diff mbox series

[PULL,41/88] spapr/xics: Configure number of servers in KVM

Message ID 20191217044322.351838-42-david@gibson.dropbear.id.au
State New
Headers show
Series [PULL,01/88] ppc/pnv: Add a PNOR model | expand

Commit Message

David Gibson Dec. 17, 2019, 4:42 a.m. UTC
From: Greg Kurz <groug@kaod.org>

The XICS-on-XIVE KVM devices now has an attribute to configure the number
of interrupt servers. This allows to greatly optimize the usage of the VP
space in the XIVE HW, and thus to start a lot more VMs.

Only set this attribute if available in order to support older POWER9 KVM
and pre-POWER9 XICS KVM devices.

The XICS-on-XIVE KVM device now reports the exhaustion of VPs upon the
connection of the first VCPU. Check that in order to have a chance to
provide a hint to the user.
`
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <157478678846.67101.9660531022460517710.stgit@bahia.tlslab.ibm.com>
Reviewed-by: C├ędric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/intc/xics_kvm.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
index a1f1b7b0d3..8d6156578f 100644
--- a/hw/intc/xics_kvm.c
+++ b/hw/intc/xics_kvm.c
@@ -165,8 +165,15 @@  void icp_kvm_realize(DeviceState *dev, Error **errp)
 
     ret = kvm_vcpu_enable_cap(cs, KVM_CAP_IRQ_XICS, 0, kernel_xics_fd, vcpu_id);
     if (ret < 0) {
-        error_setg(errp, "Unable to connect CPU%ld to kernel XICS: %s", vcpu_id,
-                   strerror(errno));
+        Error *local_err = NULL;
+
+        error_setg(&local_err, "Unable to connect CPU%ld to kernel XICS: %s",
+                   vcpu_id, strerror(errno));
+        if (errno == ENOSPC) {
+            error_append_hint(&local_err, "Try -smp maxcpus=N with N < %u\n",
+                              MACHINE(qdev_get_machine())->smp.max_cpus);
+        }
+        error_propagate(errp, local_err);
         return;
     }
     enabled_icp = g_malloc(sizeof(*enabled_icp));
@@ -399,6 +406,16 @@  int xics_kvm_connect(SpaprInterruptController *intc, uint32_t nr_servers,
         goto fail;
     }
 
+    /* Tell KVM about the # of VCPUs we may have (POWER9 and newer only) */
+    if (kvm_device_check_attr(rc, KVM_DEV_XICS_GRP_CTRL,
+                              KVM_DEV_XICS_NR_SERVERS)) {
+        if (kvm_device_access(rc, KVM_DEV_XICS_GRP_CTRL,
+                              KVM_DEV_XICS_NR_SERVERS, &nr_servers, true,
+                              &local_err)) {
+            goto fail;
+        }
+    }
+
     kernel_xics_fd = rc;
     kvm_kernel_irqchip = true;
     kvm_msi_via_irqfd_allowed = true;