[Qemu-devel] [RFC PATCH v2 4/5] xics: Use stable_cpu_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. Optionally change this to index the ICPState array by
stable_cpu_id. When the use of stable_cpu_id is enabled from pseries-2.7
onwards, this allows migration of guest to succeed when there are holes in
cpu_index range due to CPU core hot removal.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
---
 hw/intc/xics.c        | 21 +++++++++++++++++----
 hw/intc/xics_kvm.c    | 10 ++++------
 hw/intc/xics_spapr.c  | 29 +++++++++++++++++------------
 include/hw/ppc/xics.h |  1 +
 4 files changed, 39 insertions(+), 22 deletions(-)

diff --git a/hw/intc/xics.c b/hw/intc/xics.c
index cd48f42..97ff3c5 100644
--- a/hw/intc/xics.c
+++ b/hw/intc/xics.c
@@ -36,6 +36,17 @@
 #include "qemu/error-report.h"
 #include "qapi/visitor.h"
 
+int xics_get_server(PowerPCCPU *cpu)
+{
+    CPUState *cs = CPU(cpu);
+
+    if (cs->has_stable_cpu_id) {
+        return cs->stable_cpu_id;
+    } else {
+        return cs->cpu_index;
+    }
+}
+
 int xics_get_cpu_index_by_dt_id(int cpu_dt_id)
 {
     PowerPCCPU *cpu = ppc_get_vcpu_by_dt_id(cpu_dt_id);
@@ -50,9 +61,10 @@ 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];
+    int server = xics_get_server(cpu);
+    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 +75,11 @@ void xics_cpu_setup(XICSState *xics, PowerPCCPU *cpu)
 {
     CPUState *cs = CPU(cpu);
     CPUPPCState *env = &cpu->env;
-    ICPState *ss = &xics->ss[cs->cpu_index];
+    int server = xics_get_server(cpu);
+    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..f71b468 100644
--- a/hw/intc/xics_kvm.c
+++ b/hw/intc/xics_kvm.c
@@ -326,14 +326,12 @@ 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);
+    int server = xics_get_server(cpu);
+    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..5491f82 100644
--- a/hw/intc/xics_spapr.c
+++ b/hw/intc/xics_spapr.c
@@ -31,6 +31,7 @@
 #include "trace.h"
 #include "qemu/timer.h"
 #include "hw/ppc/spapr.h"
+#include "hw/ppc/spapr_cpu_core.h"
 #include "hw/ppc/xics.h"
 #include "qapi/visitor.h"
 #include "qapi/error.h"
@@ -42,17 +43,19 @@
 static target_ulong h_cppr(PowerPCCPU *cpu, sPAPRMachineState *spapr,
                            target_ulong opcode, target_ulong *args)
 {
-    CPUState *cs = CPU(cpu);
+    int server = xics_get_server(cpu);
     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->has_stable_cpu_id ? args[0] :
+                          xics_get_cpu_index_by_dt_id(args[0]);
     target_ulong mfrr = args[1];
 
     if (server >= spapr->xics->nr_servers) {
@@ -66,8 +69,8 @@ static target_ulong h_ipi(PowerPCCPU *cpu, sPAPRMachineState *spapr,
 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);
+    int server = xics_get_server(cpu);
+    uint32_t xirr = icp_accept(spapr->xics->ss + server);
 
     args[0] = xirr;
     return H_SUCCESS;
@@ -76,8 +79,8 @@ static target_ulong h_xirr(PowerPCCPU *cpu, sPAPRMachineState *spapr,
 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];
+    int server = xics_get_server(cpu);
+    ICPState *ss = &spapr->xics->ss[server];
     uint32_t xirr = icp_accept(ss);
 
     args[0] = xirr;
@@ -88,19 +91,19 @@ static target_ulong h_xirr_x(PowerPCCPU *cpu, sPAPRMachineState *spapr,
 static target_ulong h_eoi(PowerPCCPU *cpu, sPAPRMachineState *spapr,
                           target_ulong opcode, target_ulong *args)
 {
-    CPUState *cs = CPU(cpu);
+    int server = xics_get_server(cpu);
     target_ulong xirr = args[0];
 
-    icp_eoi(spapr->xics, cs->cpu_index, xirr);
+    icp_eoi(spapr->xics, server, xirr);
     return H_SUCCESS;
 }
 
 static target_ulong h_ipoll(PowerPCCPU *cpu, sPAPRMachineState *spapr,
                             target_ulong opcode, target_ulong *args)
 {
-    CPUState *cs = CPU(cpu);
+    int server = xics_get_server(cpu);
     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 +116,7 @@ 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 +126,8 @@ 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->has_stable_cpu_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)
diff --git a/include/hw/ppc/xics.h b/include/hw/ppc/xics.h
index 6189a3b..aea0678 100644
--- a/include/hw/ppc/xics.h
+++ b/include/hw/ppc/xics.h
@@ -195,5 +195,6 @@ void ics_write_xive(ICSState *ics, int nr, int server,
 void ics_set_irq_type(ICSState *ics, int srcno, bool lsi);
 
 int xics_find_source(XICSState *icp, int irq);
+int xics_get_server(PowerPCCPU *cpu);
 
 #endif /* __XICS_H__ */
-- 
2.7.4