spapr: fix the value of SDR1 in kvmppc_put_books_sregs()

When running with KVM PR, if a new HPT is allocated we need to inform
KVM about the HPT address and size. This is currently done by hacking
the value of SDR1 and pushing it to KVM in several places.

Also, migration breaks the guest since it is very unlikely the HPT has
the same address in source and destination, but we push the incoming
value of SDR1 to KVM anyway.

This patch introduces a new virtual hypervisor hook so that the spapr
code can provide the correct value of SDR1 to be pushed to KVM each
time kvmppc_put_books_sregs() is called.

It allows to get rid of all the hacking in the spapr/kvmppc code and
it fixes migration of nested KVM PR.

Suggested-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 33 insertions, 12 deletions

diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index 57bb411394..8d72bb7c1c 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -686,6 +686,37 @@ static int rehash_hpt(PowerPCCPU *cpu,
     return H_SUCCESS;
 }
 
+static void do_push_sregs_to_kvm_pr(CPUState *cs, run_on_cpu_data data)
+{
+    int ret;
+
+    cpu_synchronize_state(cs);
+
+    ret = kvmppc_put_books_sregs(POWERPC_CPU(cs));
+    if (ret < 0) {
+        error_report("failed to push sregs to KVM: %s", strerror(-ret));
+        exit(1);
+    }
+}
+
+static void push_sregs_to_kvm_pr(sPAPRMachineState *spapr)
+{
+    CPUState *cs;
+
+    /*
+     * This is a hack for the benefit of KVM PR - it abuses the SDR1
+     * slot in kvm_sregs to communicate the userspace address of the
+     * HPT
+     */
+    if (!kvm_enabled() || !spapr->htab) {
+        return;
+    }
+
+    CPU_FOREACH(cs) {
+        run_on_cpu(cs, do_push_sregs_to_kvm_pr, RUN_ON_CPU_NULL);
+    }
+}
+
 static target_ulong h_resize_hpt_commit(PowerPCCPU *cpu,
                                         sPAPRMachineState *spapr,
                                         target_ulong opcode,
@@ -733,12 +764,7 @@ static target_ulong h_resize_hpt_commit(PowerPCCPU *cpu,
         spapr->htab = pending->hpt;
         spapr->htab_shift = pending->shift;
 
-        if (kvm_enabled()) {
-            /* For KVM PR, update the HPT pointer */
-            target_ulong sdr1 = (target_ulong)(uintptr_t)spapr->htab
-                | (spapr->htab_shift - 18);
-            kvmppc_update_sdr1(sdr1);
-        }
+        push_sregs_to_kvm_pr(spapr);
 
         pending->hpt = NULL; /* so it's not free()d */
     }
@@ -1564,12 +1590,7 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu,
              * the point this is called, nothing should have been
              * entered into the existing HPT */
             spapr_reallocate_hpt(spapr, maxshift, &error_fatal);
-            if (kvm_enabled()) {
-                /* For KVM PR, update the HPT pointer */
-                target_ulong sdr1 = (target_ulong)(uintptr_t)spapr->htab
-                    | (spapr->htab_shift - 18);
-                kvmppc_update_sdr1(sdr1);
-            }
+            push_sregs_to_kvm_pr(spapr);
         }
     }