[Qemu-devel] [PULL 38/38] spapr/irq: add KVM support to the 'dual' machine

[David Gibson]

From: Cédric Le Goater <address@hidden>

The interrupt mode is chosen by the CAS negotiation process and
activated after a reset to take into account the required changes in
the machine. This brings new constraints on how the associated KVM IRQ
device is initialized.

Currently, each model takes care of the initialization of the KVM
device in their realize method but this is not possible anymore as the
initialization needs to be done globaly when the interrupt mode is
known, i.e. when machine is reseted. It also means that we need a way
to delete a KVM device when another mode is chosen.

Also, to support migration, the QEMU objects holding the state to
transfer should always be available but not necessarily activated.

The overall approach of this proposal is to initialize both interrupt
mode at the QEMU level to keep the IRQ number space in sync and to
allow switching from one mode to another. For the KVM side of things,
the whole initialization of the KVM device, sources and presenters, is
grouped in a single routine. The XICS and XIVE sPAPR IRQ reset
handlers are modified accordingly to handle the init and the delete
sequences of the KVM device.

Signed-off-by: Cédric Le Goater <address@hidden>
Reviewed-by: David Gibson <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: David Gibson <address@hidden>
---
 hw/intc/spapr_xive_kvm.c | 29 +++++++++++++++++++-
 hw/intc/xics_kvm.c       | 31 +++++++++++++++++++++
 hw/intc/xive.c           |  4 ---
 hw/ppc/spapr_irq.c       | 58 ++++++++++++++++++++++++++--------------
 include/hw/ppc/xive.h    |  1 -
 5 files changed, 97 insertions(+), 26 deletions(-)

diff --git a/hw/intc/spapr_xive_kvm.c b/hw/intc/spapr_xive_kvm.c
index 078d18d775..ec170b3045 100644
--- a/hw/intc/spapr_xive_kvm.c
+++ b/hw/intc/spapr_xive_kvm.c
@@ -246,7 +246,7 @@ void kvmppc_xive_source_reset_one(XiveSource *xsrc, int 
srcno, Error **errp)
                       true, errp);
 }
 
-void kvmppc_xive_source_reset(XiveSource *xsrc, Error **errp)
+static void kvmppc_xive_source_reset(XiveSource *xsrc, Error **errp)
 {
     int i;
 
@@ -697,6 +697,15 @@ void kvmppc_xive_connect(SpaprXive *xive, Error **errp)
     Error *local_err = NULL;
     size_t esb_len = (1ull << xsrc->esb_shift) * xsrc->nr_irqs;
     size_t tima_len = 4ull << TM_SHIFT;
+    CPUState *cs;
+
+    /*
+     * The KVM XIVE device already in use. This is the case when
+     * rebooting under the XIVE-only interrupt mode.
+     */
+    if (xive->fd != -1) {
+        return;
+    }
 
     if (!kvmppc_has_cap_xive()) {
         error_setg(errp, "IRQ_XIVE capability must be present for KVM");
@@ -745,6 +754,24 @@ void kvmppc_xive_connect(SpaprXive *xive, Error **errp)
     xive->change = qemu_add_vm_change_state_handler(
         kvmppc_xive_change_state_handler, xive);
 
+    /* Connect the presenters to the initial VCPUs of the machine */
+    CPU_FOREACH(cs) {
+        PowerPCCPU *cpu = POWERPC_CPU(cs);
+
+        kvmppc_xive_cpu_connect(spapr_cpu_state(cpu)->tctx, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
+    }
+
+    /* Update the KVM sources */
+    kvmppc_xive_source_reset(xsrc, &local_err);
+    if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+    }
+
     kvm_kernel_irqchip = true;
     kvm_msi_via_irqfd_allowed = true;
     kvm_gsi_direct_mapping = true;
diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
index 12bd5190cf..5ba5b77561 100644
--- a/hw/intc/xics_kvm.c
+++ b/hw/intc/xics_kvm.c
@@ -33,6 +33,7 @@
 #include "trace.h"
 #include "sysemu/kvm.h"
 #include "hw/ppc/spapr.h"
+#include "hw/ppc/spapr_cpu_core.h"
 #include "hw/ppc/xics.h"
 #include "hw/ppc/xics_spapr.h"
 #include "kvm_ppc.h"
@@ -342,6 +343,16 @@ static void rtas_dummy(PowerPCCPU *cpu, SpaprMachineState 
*spapr,
 int xics_kvm_init(SpaprMachineState *spapr, Error **errp)
 {
     int rc;
+    CPUState *cs;
+    Error *local_err = NULL;
+
+    /*
+     * The KVM XICS device already in use. This is the case when
+     * rebooting under the XICS-only interrupt mode.
+     */
+    if (kernel_xics_fd != -1) {
+        return 0;
+    }
 
