* [PATCH v6 0/9] Add additional plugin API functions to read and write memory and registers
@ 2025-06-02 6:08 Rowan Hart
2025-06-02 6:08 ` [PATCH v6 1/9] gdbstub: Expose gdb_write_register function to consumers of gdbstub Rowan Hart
` (8 more replies)
0 siblings, 9 replies; 10+ messages in thread
From: Rowan Hart @ 2025-06-02 6:08 UTC (permalink / raw)
To: qemu-devel
Cc: Yanan Wang, Richard Henderson, Alexandre Iooss, Zhao Liu,
Eduardo Habkost, Mahmoud Mandour, Alex Bennée,
Pierrick Bouvier, Philippe Mathieu-Daudé, Paolo Bonzini,
Marcel Apfelbaum, Rowan Hart
This patch series adds several new API functions focused on enabling use
cases around reading and writing guest memory from QEMU plugins. To support
these new APIs, some utility functionality around retrieving information about
address spaces is added as well.
The new qemu_plugin_write_register utilizes gdb_write_register, which is now
declared in gdbstub.h for this purpose instead of being static.
qemu_plugin_write_memory_vaddr utilizes cpu_memory_rw_debug much the same as
the existing read_memory_vaddr function does.
The read and write_hwaddr functions are the most different. These functions
use address_space_rw, which works well in most cases. There is an important
caveat that for writes, the page being written will be set dirty by the
write operation. This dirty setting requires locking the page range,
which can contend with an already held lock in page_collection_lock
when called in a tb translate callback with a write to the instruction
memory in the tb. The doc comments warn against doing this, and it's unlikely
anyone would want to do this.
I've also added two test plugins: one that implements a simple hypercall
interface that guest code can use to communicate with the plugin in a
structured way with a test to ensure that this hypercall works and writing
virtual memory works. And one that implements a simple patch utility to patch
memory at runtime. The test for the second plugin ensures the patch applies
successfully to instruction memory, and can use both hw and vaddr methods.
For v3, I've had a few comments from the last submission that I've addressed,
and some that I haven't for one reason or another:
- Enforce QEMU_PLUGIN_CB_ flags in register read/write operations: done!
- Fix my commit messages and add long messages describing commits: done!
- Un-expose AS internals: done! Functions operate on current vCPU, current AS.
- Clean up use of current_cpu: done!
- Make functions take a vcpu_idx: not done. May revisit but it allows footguns.
Even for translation, seems best to not do this now. We can easily add _vcpu
versions of these functions in the future if we change our minds!
For v5, I've just updated the enforcement of the QEMU_PLUGIN_CB_ flags to just
use immediate stores, which simplifies the implementation quite a lot and
should be more efficient too. Thanks Pierrick for the suggestion!
v6 is a formatting pass, I left some whitespace that needed removal, some
license text was wrong, and so forth.
Rowan Hart (2):
plugins: Add enforcement of QEMU_PLUGIN_CB flags in register R/W
callbacks
plugins: Remove use of qemu_plugin_read_register where it is not
permitted
novafacing (7):
gdbstub: Expose gdb_write_register function to consumers of gdbstub
plugins: Add register write API
plugins: Add memory virtual address write API
plugins: Add memory hardware address read/write API
plugins: Add patcher plugin and test
plugins: Add hypercalls plugin and test
plugins: Update plugin version and add notes
accel/tcg/plugin-gen.c | 30 +
gdbstub/gdbstub.c | 2 +-
include/exec/gdbstub.h | 14 +
include/hw/core/cpu.h | 1 +
include/qemu/plugin.h | 4 +
include/qemu/qemu-plugin.h | 166 +++++-
plugins/api.c | 135 ++++-
plugins/core.c | 32 +-
tests/tcg/Makefile.target | 2 +
tests/tcg/plugins/hypercalls.c | 547 ++++++++++++++++++
tests/tcg/plugins/insn.c | 22 +-
tests/tcg/plugins/meson.build | 2 +-
tests/tcg/plugins/patch.c | 297 ++++++++++
tests/tcg/x86_64/Makefile.softmmu-target | 36 +-
tests/tcg/x86_64/system/hypercalls-target.c | 40 ++
tests/tcg/x86_64/system/patch-target.c | 27 +
.../tcg/x86_64/system/validate-hypercalls.py | 40 ++
tests/tcg/x86_64/system/validate-patch.py | 39 ++
18 files changed, 1386 insertions(+), 50 deletions(-)
create mode 100644 tests/tcg/plugins/hypercalls.c
create mode 100644 tests/tcg/plugins/patch.c
create mode 100644 tests/tcg/x86_64/system/hypercalls-target.c
create mode 100644 tests/tcg/x86_64/system/patch-target.c
create mode 100755 tests/tcg/x86_64/system/validate-hypercalls.py
create mode 100755 tests/tcg/x86_64/system/validate-patch.py
--
2.49.0
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v6 1/9] gdbstub: Expose gdb_write_register function to consumers of gdbstub
2025-06-02 6:08 [PATCH v6 0/9] Add additional plugin API functions to read and write memory and registers Rowan Hart
@ 2025-06-02 6:08 ` Rowan Hart
2025-06-02 6:08 ` [PATCH v6 2/9] plugins: Add register write API Rowan Hart
` (7 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: Rowan Hart @ 2025-06-02 6:08 UTC (permalink / raw)
To: qemu-devel
Cc: Yanan Wang, Richard Henderson, Alexandre Iooss, Zhao Liu,
Eduardo Habkost, Mahmoud Mandour, Alex Bennée,
Pierrick Bouvier, Philippe Mathieu-Daudé, Paolo Bonzini,
Marcel Apfelbaum, novafacing
From: novafacing <rowanbhart@gmail.com>
This patch exposes the gdb_write_register function from
gdbstub/gdbstub.c via the exec/gdbstub.h header file to support use in
plugins to write register contents.
