plugins/core: allow reading of registers during discon events

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

Alex Bennée posted 1 patch 2 months, 1 week ago

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git fetch https://github.com/patchew-project/qemu tags/patchew/20251128164220.3985408-1-alex.bennee@linaro.org

Maintainers: "Alex Bennée" <alex.bennee@linaro.org>, Alexandre Iooss <erdnaxe@crans.org>, Mahmoud Mandour <ma.mandourr@gmail.com>, Pierrick Bouvier <pierrick.bouvier@linaro.org>

plugins/core.c | 2 ++
1 file changed, 2 insertions(+)

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

Posted by Alex Bennée 2 months, 1 week ago

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 <alex.bennee@linaro.org>
Cc: Julian Ganz <neither@nut.email>
---
 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

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

Posted by Pierrick Bouvier 2 months, 1 week ago

On 11/28/25 8:42 AM, 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 <alex.bennee@linaro.org>
> Cc: Julian Ganz <neither@nut.email>
> ---
>   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);
>   }
>   
>   /*

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>