[Qemu-devel] [PATCH 05/13] spapr/xive: add migration support for KVM

[Cédric Le Goater]

When the VM is stopped, the VM state handler stabilizes the XIVE IC
and marks the EQ pages dirty. These are then transferred to destination
before the transfer of the device vmstates starts.

The sPAPRXive interrupt controller model captures the XIVE internal
tables, EAT and ENDT and the XiveTCTX model does the same for the
thread interrupt context registers.

At restart, the sPAPRXive 'post_load' method restores all the XIVE
states. It is called by the sPAPR machine 'post_load' method, when all
XIVE states have been transferred and loaded.

Finally, the source states are restored in the VM change state handler
when the machine reaches the running state.

Signed-off-by: Cédric Le Goater <address@hidden>
---
 include/hw/ppc/spapr_xive.h |   5 +
 include/hw/ppc/xive.h       |   1 +
 hw/intc/spapr_xive.c        |  34 +++++++
 hw/intc/spapr_xive_kvm.c    | 187 +++++++++++++++++++++++++++++++++++-
 hw/intc/xive.c              |  17 ++++
 hw/ppc/spapr_irq.c          |   2 +-
 6 files changed, 244 insertions(+), 2 deletions(-)

diff --git a/include/hw/ppc/spapr_xive.h b/include/hw/ppc/spapr_xive.h
index 8815ed5aa372..52804516e909 100644
--- a/include/hw/ppc/spapr_xive.h
+++ b/include/hw/ppc/spapr_xive.h
@@ -46,6 +46,7 @@ bool spapr_xive_irq_claim(sPAPRXive *xive, uint32_t lisn, 
bool lsi);
 bool spapr_xive_irq_free(sPAPRXive *xive, uint32_t lisn);
 void spapr_xive_pic_print_info(sPAPRXive *xive, Monitor *mon);
 bool spapr_xive_priority_is_reserved(uint8_t priority);
+int spapr_xive_post_load(sPAPRXive *xive, int version_id);
 
 void spapr_xive_cpu_to_nvt(PowerPCCPU *cpu,
                            uint8_t *out_nvt_blk, uint32_t *out_nvt_idx);
@@ -53,6 +54,8 @@ void spapr_xive_cpu_to_end(PowerPCCPU *cpu, uint8_t prio,
                            uint8_t *out_end_blk, uint32_t *out_end_idx);
 int spapr_xive_target_to_end(uint32_t target, uint8_t prio,
                              uint8_t *out_end_blk, uint32_t *out_end_idx);
+int spapr_xive_end_to_target(uint8_t end_blk, uint32_t end_idx,
+                             uint32_t *out_server, uint8_t *out_prio);
 
 typedef struct sPAPRMachineState sPAPRMachineState;
 
@@ -68,5 +71,7 @@ void spapr_xive_map_mmio(sPAPRXive *xive);
  */
 void kvmppc_xive_connect(sPAPRXive *xive, Error **errp);
 void kvmppc_xive_synchronize_state(sPAPRXive *xive, Error **errp);
+int kvmppc_xive_pre_save(sPAPRXive *xive);
+int kvmppc_xive_post_load(sPAPRXive *xive, int version_id);
 
 #endif /* PPC_SPAPR_XIVE_H */
diff --git a/include/hw/ppc/xive.h b/include/hw/ppc/xive.h
index 2e48d75a22e0..8aa314f93ffd 100644
--- a/include/hw/ppc/xive.h
+++ b/include/hw/ppc/xive.h
@@ -443,5 +443,6 @@ void kvmppc_xive_source_reset(XiveSource *xsrc, Error 
**errp);
 void kvmppc_xive_source_set_irq(void *opaque, int srcno, int val);
 void kvmppc_xive_cpu_connect(XiveTCTX *tctx, Error **errp);
 void kvmppc_xive_cpu_synchronize_state(XiveTCTX *tctx, Error **errp);
+void kvmppc_xive_cpu_get_state(XiveTCTX *tctx, Error **errp);
 
