[Qemu-devel] [patch-for-4.2 PATCH v11 2/6] ppc: spapr: Introduce FWNMI capability

[Aravinda Prasad <aravinda@linux.vnet.ibm.com>]

Introduce the KVM capability KVM_CAP_PPC_FWNMI so that
the KVM causes guest exit with NMI as exit reason
when it encounters a machine check exception on the
address belonging to a guest. Without this capability
enabled, KVM redirects machine check exceptions to
guest's 0x200 vector.

This patch also introduces fwnmi-mce capability to
deal with the case when a guest with the
KVM_CAP_PPC_FWNMI capability enabled is attempted
to migrate to a host that does not support this
capability.

Signed-off-by: Aravinda Prasad <aravinda@linux.vnet.ibm.com>
---
 hw/ppc/spapr.c         |    1 +
 hw/ppc/spapr_caps.c    |   29 +++++++++++++++++++++++++++++
 include/hw/ppc/spapr.h |    4 +++-
 target/ppc/kvm.c       |   22 ++++++++++++++++++++++
 target/ppc/kvm_ppc.h   |   11 +++++++++++
 5 files changed, 66 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 855e9fb..07714cb 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -4463,6 +4463,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
     smc->default_caps.caps[SPAPR_CAP_NESTED_KVM_HV] = SPAPR_CAP_OFF;
     smc->default_caps.caps[SPAPR_CAP_LARGE_DECREMENTER] = SPAPR_CAP_ON;
     smc->default_caps.caps[SPAPR_CAP_CCF_ASSIST] = SPAPR_CAP_OFF;
+    smc->default_caps.caps[SPAPR_CAP_FWNMI_MCE] = SPAPR_CAP_OFF;
     spapr_caps_add_properties(smc, &error_abort);
     smc->irq = &spapr_irq_dual;
     smc->dr_phb_enabled = true;
diff --git a/hw/ppc/spapr_caps.c b/hw/ppc/spapr_caps.c
index 0263c78..5448123 100644
--- a/hw/ppc/spapr_caps.c
+++ b/hw/ppc/spapr_caps.c
@@ -481,6 +481,25 @@ static void cap_ccf_assist_apply(SpaprMachineState *spapr, uint8_t val,
     }
 }
 
+static void cap_fwnmi_mce_apply(SpaprMachineState *spapr, uint8_t val,
+                                Error **errp)
+{
+    if (!val) {
+        return; /* Disabled by default */
+    }
+
+    if (tcg_enabled()) {
+        /*
+         * TCG support may not be correct in some conditions (e.g., in case
+         * of software injected faults like duplicate SLBs).
+         */
+        warn_report("Firmware Assisted Non-Maskable Interrupts not supported in TCG");
+    } else if (kvm_enabled() && !kvmppc_has_cap_ppc_fwnmi()) {
+        error_setg(errp,
+"Firmware Assisted Non-Maskable Interrupts not supported by KVM, try cap-fwnmi-mce=off");
+    }
+}
+
 SpaprCapabilityInfo capability_table[SPAPR_CAP_NUM] = {
     [SPAPR_CAP_HTM] = {
         .name = "htm",
@@ -580,6 +599,15 @@ SpaprCapabilityInfo capability_table[SPAPR_CAP_NUM] = {
         .type = "bool",
         .apply = cap_ccf_assist_apply,
     },
+    [SPAPR_CAP_FWNMI_MCE] = {
+        .name = "fwnmi-mce",
+        .description = "Handle fwnmi machine check exceptions",
+        .index = SPAPR_CAP_FWNMI_MCE,
+        .get = spapr_cap_get_bool,
+        .set = spapr_cap_set_bool,
+        .type = "bool",
+        .apply = cap_fwnmi_mce_apply,
+    },
 };
 
