Re: [PATCH 5/5] plugins/core: allow reading of registers during discon events

[Julian Ganz]

Hi Alex,

November 28, 2025 at 7:21 PM, "Alex Bennée" wrote:
> We have protections that prevent callbacks that didn't declare
> themselves as wanting to access registers. However for discontinuities
> the system state is fully rectified so they should always be able to
> read the register values.
> 
> a1688bc86ce (plugins: add hooks for new discontinuity related callbacks)
> Signed-off-by: Alex Bennée 
> Cc: Julian Ganz 
> ---
>  plugins/core.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/plugins/core.c b/plugins/core.c
> index 8f8bc7219c2..b4b783008f7 100644
> --- a/plugins/core.c
> +++ b/plugins/core.c
> @@ -119,6 +119,7 @@ static void plugin_vcpu_cb__discon(CPUState *cpu,
>  struct qemu_plugin_cb *cb, *next;
>  uint64_t to = cpu->cc->get_pc(cpu);
>  
> + qemu_plugin_set_cb_flags(cpu, QEMU_PLUGIN_CB_RW_REGS);
>  if (cpu->cpu_index < plugin.num_vcpus) {
>  /* iterate safely; plugins might uninstall themselves at any time */
>  QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
> @@ -127,6 +128,7 @@ static void plugin_vcpu_cb__discon(CPUState *cpu,
>  func(cb->ctx->id, cpu->cpu_index, type, from, to);
>  }
>  }
> + qemu_plugin_set_cb_flags(cpu, QEMU_PLUGIN_CB_NO_REGS);
>  }

Yes, we definitely want this.

Reviewed-by: Julian Ganz 

Regards,
Julian

[PATCH 5/5] plugins/core: allow reading of registers during discon events

[Alex Bennée]

We have protections that prevent callbacks that didn't declare
themselves as wanting to access registers. However for discontinuities
the system state is fully rectified so they should always be able to
read the register values.

a1688bc86ce (plugins: add hooks for new discontinuity related callbacks)
Signed-off-by: Alex Bennée 
Cc: Julian Ganz 
---
 plugins/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/plugins/core.c b/plugins/core.c
index 8f8bc7219c2..b4b783008f7 100644
--- a/plugins/core.c
+++ b/plugins/core.c
@@ -119,6 +119,7 @@ static void plugin_vcpu_cb__discon(CPUState *cpu,
 struct qemu_plugin_cb *cb, *next;
 uint64_t to = cpu->cc->get_pc(cpu);
 
+qemu_plugin_set_cb_flags(cpu, QEMU_PLUGIN_CB_RW_REGS);
 if (cpu->cpu_index < plugin.num_vcpus) {
 /* iterate safely; plugins might uninstall themselves at any time */
 QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
@@ -127,6 +128,7 @@ static void plugin_vcpu_cb__discon(CPUState *cpu,
 func(cb->ctx->id, cpu->cpu_index, type, from, to);
 }
 }
+qemu_plugin_set_cb_flags(cpu, QEMU_PLUGIN_CB_NO_REGS);
 }
 
 /*
-- 
2.47.3