     if (!kvm_enabled() || !kvm_check_extension(kvm_state, KVM_CAP_IRQ_XICS)) {
         error_setg(errp,
@@ -390,6 +401,26 @@ int xics_kvm_init(SpaprMachineState *spapr, Error **errp)
     kvm_msi_via_irqfd_allowed = true;
     kvm_gsi_direct_mapping = true;
 
+    /* Create the presenters */
+    CPU_FOREACH(cs) {
+        PowerPCCPU *cpu = POWERPC_CPU(cs);
+
+        icp_kvm_realize(DEVICE(spapr_cpu_state(cpu)->icp), &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            goto fail;
+        }
+    }
+
+    /* Update the KVM sources */
+    ics_set_kvm_state(spapr->ics);
+
+    /* Connect the presenters to the initial VCPUs of the machine */
+    CPU_FOREACH(cs) {
+        PowerPCCPU *cpu = POWERPC_CPU(cs);
+        icp_set_kvm_state(spapr_cpu_state(cpu)->icp);
+    }
+
     return 0;
 
 fail:
diff --git a/hw/intc/xive.c b/hw/intc/xive.c
index b5ebb33527..0c74e47aa4 100644
--- a/hw/intc/xive.c
+++ b/hw/intc/xive.c
@@ -993,10 +993,6 @@ static void xive_source_reset(void *dev)
 
     /* PQs are initialized to 0b01 (Q=1) which corresponds to "ints off" */
     memset(xsrc->status, XIVE_ESB_OFF, xsrc->nr_irqs);
-
-    if (kvm_irqchip_in_kernel()) {
-        kvmppc_xive_source_reset(xsrc, &error_fatal);
-    }
 }
 
 static void xive_source_realize(DeviceState *dev, Error **errp)
diff --git a/hw/ppc/spapr_irq.c b/hw/ppc/spapr_irq.c
index d1e87577fb..3156daf093 100644
--- a/hw/ppc/spapr_irq.c
+++ b/hw/ppc/spapr_irq.c
@@ -102,12 +102,6 @@ static void spapr_irq_init_xics(SpaprMachineState *spapr, 
int nr_irqs,
     Object *obj;
     Error *local_err = NULL;
 
-    spapr_irq_init_device(spapr, &spapr_irq_xics, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
-        return;
-    }
-
     obj = object_new(TYPE_ICS_SIMPLE);
     object_property_add_child(OBJECT(spapr), "ics", obj, &error_abort);
     object_property_add_const_link(obj, ICS_PROP_XICS, OBJECT(spapr),
@@ -226,7 +220,13 @@ static void spapr_irq_set_irq_xics(void *opaque, int 
srcno, int val)
 
 static void spapr_irq_reset_xics(SpaprMachineState *spapr, Error **errp)
 {
-    /* TODO: create the KVM XICS device */
+    Error *local_err = NULL;
+
+    spapr_irq_init_device(spapr, &spapr_irq_xics, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
 }
 
 static const char *spapr_irq_get_nodename_xics(SpaprMachineState *spapr)
@@ -279,7 +279,6 @@ static void spapr_irq_init_xive(SpaprMachineState *spapr, 
int nr_irqs,
     uint32_t nr_servers = spapr_max_server_number(spapr);
     DeviceState *dev;
     int i;
-    Error *local_err = NULL;
 
     dev = qdev_create(NULL, TYPE_SPAPR_XIVE);
     qdev_prop_set_uint32(dev, "nr-irqs", nr_irqs);
@@ -297,12 +296,6 @@ static void spapr_irq_init_xive(SpaprMachineState *spapr, 
int nr_irqs,
     }
 
     spapr_xive_hcall_init(spapr);
-
-    spapr_irq_init_device(spapr, &spapr_irq_xive, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
-        return;
-    }
 }
 
 static int spapr_irq_claim_xive(SpaprMachineState *spapr, int irq, bool lsi,
@@ -382,6 +375,7 @@ static int spapr_irq_post_load_xive(SpaprMachineState 
*spapr, int version_id)
 static void spapr_irq_reset_xive(SpaprMachineState *spapr, Error **errp)
 {
     CPUState *cs;
+    Error *local_err = NULL;
 
