[PATCH v16 5/7] ppc: spapr: Handle "ibm, nmi-register" and "ibm, nmi-interlock" RTAS calls

[Ganesh Goudar <ganeshgr@linux.ibm.com>]

From: Aravinda Prasad <arawinda.p@gmail.com>

This patch adds support in QEMU to handle "ibm,nmi-register"
and "ibm,nmi-interlock" RTAS calls.

The machine check notification address is saved when the
OS issues "ibm,nmi-register" RTAS call.

This patch also handles the case when multiple processors
experience machine check at or about the same time by
handling "ibm,nmi-interlock" call. In such cases, as per
PAPR, subsequent processors serialize waiting for the first
processor to issue the "ibm,nmi-interlock" call. The second
processor that also received a machine check error waits
till the first processor is done reading the error log.
The first processor issues "ibm,nmi-interlock" call
when the error log is consumed.

[Move fwnmi registeration to .apply hook]
Signed-off-by: Ganesh Goudar <ganeshgr@linux.ibm.com>
Signed-off-by: Aravinda Prasad <arawinda.p@gmail.com>
---
 hw/ppc/spapr_caps.c    |  9 +++++--
 hw/ppc/spapr_rtas.c    | 57 ++++++++++++++++++++++++++++++++++++++++++
 include/hw/ppc/spapr.h |  5 +++-
 3 files changed, 68 insertions(+), 3 deletions(-)

diff --git a/hw/ppc/spapr_caps.c b/hw/ppc/spapr_caps.c
index 778bf32181..1675ebd45e 100644
--- a/hw/ppc/spapr_caps.c
+++ b/hw/ppc/spapr_caps.c
@@ -509,9 +509,14 @@ static void cap_fwnmi_mce_apply(SpaprMachineState *spapr, uint8_t val,
          * of software injected faults like duplicate SLBs).
          */
         warn_report("Firmware Assisted Non-Maskable Interrupts not supported in TCG");
-    } else if (kvm_enabled() && kvmppc_set_fwnmi()) {
-        error_setg(errp,
+    } else if (kvm_enabled()) {
+        if (!kvmppc_set_fwnmi()) {
+            /* Register ibm,nmi-register and ibm,nmi-interlock RTAS calls */
+            spapr_fwnmi_register();
+        } else {
+            error_setg(errp,
 "Firmware Assisted Non-Maskable Interrupts not supported by KVM, try cap-fwnmi-mce=off");
+        }
     }
 }
 
diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index 2c066a372d..0328b1f341 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -400,6 +400,55 @@ static void rtas_get_power_level(PowerPCCPU *cpu, SpaprMachineState *spapr,
     rtas_st(rets, 1, 100);
 }
 
+static void rtas_ibm_nmi_register(PowerPCCPU *cpu,
+                                  SpaprMachineState *spapr,
+                                  uint32_t token, uint32_t nargs,
+                                  target_ulong args,
+                                  uint32_t nret, target_ulong rets)
+{
+    hwaddr rtas_addr = spapr_get_rtas_addr();
+
+    if (!rtas_addr) {
+        rtas_st(rets, 0, RTAS_OUT_NOT_SUPPORTED);
+        return;
+    }
+
+    if (spapr_get_cap(spapr, SPAPR_CAP_FWNMI_MCE) == SPAPR_CAP_OFF) {
+        rtas_st(rets, 0, RTAS_OUT_NOT_SUPPORTED);
+        return;
+    }
+
+    spapr->guest_machine_check_addr = rtas_ld(args, 1);
+    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
+}
+
+static void rtas_ibm_nmi_interlock(PowerPCCPU *cpu,
+                                   SpaprMachineState *spapr,
+                                   uint32_t token, uint32_t nargs,
+                                   target_ulong args,
+                                   uint32_t nret, target_ulong rets)
+{
+    if (spapr->guest_machine_check_addr == -1) {
+        /* NMI register not called */
+        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
+        return;
+    }
+
+    if (spapr->mc_status != cpu->vcpu_id) {
+        /* The vCPU that hit the NMI should invoke "ibm,nmi-interlock" */
+        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
+        return;
+    }
+
+    /*
+     * vCPU issuing "ibm,nmi-interlock" is done with NMI handling,
+     * hence unset mc_status.
+     */
+    spapr->mc_status = -1;
+    qemu_cond_signal(&spapr->mc_delivery_cond);
+    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
+}
+
 static struct rtas_call {
     const char *name;
     spapr_rtas_fn fn;
@@ -503,6 +552,14 @@ hwaddr spapr_get_rtas_addr(void)
     return (hwaddr)fdt32_to_cpu(*rtas_data);
 }
 
+void spapr_fwnmi_register(void)
+{
+    spapr_rtas_register(RTAS_IBM_NMI_REGISTER, "ibm,nmi-register",
+                        rtas_ibm_nmi_register);
+    spapr_rtas_register(RTAS_IBM_NMI_INTERLOCK, "ibm,nmi-interlock",
+                        rtas_ibm_nmi_interlock);
+}
+
 static void core_rtas_register_types(void)
 {
     spapr_rtas_register(RTAS_DISPLAY_CHARACTER, "display-character",
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 8049f06d1c..fa280c956e 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -653,8 +653,10 @@ target_ulong spapr_hypercall(PowerPCCPU *cpu, target_ulong opcode,
 #define RTAS_IBM_REMOVE_PE_DMA_WINDOW           (RTAS_TOKEN_BASE + 0x28)
 #define RTAS_IBM_RESET_PE_DMA_WINDOW            (RTAS_TOKEN_BASE + 0x29)
 #define RTAS_IBM_SUSPEND_ME                     (RTAS_TOKEN_BASE + 0x2A)
+#define RTAS_IBM_NMI_REGISTER                   (RTAS_TOKEN_BASE + 0x2B)
+#define RTAS_IBM_NMI_INTERLOCK                  (RTAS_TOKEN_BASE + 0x2C)
 
-#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2B)
+#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2D)
 
 /* RTAS ibm,get-system-parameter token values */
 #define RTAS_SYSPARM_SPLPAR_CHARACTERISTICS      20
@@ -906,4 +908,5 @@ void spapr_check_pagesize(SpaprMachineState *spapr, hwaddr pagesize,
 
 void spapr_set_all_lpcrs(target_ulong value, target_ulong mask);
 hwaddr spapr_get_rtas_addr(void);
+void spapr_fwnmi_register(void);
 #endif /* HW_SPAPR_H */
-- 
2.17.2