 #endif /* PPC_XIVE_H */
diff --git a/hw/intc/spapr_xive.c b/hw/intc/spapr_xive.c
index 50dd66707968..21f3c1ef0901 100644
--- a/hw/intc/spapr_xive.c
+++ b/hw/intc/spapr_xive.c
@@ -85,6 +85,19 @@ static int spapr_xive_target_to_nvt(uint32_t target,
  * sPAPR END indexing uses a simple mapping of the CPU vcpu_id, 8
  * priorities per CPU
  */
+int spapr_xive_end_to_target(uint8_t end_blk, uint32_t end_idx,
+                             uint32_t *out_server, uint8_t *out_prio)
+{
+    if (out_server) {
+        *out_server = end_idx >> 3;
+    }
+
+    if (out_prio) {
+        *out_prio = end_idx & 0x7;
+    }
+    return 0;
+}
+
 void spapr_xive_cpu_to_end(PowerPCCPU *cpu, uint8_t prio,
                            uint8_t *out_end_blk, uint32_t *out_end_idx)
 {
@@ -438,10 +451,31 @@ static const VMStateDescription vmstate_spapr_xive_eas = {
     },
 };
 
+static int vmstate_spapr_xive_pre_save(void *opaque)
+{
+    if (kvmppc_xive_enabled()) {
+        return kvmppc_xive_pre_save(SPAPR_XIVE(opaque));
+    }
+
+    return 0;
+}
+
+/* Called by the sPAPR machine 'post_load' method */
+int spapr_xive_post_load(sPAPRXive *xive, int version_id)
+{
+    if (kvmppc_xive_enabled()) {
+        return kvmppc_xive_post_load(xive, version_id);
+    }
+
+    return 0;
+}
+
 static const VMStateDescription vmstate_spapr_xive = {
     .name = TYPE_SPAPR_XIVE,
     .version_id = 1,
     .minimum_version_id = 1,
+    .pre_save = vmstate_spapr_xive_pre_save,
+    .post_load = NULL, /* handled at the machine level */
     .fields = (VMStateField[]) {
         VMSTATE_UINT32_EQUAL(nr_irqs, sPAPRXive, NULL),
         VMSTATE_STRUCT_VARRAY_POINTER_UINT32(eat, sPAPRXive, nr_irqs,
diff --git a/hw/intc/spapr_xive_kvm.c b/hw/intc/spapr_xive_kvm.c
index c7639ffe7758..fe58a9ee32d3 100644
--- a/hw/intc/spapr_xive_kvm.c
+++ b/hw/intc/spapr_xive_kvm.c
@@ -60,7 +60,30 @@ static void kvm_cpu_enable(CPUState *cs)
 /*
  * XIVE Thread Interrupt Management context (KVM)
  */
-static void kvmppc_xive_cpu_get_state(XiveTCTX *tctx, Error **errp)
+
+static void kvmppc_xive_cpu_set_state(XiveTCTX *tctx, Error **errp)
+{
+    uint64_t state[4];
+    int ret;
+
+    /* word0 and word1 of the OS ring. */
+    state[0] = *((uint64_t *) &tctx->regs[TM_QW1_OS]);
+
+    /*
+     * OS CAM line. Used by KVM to print out the VP identifier. This
+     * is for debug only.
+     */
+    state[1] = *((uint64_t *) &tctx->regs[TM_QW1_OS + TM_WORD2]);
+
+    ret = kvm_set_one_reg(tctx->cs, KVM_REG_PPC_NVT_STATE, state);
+    if (ret != 0) {
+        error_setg_errno(errp, errno,
+                         "XIVE: could not restore KVM state of CPU %ld",
+                         kvm_arch_vcpu_id(tctx->cs));
+    }
+}
+
+void kvmppc_xive_cpu_get_state(XiveTCTX *tctx, Error **errp)
 {
     uint64_t state[4] = { 0 };
     int ret;
@@ -228,6 +251,58 @@ void kvmppc_xive_source_set_irq(void *opaque, int srcno, 
int val)
 /*
  * sPAPR XIVE interrupt controller (KVM)
  */
+static int kvmppc_xive_set_eq_state(sPAPRXive *xive, CPUState *cs, Error 
**errp)
+{
+    unsigned long vcpu_id = kvm_arch_vcpu_id(cs);
+    int ret;
+    int i;
+
+    for (i = 0; i < XIVE_PRIORITY_MAX + 1; i++) {
+        Error *local_err = NULL;
+        XiveEND *end;
+        uint8_t end_blk;
+        uint32_t end_idx;
+        struct kvm_ppc_xive_eq kvm_eq = { 0 };
+        uint64_t kvm_eq_idx;
+
+        if (spapr_xive_priority_is_reserved(i)) {
+            continue;
+        }
+
+        spapr_xive_cpu_to_end(POWERPC_CPU(cs), i, &end_blk, &end_idx);
+
+        assert(end_idx < xive->nr_ends);
+        end = &xive->endt[end_idx];
+
+        if (!xive_end_is_valid(end)) {
+            continue;
+        }
+
+        /* Build the KVM state from the local END structure */
+        kvm_eq.flags   = KVM_XIVE_EQ_FLAG_ALWAYS_NOTIFY;
+        kvm_eq.qsize   = xive_get_field32(END_W0_QSIZE, end->w0) + 12;
+        kvm_eq.qpage   = (uint64_t) be32_to_cpu(end->w2 & 0x0fffffff) << 32 |
+            be32_to_cpu(end->w3);
+        kvm_eq.qtoggle = xive_get_field32(END_W1_GENERATION, end->w1);
+        kvm_eq.qindex  = xive_get_field32(END_W1_PAGE_OFF, end->w1);
+
+        /* Encode the tuple (server, prio) as a KVM EQ index */
+        kvm_eq_idx = i << KVM_XIVE_EQ_PRIORITY_SHIFT &
+            KVM_XIVE_EQ_PRIORITY_MASK;
+        kvm_eq_idx |= vcpu_id << KVM_XIVE_EQ_SERVER_SHIFT &
+            KVM_XIVE_EQ_SERVER_MASK;
+
+        ret = kvm_device_access(xive->fd, KVM_DEV_XIVE_GRP_EQ, kvm_eq_idx,
+                                &kvm_eq, true, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return ret;
+        }
+    }
+
+    return 0;
+}
+
 static int kvmppc_xive_get_eq_state(sPAPRXive *xive, CPUState *cs, Error 
**errp)
 {
     unsigned long vcpu_id = kvm_arch_vcpu_id(cs);
@@ -298,6 +373,48 @@ static int kvmppc_xive_get_eq_state(sPAPRXive *xive, 
CPUState *cs, Error **errp)
     return 0;
 }
 
