[Qemu-devel] [PATCH 10/13] spapr: introduce routines to delete the KVM IRQ device

["Cédric Le Goater" <clg@kaod.org>]

If a new interrupt mode is chosen by CAS, the machine generates a
reset to reconfigure. At this point, the connection with the previous
KVM device needs to be closed and a new connection needs to opened
with the KVM device operating the chosen interrupt mode.

New routines are introduced to destroy the XICS and the XIVE KVM
devices. They make use of a new KVM device ioctl which destroys the
device and also disconnects the IRQ presenters from the vCPUs.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 include/hw/ppc/spapr_xive.h |  1 +
 include/hw/ppc/xics.h       |  1 +
 hw/intc/spapr_xive_kvm.c    | 60 +++++++++++++++++++++++++++++++++++++
 hw/intc/xics_kvm.c          | 57 +++++++++++++++++++++++++++++++++++
 4 files changed, 119 insertions(+)

diff --git a/include/hw/ppc/spapr_xive.h b/include/hw/ppc/spapr_xive.h
index 52804516e909..f172fc20b650 100644
--- a/include/hw/ppc/spapr_xive.h
+++ b/include/hw/ppc/spapr_xive.h
@@ -70,6 +70,7 @@ void spapr_xive_map_mmio(sPAPRXive *xive);
  * KVM XIVE device helpers
  */
 void kvmppc_xive_connect(sPAPRXive *xive, Error **errp);
+void kvmppc_xive_disconnect(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);
diff --git a/include/hw/ppc/xics.h b/include/hw/ppc/xics.h
index 07508cbd217e..75d4effb5c5f 100644
--- a/include/hw/ppc/xics.h
+++ b/include/hw/ppc/xics.h
@@ -205,6 +205,7 @@ typedef struct sPAPRMachineState sPAPRMachineState;
 void spapr_dt_xics(sPAPRMachineState *spapr, uint32_t nr_servers, void *fdt,
                    uint32_t phandle);
 int xics_kvm_init(sPAPRMachineState *spapr, Error **errp);
+int xics_kvm_disconnect(sPAPRMachineState *spapr, Error **errp);
 void xics_spapr_init(sPAPRMachineState *spapr);
 
 Object *icp_create(Object *cpu, const char *type, XICSFabric *xi,
diff --git a/hw/intc/spapr_xive_kvm.c b/hw/intc/spapr_xive_kvm.c
index fe58a9ee32d3..93ea8e71047a 100644
--- a/hw/intc/spapr_xive_kvm.c
+++ b/hw/intc/spapr_xive_kvm.c
@@ -57,6 +57,16 @@ static void kvm_cpu_enable(CPUState *cs)
     QLIST_INSERT_HEAD(&kvm_enabled_cpus, enabled_cpu, node);
 }
 
