpu_index];
+    ICPState *ss = xics_get_icp(xics, cs);
     XICSStateClass *info = XICS_COMMON_GET_CLASS(xics);
 
-    assert(cs->cpu_index < xics->nr_servers);
-
-    ss->cs = cs;
-
     if (info->cpu_setup) {
         info->cpu_setup(xics, cpu);
     }
@@ -94,6 +110,12 @@ void xics_cpu_setup(XICSState *xics, PowerPCCPU *cpu)
 /*
  * XICS Common class - parent for emulated XICS and KVM-XICS
  */
+
+static ICPState *xics_common_find_icp(XICSState *xics, int cpu_index)
+{
+    return &xics->ss[cpu_index];
+}
+
 static void xics_common_reset(DeviceState *d)
 {
     XICSState *xics = XICS_COMMON(d);
@@ -191,8 +213,10 @@ static void xics_common_initfn(Object *obj)
 static void xics_common_class_init(ObjectClass *oc, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(oc);
+    XICSStateClass *xsc = XICS_COMMON_CLASS(oc);
 
     dc->reset = xics_common_reset;
+    xsc->find_icp = xics_common_find_icp;
 }
 
 static const TypeInfo xics_common_info = {
@@ -261,7 +285,7 @@ static void icp_check_ipi(ICPState *ss)
 
 static void icp_resend(XICSState *xics, int server)
 {
-    ICPState *ss = xics->ss + server;
+    ICPState *ss = xics_find_icp(xics, server);
     ICSState *ics;
 
     if (ss->mfrr < CPPR(ss)) {
@@ -274,7 +298,7 @@ static void icp_resend(XICSState *xics, int server)
 
 void icp_set_cppr(XICSState *xics, int server, uint8_t cppr)
 {
-    ICPState *ss = xics->ss + server;
+    ICPState *ss = xics_find_icp(xics, server);
     uint8_t old_cppr;
     uint32_t old_xisr;
 
@@ -301,7 +325,7 @@ void icp_set_cppr(XICSState *xics, int server, uint8_t cppr)
 
 void icp_set_mfrr(XICSState *xics, int server, uint8_t mfrr)
 {
-    ICPState *ss = xics->ss + server;
+    ICPState *ss = xics_find_icp(xics, server);
 
     ss->mfrr = mfrr;
     if (mfrr < CPPR(ss)) {
@@ -333,7 +357,7 @@ uint32_t icp_ipoll(ICPState *ss, uint32_t *mfrr)
 
 void icp_eoi(XICSState *xics, int server, uint32_t xirr)
 {
-    ICPState *ss = xics->ss + server;
+    ICPState *ss = xics_find_icp(xics, server);
     ICSState *ics;
     uint32_t irq;
 
@@ -354,7 +378,7 @@ void icp_eoi(XICSState *xics, int server, uint32_t xirr)
 static void icp_irq(ICSState *ics, int server, int nr, uint8_t priority)
 {
     XICSState *xics = ics->xics;
-    ICPState *ss = xics->ss + server;
+    ICPState *ss = xics_find_icp(xics, server);
 
     trace_xics_icp_irq(server, nr, priority);
 
diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
index 9c2f198fd142..b666bb59fc24 100644
--- a/hw/intc/xics_kvm.c
+++ b/hw/intc/xics_kvm.c
@@ -326,14 +326,11 @@ static const TypeInfo ics_kvm_info = {
  */
 static void xics_kvm_cpu_setup(XICSState *xics, PowerPCCPU *cpu)
 {
-    CPUState *cs;
-    ICPState *ss;
+    CPUState *cs = CPU(cpu);
+    ICPState *ss = xics_find_icp(xics, cs->cpu_index);
     KVMXICSState *xicskvm = XICS_SPAPR_KVM(xics);
     int ret;
 
-    cs = CPU(cpu);
-    ss = &xics->ss[cs->cpu_index];
-
     assert(cs->cpu_index < xics->nr_servers);
     if (xicskvm->kernel_xics_fd == -1) {
         abort();
diff --git a/hw/intc/xics_spapr.c b/hw/intc/xics_spapr.c
index e8d0623c2cb5..af29998b1255 100644
--- a/hw/intc/xics_spapr.c
+++ b/hw/intc/xics_spapr.c
@@ -67,9 +67,9 @@ static target_ulong h_xirr(PowerPCCPU *cpu, sPAPRMachineState 
*spapr,
                            target_ulong opcode, target_ulong *args)
 {
     CPUState *cs = CPU(cpu);
-    uint32_t xirr = icp_accept(spapr->xics->ss + cs->cpu_index);
+    ICPState *ss = xics_find_icp(spapr->xics, cs->cpu_index);
 
-    args[0] = xirr;
+    args[0] = icp_accept(ss);
     return H_SUCCESS;
 }
 
@@ -77,10 +77,9 @@ static target_ulong h_xirr_x(PowerPCCPU *cpu, 
sPAPRMachineState *spapr,
                              target_ulong opcode, target_ulong *args)
 {
     CPUState *cs = CPU(cpu);
-    ICPState *ss = &spapr->xics->ss[cs->cpu_index];
-    uint32_t xirr = icp_accept(ss);
+    ICPState *ss = xics_find_icp(spapr->xics, cs->cpu_index);
 
-    args[0] = xirr;
+    args[0] = icp_accept(ss);
     args[1] = cpu_get_host_ticks();
     return H_SUCCESS;
 }
@@ -99,8 +98,9 @@ static target_ulong h_ipoll(PowerPCCPU *cpu, 
sPAPRMachineState *spapr,
                             target_ulong opcode, target_ulong *args)
 {
     CPUState *cs = CPU(cpu);
+    ICPState *ss = xics_find_icp(spapr->xics, cs->cpu_index);
     uint32_t mfrr;
-    uint32_t xirr = icp_ipoll(spapr->xics->ss + cs->cpu_index, &mfrr);
+    uint32_t xirr = icp_ipoll(ss, &mfrr);
 
     args[0] = xirr;
     args[1] = mfrr;
diff --git a/include/hw/ppc/xics.h b/include/hw/ppc/xics.h
index ca9f8da542e0..52c426d409c9 100644
--- a/include/hw/ppc/xics.h
+++ b/include/hw/ppc/xics.h
@@ -76,6 +76,7 @@ struct XICSStateClass {
     void (*cpu_setup)(XICSState *icp, PowerPCCPU *cpu);
     void (*set_nr_irqs)(XICSState *icp, uint32_t nr_irqs, Error **errp);
     void (*set_nr_servers)(XICSState *icp, uint32_t nr_servers, Error **errp);
+    ICPState *(*find_icp)(XICSState *xics, int cpu_index);
 };
 
 struct XICSState {
@@ -206,5 +207,6 @@ void ics_set_irq_type(ICSState *ics, int srcno, bool lsi);
 ICSState *xics_find_source(XICSState *icp, int irq);
 
 void xics_hmp_info_pic(Monitor *mon, const QDict *qdict);
+ICPState *xics_find_icp(XICSState *xics, int cpu_index);
 
 #endif /* XICS_H */
-- 
2.7.4