+static void kvmppc_xive_set_eas_state(sPAPRXive *xive, Error **errp)
+{
+    XiveSource *xsrc = &xive->source;
+    int i;
+
+    for (i = 0; i < xsrc->nr_irqs; i++) {
+        XiveEAS *eas = &xive->eat[i];
+        uint32_t end_idx;
+        uint32_t end_blk;
+        uint32_t eisn;
+        uint8_t priority;
+        uint32_t server;
+        uint64_t kvm_eas;
+        Error *local_err = NULL;
+
+        /* No need to set MASKED EAS, this is the default state after reset */
+        if (!xive_eas_is_valid(eas) || xive_eas_is_masked(eas)) {
+            continue;
+        }
+
+        end_idx = xive_get_field64(EAS_END_INDEX, eas->w);
+        end_blk = xive_get_field64(EAS_END_BLOCK, eas->w);
+        eisn = xive_get_field64(EAS_END_DATA, eas->w);
+
+        spapr_xive_end_to_target(end_blk, end_idx, &server, &priority);
+
+        kvm_eas = priority << KVM_XIVE_EAS_PRIORITY_SHIFT &
+            KVM_XIVE_EAS_PRIORITY_MASK;
+        kvm_eas |= server << KVM_XIVE_EAS_SERVER_SHIFT &
+            KVM_XIVE_EAS_SERVER_MASK;
+        kvm_eas |= ((uint64_t)eisn << KVM_XIVE_EAS_EISN_SHIFT) &
+            KVM_XIVE_EAS_EISN_MASK;
+
+        kvm_device_access(xive->fd, KVM_DEV_XIVE_GRP_EAS, i, &kvm_eas, true,
+                          &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
+    }
+}
+
 static void kvmppc_xive_get_eas_state(sPAPRXive *xive, Error **errp)
 {
     XiveSource *xsrc = &xive->source;
@@ -448,6 +565,74 @@ static void kvmppc_xive_change_state_handler(void *opaque, 
int running,
     }
 }
 