     CPU_FOREACH(cs) {
         PowerPCCPU *cpu = POWERPC_CPU(cs);
@@ -390,6 +384,12 @@ static void spapr_irq_reset_xive(SpaprMachineState *spapr, 
Error **errp)
         spapr_xive_set_tctx_os_cam(spapr_cpu_state(cpu)->tctx);
     }
 
+    spapr_irq_init_device(spapr, &spapr_irq_xive, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
     /* Activate the XIVE MMIOs */
     spapr_xive_mmio_set_enabled(spapr->xive, true);
 }
@@ -472,14 +472,8 @@ static SpaprIrq *spapr_irq_current(SpaprMachineState 
*spapr)
 static void spapr_irq_init_dual(SpaprMachineState *spapr, int nr_irqs,
                                 Error **errp)
 {
-    MachineState *machine = MACHINE(spapr);
     Error *local_err = NULL;
 
-    if (kvm_enabled() && machine_kernel_irqchip_allowed(machine)) {
-        error_setg(errp, "No KVM support for the 'dual' machine");
-        return;
-    }
-
     spapr_irq_xics.init(spapr, spapr_irq_xics.nr_irqs, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
@@ -558,6 +552,9 @@ static int spapr_irq_post_load_dual(SpaprMachineState 
*spapr, int version_id)
      * defaults to XICS at startup.
      */
     if (spapr_ovec_test(spapr->ov5_cas, OV5_XIVE_EXPLOIT)) {
+        if (kvm_irqchip_in_kernel()) {
+            xics_kvm_disconnect(spapr, &error_fatal);
+        }
         spapr_irq_xive.reset(spapr, &error_fatal);
     }
 
@@ -566,12 +563,30 @@ static int spapr_irq_post_load_dual(SpaprMachineState 
*spapr, int version_id)
 
 static void spapr_irq_reset_dual(SpaprMachineState *spapr, Error **errp)
 {
+    Error *local_err = NULL;
+
     /*
      * Deactivate the XIVE MMIOs. The XIVE backend will reenable them
      * if selected.
      */
     spapr_xive_mmio_set_enabled(spapr->xive, false);
 
+    /* Destroy all KVM devices */
+    if (kvm_irqchip_in_kernel()) {
+        xics_kvm_disconnect(spapr, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            error_prepend(errp, "KVM XICS disconnect failed: ");
+            return;
+        }
+        kvmppc_xive_disconnect(spapr->xive, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            error_prepend(errp, "KVM XIVE disconnect failed: ");
+            return;
+        }
+    }
+
     spapr_irq_current(spapr)->reset(spapr, errp);
 }
 
@@ -809,6 +824,9 @@ SpaprIrq spapr_irq_xics_legacy = {
     .dt_populate = spapr_dt_xics,
     .cpu_intc_create = spapr_irq_cpu_intc_create_xics,
     .post_load   = spapr_irq_post_load_xics,
+    .reset       = spapr_irq_reset_xics,
     .set_irq     = spapr_irq_set_irq_xics,
     .get_nodename = spapr_irq_get_nodename_xics,
+    .init_emu    = spapr_irq_init_emu_xics,
+    .init_kvm    = spapr_irq_init_kvm_xics,
 };
diff --git a/include/hw/ppc/xive.h b/include/hw/ppc/xive.h
index edb8937f17..d872f96d1a 100644
--- a/include/hw/ppc/xive.h
+++ b/include/hw/ppc/xive.h
@@ -432,7 +432,6 @@ static inline uint32_t xive_nvt_cam_line(uint8_t nvt_blk, 
uint32_t nvt_idx)
  */
 
 void kvmppc_xive_source_reset_one(XiveSource *xsrc, int srcno, Error **errp);
-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);
-- 
2.21.0