On Wed, 22 Nov 2023 at 12:17, Mikhail Tyutin <m.tyu...@yadro.com> wrote:
>
> In system mode emulation, some of translation blocks could be
> interrupted on memory I/O operation. That leads to artificial
> construction of another translation block that contains memory
> operation only. If TCG plugin is not aware of that TB kind, it
> attempts to insert execution callbacks either on translation
> block or instruction, which is silently ignored. As the result
> it leads to potentially inconsistent processing of execution and
> memory callbacks by the plugin.
> Exposing appropriate translation block flag allows plugins to
> handle "memory only" blocks in appropriate way.
>
> Signed-off-by: Mikhail Tyutin <m.tyu...@yadro.com>
> ---
> include/qemu/qemu-plugin.h | 29 ++++++++++++++++++++++++++++-
> plugins/api.c | 14 ++++++++++++++
> plugins/qemu-plugins.symbols | 1 +
> 3 files changed, 43 insertions(+), 1 deletion(-)
>
> diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
> index 4daab6efd2..5f07fa497c 100644
> --- a/include/qemu/qemu-plugin.h
> +++ b/include/qemu/qemu-plugin.h
> @@ -54,7 +54,7 @@ typedef uint64_t qemu_plugin_id_t;
>
> extern QEMU_PLUGIN_EXPORT int qemu_plugin_version;
>
> -#define QEMU_PLUGIN_VERSION 1
> +#define QEMU_PLUGIN_VERSION 2
>
> /**
> * struct qemu_info_t - system information for plugins
> @@ -236,6 +236,21 @@ enum qemu_plugin_cb_flags {
> QEMU_PLUGIN_CB_RW_REGS,
> };
>
> +/**
> + * enum qemu_plugin_tb_flags - type of translation block
> + *
> + * @QEMU_PLUGIN_TB_MEM_ONLY:
> + * TB is special block to perform memory I/O operation only.
> + * Block- and instruction- level callbacks have no effect.
> + * @QEMU_PLUGIN_TB_MEM_OPS:
> + * TB has at least one instruction that access memory.
> + * Memory callbacks are applicable to this TB.
> + */
> +enum qemu_plugin_tb_flags {
> + QEMU_PLUGIN_TB_MEM_ONLY = 0x01,
> + QEMU_PLUGIN_TB_MEM_OPS = 0x02
> +};
>
If we do go for this, can we pick a different naming
than "TB flags", please? QEMU already has a "TB flags"
concept for TCG -- it's the target-specific flags that
encode bits of the CPU state that we baked into the
generated code. Those flags are strictly TCG internal
and we definitely don't want to expose them to a plugin
because they're not a stable interface. So we should
call these flags something else so we don't get confused.
thanks
-- PMM
