[Qemu-devel] [PATCH v2 6/7] target-arm: Reinitialize all KVM VCPU registers on reset

[Peter Maydell <peter.maydell@linaro.org>]

Since the ARM KVM API doesn't include a "reset this VCPU"
ioctl, we have to capture the initial values of every
register it knows about so that we can reset the VCPU
by feeding those values back again.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target-arm/cpu-qom.h |    6 +++++-
 target-arm/kvm.c     |   16 ++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/target-arm/cpu-qom.h b/target-arm/cpu-qom.h
index 2242eee..25239b8 100644
--- a/target-arm/cpu-qom.h
+++ b/target-arm/cpu-qom.h
@@ -72,7 +72,11 @@ typedef struct ARMCPU {
     uint64_t *cpreg_indexes;
     /* Values of the registers (cpreg_indexes[i]'s value is cpreg_values[i]) */
     uint64_t *cpreg_values;
-    /* Length of the indexes, values arrays */
+    /* When using KVM, keeps a copy of the initial state of the VCPU,
+     * so that on reset we can feed the reset values back into the kernel.
+     */
+    uint64_t *cpreg_reset_values;
+    /* Length of the indexes, values, reset_values arrays */
     int32_t cpreg_array_len;
     /* These are used only for migration: incoming data arrives in
      * these fields and is sanity checked in post_load before copying
diff --git a/target-arm/kvm.c b/target-arm/kvm.c
index 746ae02..f4a835d 100644
--- a/target-arm/kvm.c
+++ b/target-arm/kvm.c
@@ -162,6 +162,13 @@ int kvm_arch_init_vcpu(CPUState *cs)
         goto out;
     }
 
+    /* Save a copy of the initial register values so that we can
+     * feed it back to the kernel on VCPU reset.
+     */
+    cpu->cpreg_reset_values = g_memdup(cpu->cpreg_values,
+                                       cpu->cpreg_array_len *
+                                       sizeof(cpu->cpreg_values[0]));
+
 out:
     g_free(rlp);
     return ret;
@@ -603,6 +610,15 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
 
 void kvm_arch_reset_vcpu(CPUState *cs)
 {
+    /* Feed the kernel back its initial register state */
+    ARMCPU *cpu = ARM_CPU(cs);
+
+    memmove(cpu->cpreg_values, cpu->cpreg_reset_values,
+            cpu->cpreg_array_len * sizeof(cpu->cpreg_values[0]));
+
+    if (!write_list_to_kvmstate(cpu)) {
+        abort();
+    }
 }
 
 bool kvm_arch_stop_on_emulation_error(CPUState *cs)
-- 
1.7.9.5