Signed-off-by: novafacing <rowanbhart@gmail.com>
Signed-off-by: Rowan Hart <rowanbhart@gmail.com>
---
gdbstub/gdbstub.c | 2 +-
include/exec/gdbstub.h | 14 ++++++++++++++
2 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
index 565f6b33a9..5846e481be 100644
--- a/gdbstub/gdbstub.c
+++ b/gdbstub/gdbstub.c
@@ -534,7 +534,7 @@ int gdb_read_register(CPUState *cpu, GByteArray *buf, int reg)
return 0;
}
-static int gdb_write_register(CPUState *cpu, uint8_t *mem_buf, int reg)
+int gdb_write_register(CPUState *cpu, uint8_t *mem_buf, int reg)
{
GDBRegisterState *r;
diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
index 0675b0b646..a16c0051ce 100644
--- a/include/exec/gdbstub.h
+++ b/include/exec/gdbstub.h
@@ -124,6 +124,20 @@ const GDBFeature *gdb_find_static_feature(const char *xmlname);
*/
int gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
+/**
+ * gdb_write_register() - Write a register associated with a CPU.
+ * @cpu: The CPU associated with the register.
+ * @buf: The buffer that the register contents will be set to.
+ * @reg: The register's number returned by gdb_find_feature_register().
+ *
+ * The size of @buf must be at least the size of the register being
+ * written.
+ *
+ * Return: The number of written bytes, or 0 if an error occurred (for
+ * example, an unknown register was provided).
+ */
+int gdb_write_register(CPUState *cpu, uint8_t *mem_buf, int reg);
+
/**
* typedef GDBRegDesc - a register description from gdbstub
*/
--
2.49.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH v6 2/9] plugins: Add register write API
2025-06-02 6:08 [PATCH v6 0/9] Add additional plugin API functions to read and write memory and registers Rowan Hart
2025-06-02 6:08 ` [PATCH v6 1/9] gdbstub: Expose gdb_write_register function to consumers of gdbstub Rowan Hart
@ 2025-06-02 6:08 ` Rowan Hart
2025-06-02 6:08 ` [PATCH v6 3/9] plugins: Add enforcement of QEMU_PLUGIN_CB flags in register R/W callbacks Rowan Hart
` (6 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: Rowan Hart @ 2025-06-02 6:08 UTC (permalink / raw)
To: qemu-devel
Cc: Yanan Wang, Richard Henderson, Alexandre Iooss, Zhao Liu,
Eduardo Habkost, Mahmoud Mandour, Alex Bennée,
Pierrick Bouvier, Philippe Mathieu-Daudé, Paolo Bonzini,
Marcel Apfelbaum, novafacing
From: novafacing <rowanbhart@gmail.com>
This patch adds a function to the plugins API to allow plugins to write
register contents. It also moves the qemu_plugin_read_register function
so all the register-related functions are grouped together in the file.
Signed-off-by: novafacing <rowanbhart@gmail.com>
Signed-off-by: Rowan Hart <rowanbhart@gmail.com>
---
include/qemu/qemu-plugin.h | 54 ++++++++++++++++++++++++++------------
plugins/api.c | 22 +++++++++++-----
2 files changed, 52 insertions(+), 24 deletions(-)
diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
index 3a850aa216..cfe1692ecb 100644
--- a/include/qemu/qemu-plugin.h
+++ b/include/qemu/qemu-plugin.h
@@ -871,7 +871,8 @@ struct qemu_plugin_register;
/**
* typedef qemu_plugin_reg_descriptor - register descriptions
*
- * @handle: opaque handle for retrieving value with qemu_plugin_read_register
+ * @handle: opaque handle for retrieving value with qemu_plugin_read_register or
+ * writing value with qemu_plugin_write_register
* @name: register name
* @feature: optional feature descriptor, can be NULL
*/
@@ -893,6 +894,41 @@ typedef struct {
QEMU_PLUGIN_API
GArray *qemu_plugin_get_registers(void);
+/**
+ * qemu_plugin_read_register() - read register for current vCPU
+ *
+ * @handle: a @qemu_plugin_reg_handle handle
+ * @buf: A GByteArray for the data owned by the plugin
+ *
+ * This function is only available in a context that register read access is
+ * explicitly requested via the QEMU_PLUGIN_CB_R_REGS flag.