+static void kvm_cpu_disable_all(void)
+{
+    KVMEnabledCPU *enabled_cpu, *next;
+
+    QLIST_FOREACH_SAFE(enabled_cpu, &kvm_enabled_cpus, node, next) {
+        QLIST_REMOVE(enabled_cpu, node);
+        g_free(enabled_cpu);
+    }
+}
+
 /*
  * XIVE Thread Interrupt Management context (KVM)
  */
@@ -769,3 +779,53 @@ void kvmppc_xive_connect(sPAPRXive *xive, Error **errp)
     /* Map all regions */
     spapr_xive_map_mmio(xive);
 }
+
+void kvmppc_xive_disconnect(sPAPRXive *xive, Error **errp)
+{
+    XiveSource *xsrc;
+    struct kvm_create_device xive_destroy_device = { 0 };
+    size_t esb_len;
+    int rc;
+
+    if (!kvm_enabled() || !kvmppc_has_cap_xive()) {
+        error_setg(errp, "IRQ_XIVE capability must be present for KVM");
+        return;
+    }
+
+    /* The KVM XIVE device is not in use */
+    if (!xive || xive->fd == -1) {
+        return;
+    }
+
+    /* Clear the KVM mapping */
+    xsrc = &xive->source;
+    esb_len = (1ull << xsrc->esb_shift) * xsrc->nr_irqs;
+
+    sysbus_mmio_unmap(SYS_BUS_DEVICE(xive), 0);
+    munmap(xsrc->esb_mmap, esb_len);
+
+    sysbus_mmio_unmap(SYS_BUS_DEVICE(xive), 1);
+
+    sysbus_mmio_unmap(SYS_BUS_DEVICE(xive), 2);
+    munmap(xive->tm_mmap, 4ull << TM_SHIFT);
+
+    /* Destroy the KVM device. This also clears the VCPU presenters */
+    xive_destroy_device.fd = xive->fd;
+    xive_destroy_device.type = KVM_DEV_TYPE_XIVE;
+    rc = kvm_vm_ioctl(kvm_state, KVM_DESTROY_DEVICE, &xive_destroy_device);
+    if (rc < 0) {
+        error_setg_errno(errp, -rc, "Error on KVM_DESTROY_DEVICE for XIVE");
+    }
+    close(xive->fd);
+    xive->fd = -1;
+
+    kvm_kernel_irqchip = false;
+    kvm_msi_via_irqfd_allowed = false;
+    kvm_gsi_direct_mapping = false;
+
+    /* Clear the local list of presenter (hotplug) */
+    kvm_cpu_disable_all();
+
+    /* VM Change state handler is not needed anymore */
+    qemu_del_vm_change_state_handler(xive->change);
+}
diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
index 2426e5b2f4ed..da6a00bc88cc 100644
--- a/hw/intc/xics_kvm.c
+++ b/hw/intc/xics_kvm.c
@@ -50,6 +50,16 @@ typedef struct KVMEnabledICP {
 static QLIST_HEAD(, KVMEnabledICP)
     kvm_enabled_icps = QLIST_HEAD_INITIALIZER(&kvm_enabled_icps);
 
+static void kvm_disable_icps(void)
+{
+    KVMEnabledICP *enabled_icp, *next;
+
+    QLIST_FOREACH_SAFE(enabled_icp, &kvm_enabled_icps, node, next) {
+        QLIST_REMOVE(enabled_icp, node);
+        g_free(enabled_icp);
+    }
+}
+
 /*
  * ICP-KVM
  */
@@ -455,6 +465,53 @@ fail:
     return -1;
 }
 
+int xics_kvm_disconnect(sPAPRMachineState *spapr, Error **errp)
+{
+    int rc;
+    struct kvm_create_device xics_create_device = {
+        .fd = kernel_xics_fd,
+        .type = KVM_DEV_TYPE_XICS,
+        .flags = 0,
+    };
+
+    /* The KVM XICS device is not in use */
+    if (kernel_xics_fd == -1) {
+        return 0;
+    }
+
+    if (!kvm_enabled() || !kvm_check_extension(kvm_state, KVM_CAP_IRQ_XICS)) {
+        error_setg(errp,
+                   "KVM and IRQ_XICS capability must be present for KVM XICS device");
+        return -1;
+    }
+
+    rc = kvm_vm_ioctl(kvm_state, KVM_DESTROY_DEVICE, &xics_create_device);
+    if (rc < 0) {
+        error_setg_errno(errp, -rc, "Error on KVM_DESTROY_DEVICE for XICS");
+    }
+    close(kernel_xics_fd);
+    kernel_xics_fd = -1;
+
+    spapr_rtas_register(RTAS_IBM_SET_XIVE, NULL, 0);
+    spapr_rtas_register(RTAS_IBM_GET_XIVE, NULL, 0);
+    spapr_rtas_register(RTAS_IBM_INT_OFF, NULL, 0);
+    spapr_rtas_register(RTAS_IBM_INT_ON, NULL, 0);
+
+    kvmppc_define_rtas_kernel_token(0, "ibm,set-xive");
+    kvmppc_define_rtas_kernel_token(0, "ibm,get-xive");
+    kvmppc_define_rtas_kernel_token(0, "ibm,int-on");
+    kvmppc_define_rtas_kernel_token(0, "ibm,int-off");
+
+    kvm_kernel_irqchip = false;
+    kvm_msi_via_irqfd_allowed = false;
+    kvm_gsi_direct_mapping = false;
+
+    /* Clear the presenter from the VCPUs */
+    kvm_disable_icps();
+
+    return rc;
+}
+
 static void xics_kvm_register_types(void)
 {
     type_register_static(&ics_kvm_info);
-- 
2.20.1