* [PATCH] TCG plugin API extension to read guest memory content by an address
@ 2023-02-16 16:18 Mikhail Tyutin
2023-02-16 16:30 ` Alex Bennée
2023-02-16 16:42 ` Peter Maydell
0 siblings, 2 replies; 3+ messages in thread
From: Mikhail Tyutin @ 2023-02-16 16:18 UTC (permalink / raw)
To: qemu-devel@nongnu.org
Cc: alex.bennee@linaro.org, erdnaxe@crans.org, ma.mandourr@gmail.com
TCG plugin API extension to read guest memory content. qemu_plugin_vcpu_read_phys_mem()
function can be used by TCG plugin inside of qemu_plugin_vcpu_mem_cb_t callback to adjust
received address according to internal memory mappings and read content of guest memory.
Works for both user-level and system-level emulation modes.
Signed-off-by: Mikhail Tyutin <m.tyutin@yadro.com>
Signed-off-by: Aleksey Titov <a.titov@yadro.com>
---
QEMU_PLUGIN_READ_PHYS_MEM_ENABLED define below is to let plugins to check if this API
is available in Qemu build.
include/qemu/qemu-plugin.h | 18 ++++++++++++++++++
plugins/api.c | 20 ++++++++++++++++++++
plugins/qemu-plugins.symbols | 1 +
3 files changed, 39 insertions(+)
diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
index d0e9d03adf..576597f601 100644
--- a/include/qemu/qemu-plugin.h
+++ b/include/qemu/qemu-plugin.h
@@ -625,4 +625,22 @@ uint64_t qemu_plugin_end_code(void);
*/
uint64_t qemu_plugin_entry_code(void);
+
+#define QEMU_PLUGIN_READ_PHYS_MEM_ENABLED
+/**
+ * qemu_plugin_vcpu_read_phys_mem() - reads guest's memory content
+ *
+ * @vcpu_index: vcpu index
+ * @addr: guest's virtual address
+ * @buf: destination buffer to read data to
+ * @len: number of bytes to read
+ *
+ * Adjusts address according to internal memory mapping and reads
+ * content of guest memory.
+ */
+void qemu_plugin_vcpu_read_phys_mem(unsigned int vcpu_index,
+ uint64_t addr,
+ void *buf,
+ uint64_t len);
+
#endif /* QEMU_QEMU_PLUGIN_H */
diff --git a/plugins/api.c b/plugins/api.c
index 2078b16edb..95753bce95 100644
--- a/plugins/api.c
+++ b/plugins/api.c
@@ -442,3 +442,23 @@ uint64_t qemu_plugin_entry_code(void)
#endif
return entry;
}
+
+void qemu_plugin_vcpu_read_phys_mem(unsigned int vcpu_index,
+ uint64_t addr,
+ void *buf,
+ uint64_t len) {
+#ifndef CONFIG_USER_ONLY
+ cpu_physical_memory_rw(addr, buf, len, false);
+#else
+ CPUClass *cc;
+ CPUState *cpu;
+
+ cpu = qemu_get_cpu(vcpu_index);
+ cc = CPU_GET_CLASS(cpu);
+ if (cc->memory_rw_debug) {
+ cc->memory_rw_debug(cpu, addr, buf, len, false);
+ } else {
+ cpu_memory_rw_debug(cpu, addr, buf, len, false);
+ }
+#endif
+}
\ No newline at end of file
diff --git a/plugins/qemu-plugins.symbols b/plugins/qemu-plugins.symbols
index 71f6c90549..f0ce8c730f 100644
--- a/plugins/qemu-plugins.symbols
+++ b/plugins/qemu-plugins.symbols
@@ -42,4 +42,5 @@
qemu_plugin_tb_vaddr;
qemu_plugin_uninstall;
qemu_plugin_vcpu_for_each;
+ qemu_plugin_vcpu_read_phys_mem;
};
--
2.34.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] TCG plugin API extension to read guest memory content by an address
2023-02-16 16:18 [PATCH] TCG plugin API extension to read guest memory content by an address Mikhail Tyutin
@ 2023-02-16 16:30 ` Alex Bennée
2023-02-16 16:42 ` Peter Maydell
1 sibling, 0 replies; 3+ messages in thread
From: Alex Bennée @ 2023-02-16 16:30 UTC (permalink / raw)
To: Mikhail Tyutin
Cc: qemu-devel@nongnu.org, erdnaxe@crans.org, ma.mandourr@gmail.com
Mikhail Tyutin <m.tyutin@yadro.com> writes:
> TCG plugin API extension to read guest memory content. qemu_plugin_vcpu_read_phys_mem()
> function can be used by TCG plugin inside of qemu_plugin_vcpu_mem_cb_t callback to adjust
> received address according to internal memory mappings and read content of guest memory.
