[RFC 3/4] ppc/spapr: Add support for 'ibm, open-errinjct' and 'ibm, close-errinjct'

[Narayana Murty N <nnmlinux@linux.ibm.com>]

Add support for the 'ibm,open-errinjct' and 'ibm,close-errinjct' RTAS
calls. These handlers manage exclusive access to error injection
facilities through a simple session-based mechanism.

Updates include:
  - Implementation of rtas_ibm_open_errinjct() and rtas_ibm_close_errinjct()
  - Tracking field 'spapr->errinjct_token' in SpaprMachineState
  - New token definitions for the above RTAS calls
  - Return codes for already open or invalid close conditions

This ensures that only one guest process can actively perform error
injection at a time, improving reliability and preventing conflicts.

Signed-off-by: Narayana Murty N <nnmlinux@linux.ibm.com>
---
---
 include/hw/ppc/spapr.h |  8 +++++-
 hw/ppc/spapr_pci.c     | 65 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index f762be030c..af9617b13e 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -283,6 +283,7 @@ struct SpaprMachineState {
     Error *fwnmi_migration_blocker;
 
     SpaprWatchdog wds[WDT_MAX_WATCHDOGS];
+    uint32_t errinjct_token;
 };
 
 #define H_SUCCESS         0
@@ -755,6 +756,9 @@ enum rtas_err_type {
 #define RTAS_OUT_PARAM_ERROR                    -3
 #define RTAS_OUT_NOT_SUPPORTED                  -3
 #define RTAS_OUT_NO_SUCH_INDICATOR              -3
+#define RTAS_OUT_ALREADY_OPEN                   -4
+#define RTAS_OUT_NOT_OPEN                       -5
+#define RTAS_OUT_CLOSE_ERROR                    -6
 #define RTAS_OUT_NOT_AUTHORIZED                 -9002
 #define RTAS_OUT_SYSPARM_PARAM_ERROR            -9999
 
@@ -818,8 +822,10 @@ enum rtas_err_type {
 #define RTAS_IBM_NMI_REGISTER                   (RTAS_TOKEN_BASE + 0x2B)
 #define RTAS_IBM_NMI_INTERLOCK                  (RTAS_TOKEN_BASE + 0x2C)
 #define RTAS_IBM_ERRINJCT                       (RTAS_TOKEN_BASE + 0x2D)
+#define RTAS_IBM_OPEN_ERRINJCT                  (RTAS_TOKEN_BASE + 0x2E)
+#define RTAS_IBM_CLOSE_ERRINJCT                 (RTAS_TOKEN_BASE + 0x2F)
 
-#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2E)
+#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x30)
 
 /* RTAS ibm,get-system-parameter token values */
 #define RTAS_SYSPARM_SPLPAR_CHARACTERISTICS      20
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 219099f5aa..4723b87c65 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -864,6 +864,65 @@ param_error_exit:
     rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
 }
 
+static void rtas_ibm_open_errinjct(PowerPCCPU *cpu,
+                                   SpaprMachineState *spapr,
+                                   uint32_t token,
+                                   uint32_t nargs,
+                                   target_ulong args,
+                                   uint32_t nret,
+                                   target_ulong rets)
+{
+    /* Validate argument count */
+    if ((nargs != 0) || (nret != 2)) {
+        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
+        return;
+    }
+
+    if (spapr->errinjct_token) {
+        /* Already open: return token=0 and code=ALREADY_OPEN */
+        rtas_st(rets, 0, 0);
+        rtas_st(rets, 1, RTAS_OUT_ALREADY_OPEN);
+        return;
+    }
+
+    spapr->errinjct_token = 1;
+
+    /*
+     * Unlike most RTAS calls, ibm,open-errinjct returns
+     * the session token in the first output parameter
+     * and the status in the second.
+     */
+    rtas_st(rets, 0, spapr->errinjct_token);
+    rtas_st(rets, 1, RTAS_OUT_SUCCESS);
+}
+
+static void rtas_ibm_close_errinjct(PowerPCCPU *cpu,
+                                    SpaprMachineState *spapr,
+                                    uint32_t token,
+                                    uint32_t nargs,
+                                    target_ulong args,
+                                    uint32_t nret,
+                                    target_ulong rets)
+{
+    uint32_t o_token;
+
+    if ((nargs != 1) || (nret != 1)) {
+        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
+        return;
+    }
+
+    o_token = rtas_ld(args, 0);
+
+    if (o_token != spapr->errinjct_token) {
+        rtas_st(rets, 0, RTAS_OUT_NOT_OPEN);
+        return;
+    }
+
+    spapr->errinjct_token = 0;
+
+    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
+}
+
 static void pci_spapr_set_irq(void *opaque, int irq_num, int level)
 {
     /*
@@ -2560,6 +2619,12 @@ void spapr_pci_rtas_init(void)
     spapr_rtas_register(RTAS_IBM_ERRINJCT,
                         "ibm,errinjct",
                         rtas_ibm_errinjct);
+    spapr_rtas_register(RTAS_IBM_OPEN_ERRINJCT,
+                        "ibm,open-errinjct",
+                        rtas_ibm_open_errinjct);
+    spapr_rtas_register(RTAS_IBM_CLOSE_ERRINJCT,
+                        "ibm,close-errinjct",
+                        rtas_ibm_close_errinjct);
 }
 
 static void spapr_pci_register_types(void)
-- 
2.51.0