[Qemu-devel] [RFC PATCH v1 4/5] xics: Use migration_id instead of cpu_index in XICS code

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

xics maintains an array of ICPState structures which is indexed
by cpu_index. Change this to index the ICPState array by migration_id
for pseries-2.7 onwards. This allows migration of guest to suceed
when there are holes in cpu_index range due to CPU hot removal.

NOTE: In rtas_set_xive() and h_ipi(), cpu_dt_id is implicitly
assume to be equivalent to migration_id.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
---
 hw/intc/xics.c       | 12 ++++++++----
 hw/intc/xics_kvm.c   | 11 +++++------
 hw/intc/xics_spapr.c | 28 +++++++++++++++++++++-------
 3 files changed, 34 insertions(+), 17 deletions(-)

diff --git a/hw/intc/xics.c b/hw/intc/xics.c
index cd48f42..ce7571e 100644
--- a/hw/intc/xics.c
+++ b/hw/intc/xics.c
@@ -50,9 +50,11 @@ int xics_get_cpu_index_by_dt_id(int cpu_dt_id)
 void xics_cpu_destroy(XICSState *xics, PowerPCCPU *cpu)
 {
     CPUState *cs = CPU(cpu);
-    ICPState *ss = &xics->ss[cs->cpu_index];
+    CPUClass *cc = CPU_GET_CLASS(cs);
+    int server = cc->get_migration_id(cs);
+    ICPState *ss = &xics->ss[server];
 
-    assert(cs->cpu_index < xics->nr_servers);
+    assert(server < xics->nr_servers);
     assert(cs == ss->cs);
 
     ss->output = NULL;
@@ -63,10 +65,12 @@ void xics_cpu_setup(XICSState *xics, PowerPCCPU *cpu)
 {
     CPUState *cs = CPU(cpu);
     CPUPPCState *env = &cpu->env;
-    ICPState *ss = &xics->ss[cs->cpu_index];
+    CPUClass *cc = CPU_GET_CLASS(cs);
+    int server = cc->get_migration_id(cs);
+    ICPState *ss = &xics->ss[server];
     XICSStateClass *info = XICS_COMMON_GET_CLASS(xics);
 
-    assert(cs->cpu_index < xics->nr_servers);
+    assert(server < xics->nr_servers);
 
     ss->cs = cs;
 
diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
index edbd62f..2c087a4 100644
--- a/hw/intc/xics_kvm.c
+++ b/hw/intc/xics_kvm.c
@@ -326,14 +326,13 @@ static const TypeInfo ics_kvm_info = {
  */
 static void xics_kvm_cpu_setup(XICSState *xics, PowerPCCPU *cpu)
 {
-    CPUState *cs;
-    ICPState *ss;
+    CPUState *cs = CPU(cpu);
     KVMXICSState *xicskvm = XICS_SPAPR_KVM(xics);
+    CPUClass *cc = CPU_GET_CLASS(cs);
+    int server = cc->get_migration_id(cs);
+    ICPState *ss = ss = &xics->ss[server];
 
-    cs = CPU(cpu);
-    ss = &xics->ss[cs->cpu_index];
-
-    assert(cs->cpu_index < xics->nr_servers);
+    assert(server < 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 618826d..281ba76 100644
--- a/hw/intc/xics_spapr.c
+++ b/hw/intc/xics_spapr.c
@@ -43,16 +43,20 @@ static target_ulong h_cppr(PowerPCCPU *cpu, sPAPRMachineState *spapr,
                            target_ulong opcode, target_ulong *args)
 {
     CPUState *cs = CPU(cpu);
+    CPUClass *cc = CPU_GET_CLASS(cs);
+    int server = cc->get_migration_id(cs);
     target_ulong cppr = args[0];
 
-    icp_set_cppr(spapr->xics, cs->cpu_index, cppr);
+    icp_set_cppr(spapr->xics, server, cppr);
     return H_SUCCESS;
 }
 
 static target_ulong h_ipi(PowerPCCPU *cpu, sPAPRMachineState *spapr,
                           target_ulong opcode, target_ulong *args)
 {
-    target_ulong server = xics_get_cpu_index_by_dt_id(args[0]);
+    CPUState *cs = CPU(cpu);
+    target_ulong server = cs->use_migration_id ? args[0] :
+                          xics_get_cpu_index_by_dt_id(args[0]);
     target_ulong mfrr = args[1];
 
     if (server >= spapr->xics->nr_servers) {
@@ -67,7 +71,9 @@ 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);
+    CPUClass *cc = CPU_GET_CLASS(cs);
+    int server = cc->get_migration_id(cs);
+    uint32_t xirr = icp_accept(spapr->xics->ss + server);
 
     args[0] = xirr;
     return H_SUCCESS;
@@ -77,7 +83,9 @@ 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];
+    CPUClass *cc = CPU_GET_CLASS(cs);
+    int server = cc->get_migration_id(cs);
+    ICPState *ss = &spapr->xics->ss[server];
     uint32_t xirr = icp_accept(ss);
 
     args[0] = xirr;
@@ -89,9 +97,11 @@ static target_ulong h_eoi(PowerPCCPU *cpu, sPAPRMachineState *spapr,
                           target_ulong opcode, target_ulong *args)
 {
     CPUState *cs = CPU(cpu);
+    CPUClass *cc = CPU_GET_CLASS(cs);
+    int server = cc->get_migration_id(cs);
     target_ulong xirr = args[0];
 
-    icp_eoi(spapr->xics, cs->cpu_index, xirr);
+    icp_eoi(spapr->xics, server, xirr);
     return H_SUCCESS;
 }
 
@@ -99,8 +109,10 @@ static target_ulong h_ipoll(PowerPCCPU *cpu, sPAPRMachineState *spapr,
                             target_ulong opcode, target_ulong *args)
 {
     CPUState *cs = CPU(cpu);
+    CPUClass *cc = CPU_GET_CLASS(cs);
+    int server = cc->get_migration_id(cs);
     uint32_t mfrr;
-    uint32_t xirr = icp_ipoll(spapr->xics->ss + cs->cpu_index, &mfrr);
+    uint32_t xirr = icp_ipoll(spapr->xics->ss + server, &mfrr);
 
     args[0] = xirr;
     args[1] = mfrr;
@@ -113,6 +125,7 @@ static void rtas_set_xive(PowerPCCPU *cpu, sPAPRMachineState *spapr,
                           uint32_t nargs, target_ulong args,
                           uint32_t nret, target_ulong rets)
 {
+    CPUState *cs = CPU(cpu);
     ICSState *ics = spapr->xics->ics;
     uint32_t nr, server, priority;
 
@@ -122,7 +135,8 @@ static void rtas_set_xive(PowerPCCPU *cpu, sPAPRMachineState *spapr,
     }
 
     nr = rtas_ld(args, 0);
-    server = xics_get_cpu_index_by_dt_id(rtas_ld(args, 1));
+    server = cs->use_migration_id ? rtas_ld(args, 1) :
+             xics_get_cpu_index_by_dt_id(rtas_ld(args, 1));
     priority = rtas_ld(args, 2);
 
     if (!ics_valid_irq(ics, nr) || (server >= ics->xics->nr_servers)
-- 
2.7.4