> Works for both user-level and system-level emulation modes.
>
> Signed-off-by: Mikhail Tyutin <m.tyutin@yadro.com>
> Signed-off-by: Aleksey Titov <a.titov@yadro.com>
> ---
> QEMU_PLUGIN_READ_PHYS_MEM_ENABLED define below is to let plugins to check if this API
> is available in Qemu build.
>
> include/qemu/qemu-plugin.h | 18 ++++++++++++++++++
> plugins/api.c | 20 ++++++++++++++++++++
> plugins/qemu-plugins.symbols | 1 +
> 3 files changed, 39 insertions(+)
>
> diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
> index d0e9d03adf..576597f601 100644
> --- a/include/qemu/qemu-plugin.h
> +++ b/include/qemu/qemu-plugin.h
> @@ -625,4 +625,22 @@ uint64_t qemu_plugin_end_code(void);
> */
> uint64_t qemu_plugin_entry_code(void);
>
> +
> +#define QEMU_PLUGIN_READ_PHYS_MEM_ENABLED
We don't need this - we should update the plugin API version instead.
> +/**
> + * qemu_plugin_vcpu_read_phys_mem() - reads guest's memory content
> + *
> + * @vcpu_index: vcpu index
> + * @addr: guest's virtual address
> + * @buf: destination buffer to read data to
> + * @len: number of bytes to read
> + *
> + * Adjusts address according to internal memory mapping and reads
> + * content of guest memory.
> + */
> +void qemu_plugin_vcpu_read_phys_mem(unsigned int vcpu_index,
> + uint64_t addr,
> + void *buf,
> + uint64_t len);
> +
> #endif /* QEMU_QEMU_PLUGIN_H */
> diff --git a/plugins/api.c b/plugins/api.c
> index 2078b16edb..95753bce95 100644
> --- a/plugins/api.c
> +++ b/plugins/api.c
> @@ -442,3 +442,23 @@ uint64_t qemu_plugin_entry_code(void)
> #endif
> return entry;
> }
> +
> +void qemu_plugin_vcpu_read_phys_mem(unsigned int vcpu_index,
> + uint64_t addr,
> + void *buf,
> + uint64_t len) {
> +#ifndef CONFIG_USER_ONLY
> + cpu_physical_memory_rw(addr, buf, len, false);
> +#else
> + CPUClass *cc;
> + CPUState *cpu;
> +
> + cpu = qemu_get_cpu(vcpu_index);
> + cc = CPU_GET_CLASS(cpu);
> + if (cc->memory_rw_debug) {
> + cc->memory_rw_debug(cpu, addr, buf, len, false);
> + } else {
> + cpu_memory_rw_debug(cpu, addr, buf, len, false);
> + }
> +#endif
> +}
I'm wary about this because what memory is the plugin going to be
looking at? There are certainly no guarantees the memory contain the
value that has just been loaded or stored by the instrumented
instruction.
I certainly prefer to see example plugins that use new APIs in the same
patch series to help in assessing if the API is useful or flawed for the
purpose its being suggested for.