 static SpaprCapabilities default_caps_with_cpu(SpaprMachineState *spapr,
@@ -719,6 +747,7 @@ SPAPR_CAP_MIG_STATE(hpt_maxpagesize, SPAPR_CAP_HPT_MAXPAGESIZE);
 SPAPR_CAP_MIG_STATE(nested_kvm_hv, SPAPR_CAP_NESTED_KVM_HV);
 SPAPR_CAP_MIG_STATE(large_decr, SPAPR_CAP_LARGE_DECREMENTER);
 SPAPR_CAP_MIG_STATE(ccf_assist, SPAPR_CAP_CCF_ASSIST);
+SPAPR_CAP_MIG_STATE(fwnmi, SPAPR_CAP_FWNMI_MCE);
 
 void spapr_caps_init(SpaprMachineState *spapr)
 {
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index fa7c380..01c106f 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -79,8 +79,10 @@ typedef enum {
 #define SPAPR_CAP_LARGE_DECREMENTER     0x08
 /* Count Cache Flush Assist HW Instruction */
 #define SPAPR_CAP_CCF_ASSIST            0x09
+/* FWNMI machine check handling */
+#define SPAPR_CAP_FWNMI_MCE             0x0A
 /* Num Caps */
-#define SPAPR_CAP_NUM                   (SPAPR_CAP_CCF_ASSIST + 1)
+#define SPAPR_CAP_NUM                   (SPAPR_CAP_FWNMI_MCE + 1)
 
 /*
  * Capability Values
diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
index 5ab5e6c..c922bcb 100644
--- a/target/ppc/kvm.c
+++ b/target/ppc/kvm.c
@@ -83,6 +83,7 @@ static int cap_ppc_safe_indirect_branch;
 static int cap_ppc_count_cache_flush_assist;
 static int cap_ppc_nested_kvm_hv;
 static int cap_large_decr;
+static int cap_ppc_fwnmi;
 
 static uint32_t debug_inst_opcode;
 
@@ -2053,6 +2054,22 @@ void kvmppc_set_mpic_proxy(PowerPCCPU *cpu, int mpic_proxy)
     }
 }
 
+int kvmppc_set_fwnmi(void)
+{
+    PowerPCCPU *cpu = POWERPC_CPU(first_cpu);
+    CPUState *cs = CPU(cpu);
+    int ret;
+
+    ret = kvm_vcpu_enable_cap(cs, KVM_CAP_PPC_FWNMI, 0);
+    if (ret) {
+        error_report("This KVM version does not support FWNMI");
+        return ret;
+    }
+
+    cap_ppc_fwnmi = 1;
+    return ret;
+}
+
 int kvmppc_smt_threads(void)
 {
     return cap_ppc_smt ? cap_ppc_smt : 1;
@@ -2353,6 +2370,11 @@ bool kvmppc_has_cap_mmu_hash_v3(void)
     return cap_mmu_hash_v3;
 }
 
+bool kvmppc_has_cap_ppc_fwnmi(void)
+{
+    return cap_ppc_fwnmi;
+}
+
 static bool kvmppc_power8_host(void)
 {
     bool ret = false;
diff --git a/target/ppc/kvm_ppc.h b/target/ppc/kvm_ppc.h
index 98bd7d5..2990898 100644
--- a/target/ppc/kvm_ppc.h
+++ b/target/ppc/kvm_ppc.h
@@ -27,6 +27,8 @@ void kvmppc_enable_h_page_init(void);
 void kvmppc_set_papr(PowerPCCPU *cpu);
 int kvmppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr);
 void kvmppc_set_mpic_proxy(PowerPCCPU *cpu, int mpic_proxy);
+int kvmppc_set_fwnmi(void);
+bool kvmppc_has_cap_ppc_fwnmi(void);
 int kvmppc_smt_threads(void);
 void kvmppc_hint_smt_possible(Error **errp);
 int kvmppc_set_smt_threads(int smt);
@@ -159,6 +161,15 @@ static inline void kvmppc_set_mpic_proxy(PowerPCCPU *cpu, int mpic_proxy)
 {
 }
 
+static inline int kvmppc_set_fwnmi(void)
+{
+}
+
+static inline bool kvmppc_has_cap_ppc_fwnmi(void)
+{
+    return false;
+}
+
 static inline int kvmppc_smt_threads(void)
 {
     return 1;