+int kvmppc_xive_pre_save(sPAPRXive *xive)
+{
+    Error *local_err = NULL;
+    CPUState *cs;
+
+    /* Grab the EAT */
+    kvmppc_xive_get_eas_state(xive, &local_err);
+    if (local_err) {
+        error_report_err(local_err);
+        return -1;
+    }
+
+    /*
+     * Grab the ENDT. The EQ index and the toggle bit are what we want
+     * to capture.
+     */
+    CPU_FOREACH(cs) {
+        kvmppc_xive_get_eq_state(xive, cs, &local_err);
+        if (local_err) {
+            error_report_err(local_err);
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
+/*
+ * The sPAPRXive 'post_load' method is called by the sPAPR machine
+ * 'post_load' method, when all XIVE states have been transferred and
+ * loaded.
+ */
+int kvmppc_xive_post_load(sPAPRXive *xive, int version_id)
+{
+    Error *local_err = NULL;
+    CPUState *cs;
+
+    /* Restore the ENDT first. The targetting depends on it. */
+    CPU_FOREACH(cs) {
+        kvmppc_xive_set_eq_state(xive, cs, &local_err);
+        if (local_err) {
+            error_report_err(local_err);
+            return -1;
+        }
+    }
+
+    /* Restore the EAT */
+    kvmppc_xive_set_eas_state(xive, &local_err);
+    if (local_err) {
+        error_report_err(local_err);
+        return -1;
+    }
+
+    /* Restore the thread interrupt contexts */
+    CPU_FOREACH(cs) {
+        PowerPCCPU *cpu = POWERPC_CPU(cs);
+
+        kvmppc_xive_cpu_set_state(cpu->tctx, &local_err);
+        if (local_err) {
+            error_report_err(local_err);
+            return -1;
+        }
+    }
+
+    /* The source states will be restored when the machine starts running */
+    return 0;
+}
+
 void kvmppc_xive_synchronize_state(sPAPRXive *xive, Error **errp)
 {
     XiveSource *xsrc = &xive->source;
diff --git a/hw/intc/xive.c b/hw/intc/xive.c
index 596c29d8c826..c5c2fbc3f8bc 100644
--- a/hw/intc/xive.c
+++ b/hw/intc/xive.c
@@ -521,10 +521,27 @@ static void xive_tctx_unrealize(DeviceState *dev, Error 
**errp)
     qemu_unregister_reset(xive_tctx_reset, dev);
 }
 
+static int vmstate_xive_tctx_pre_save(void *opaque)
+{
+    Error *local_err = NULL;
+
+    if (kvmppc_xive_enabled()) {
+        kvmppc_xive_cpu_get_state(XIVE_TCTX(opaque), &local_err);
+        if (local_err) {
+            error_report_err(local_err);
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
 static const VMStateDescription vmstate_xive_tctx = {
     .name = TYPE_XIVE_TCTX,
     .version_id = 1,
     .minimum_version_id = 1,
+    .pre_save = vmstate_xive_tctx_pre_save,
+    .post_load = NULL, /* handled by the sPAPRxive model */
     .fields = (VMStateField[]) {
         VMSTATE_BUFFER(regs, XiveTCTX),
         VMSTATE_END_OF_LIST()
diff --git a/hw/ppc/spapr_irq.c b/hw/ppc/spapr_irq.c
index afbdabfa6543..233c97c5ecd9 100644
--- a/hw/ppc/spapr_irq.c
+++ b/hw/ppc/spapr_irq.c
@@ -363,7 +363,7 @@ static void 
spapr_irq_cpu_intc_create_xive(sPAPRMachineState *spapr,
 
 static int spapr_irq_post_load_xive(sPAPRMachineState *spapr, int version_id)
 {
-    return 0;
+    return spapr_xive_post_load(spapr->xive, version_id);
 }
 
 static void spapr_irq_reset_xive(sPAPRMachineState *spapr, Error **errp)
-- 
2.20.1