> \ No newline at end of file
> diff --git a/plugins/qemu-plugins.symbols b/plugins/qemu-plugins.symbols
> index 71f6c90549..f0ce8c730f 100644
> --- a/plugins/qemu-plugins.symbols
> +++ b/plugins/qemu-plugins.symbols
> @@ -42,4 +42,5 @@
> qemu_plugin_tb_vaddr;
> qemu_plugin_uninstall;
> qemu_plugin_vcpu_for_each;
> + qemu_plugin_vcpu_read_phys_mem;
> };
--
Alex Bennée
Virtualisation Tech Lead @ Linaro
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] TCG plugin API extension to read guest memory content by an address
2023-02-16 16:18 [PATCH] TCG plugin API extension to read guest memory content by an address Mikhail Tyutin
2023-02-16 16:30 ` Alex Bennée
@ 2023-02-16 16:42 ` Peter Maydell
1 sibling, 0 replies; 3+ messages in thread
From: Peter Maydell @ 2023-02-16 16:42 UTC (permalink / raw)
To: Mikhail Tyutin
Cc: qemu-devel@nongnu.org, alex.bennee@linaro.org, erdnaxe@crans.org,
ma.mandourr@gmail.com
On Thu, 16 Feb 2023 at 16:18, Mikhail Tyutin <m.tyutin@yadro.com> wrote:
>
> TCG plugin API extension to read guest memory content. qemu_plugin_vcpu_read_phys_mem()
> function can be used by TCG plugin inside of qemu_plugin_vcpu_mem_cb_t callback to adjust
> received address according to internal memory mappings and read content of guest memory.
> Works for both user-level and system-level emulation modes.
>
> Signed-off-by: Mikhail Tyutin <m.tyutin@yadro.com>
> Signed-off-by: Aleksey Titov <a.titov@yadro.com>
> +/**
> + * qemu_plugin_vcpu_read_phys_mem() - reads guest's memory content
> + *
> + * @vcpu_index: vcpu index
> + * @addr: guest's virtual address
> + * @buf: destination buffer to read data to
> + * @len: number of bytes to read
> + *
> + * Adjusts address according to internal memory mapping and reads
> + * content of guest memory.
> + */
> +void qemu_plugin_vcpu_read_phys_mem(unsigned int vcpu_index,
> + uint64_t addr,
> + void *buf,
> + uint64_t len);
> +
> #endif /* QEMU_QEMU_PLUGIN_H */
> diff --git a/plugins/api.c b/plugins/api.c
> index 2078b16edb..95753bce95 100644
> --- a/plugins/api.c
> +++ b/plugins/api.c
> @@ -442,3 +442,23 @@ uint64_t qemu_plugin_entry_code(void)
> #endif
> return entry;
> }
> +
> +void qemu_plugin_vcpu_read_phys_mem(unsigned int vcpu_index,
> + uint64_t addr,
> + void *buf,
> + uint64_t len) {
> +#ifndef CONFIG_USER_ONLY
> + cpu_physical_memory_rw(addr, buf, len, false);
This is the wrong API to use, because "physical memory at
address X" can differ depending on what CPU you are and
what state that CPU is in.
> +#else
> + CPUClass *cc;
> + CPUState *cpu;
> +
> + cpu = qemu_get_cpu(vcpu_index);
> + cc = CPU_GET_CLASS(cpu);
> + if (cc->memory_rw_debug) {
> + cc->memory_rw_debug(cpu, addr, buf, len, false);
> + } else {
> + cpu_memory_rw_debug(cpu, addr, buf, len, false);
> + }
These ones are a bit better.
> +#endif
> +}
> \ No newline at end of file
-- PMM
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2023-02-16 16:42 UTC | newest]
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2023-02-16 16:18 [PATCH] TCG plugin API extension to read guest memory content by an address Mikhail Tyutin
2023-02-16 16:30 ` Alex Bennée
2023-02-16 16:42 ` Peter Maydell
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