+ *
+ * Returns the size of the read register. The content of @buf is in target byte
+ * order. On failure returns -1.
+ */
+QEMU_PLUGIN_API
+int qemu_plugin_read_register(struct qemu_plugin_register *handle,
+ GByteArray *buf);
+
+/**
+ * qemu_plugin_write_register() - write register for current vCPU
+ *
+ * @handle: a @qemu_plugin_reg_handle handle
+ * @buf: A GByteArray for the data owned by the plugin
+ *
+ * This function is only available in a context that register write access is
+ * explicitly requested via the QEMU_PLUGIN_CB_RW_REGS flag.
+ *
+ * The size of @buf must be at least the size of the requested register.
+ * Attempting to write a register with @buf smaller than the register size
+ * will result in a crash or other undesired behavior.
+ *
+ * Returns the number of bytes written. On failure returns 0.
+ */
+QEMU_PLUGIN_API
+int qemu_plugin_write_register(struct qemu_plugin_register *handle,
+ GByteArray *buf);
+
/**
* qemu_plugin_read_memory_vaddr() - read from memory using a virtual address
*
@@ -915,22 +951,6 @@ QEMU_PLUGIN_API
bool qemu_plugin_read_memory_vaddr(uint64_t addr,
GByteArray *data, size_t len);
-/**
- * qemu_plugin_read_register() - read register for current vCPU
- *
- * @handle: a @qemu_plugin_reg_handle handle
- * @buf: A GByteArray for the data owned by the plugin
- *
- * This function is only available in a context that register read access is
- * explicitly requested via the QEMU_PLUGIN_CB_R_REGS flag.
- *
- * Returns the size of the read register. The content of @buf is in target byte
- * order. On failure returns -1.
- */
-QEMU_PLUGIN_API
-int qemu_plugin_read_register(struct qemu_plugin_register *handle,
- GByteArray *buf);
-
/**
* qemu_plugin_scoreboard_new() - alloc a new scoreboard
*
diff --git a/plugins/api.c b/plugins/api.c
index 3c9d4832e9..3a7add50d2 100644
--- a/plugins/api.c
+++ b/plugins/api.c
@@ -433,6 +433,21 @@ GArray *qemu_plugin_get_registers(void)
return create_register_handles(regs);
}
+int qemu_plugin_read_register(struct qemu_plugin_register *reg, GByteArray *buf)
+{
+ g_assert(current_cpu);
+
+ return gdb_read_register(current_cpu, buf, GPOINTER_TO_INT(reg) - 1);
+}
+
+int qemu_plugin_write_register(struct qemu_plugin_register *reg,
+ GByteArray *buf)
+{
+ g_assert(current_cpu);
+
+ return gdb_write_register(current_cpu, buf->data, GPOINTER_TO_INT(reg) - 1);
+}
+
bool qemu_plugin_read_memory_vaddr(uint64_t addr, GByteArray *data, size_t len)
{
g_assert(current_cpu);
@@ -453,13 +468,6 @@ bool qemu_plugin_read_memory_vaddr(uint64_t addr, GByteArray *data, size_t len)
return true;
}
-int qemu_plugin_read_register(struct qemu_plugin_register *reg, GByteArray *buf)
-{
- g_assert(current_cpu);
-
- return gdb_read_register(current_cpu, buf, GPOINTER_TO_INT(reg) - 1);
-}
-
struct qemu_plugin_scoreboard *qemu_plugin_scoreboard_new(size_t element_size)
{
return plugin_scoreboard_new(element_size);
--
2.49.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH v6 3/9] plugins: Add enforcement of QEMU_PLUGIN_CB flags in register R/W callbacks
2025-06-02 6:08 [PATCH v6 0/9] Add additional plugin API functions to read and write memory and registers Rowan Hart
2025-06-02 6:08 ` [PATCH v6 1/9] gdbstub: Expose gdb_write_register function to consumers of gdbstub Rowan Hart
2025-06-02 6:08 ` [PATCH v6 2/9] plugins: Add register write API Rowan Hart
@ 2025-06-02 6:08 ` Rowan Hart
2025-06-02 6:08 ` [PATCH v6 4/9] plugins: Add memory virtual address write API Rowan Hart
` (5 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: Rowan Hart @ 2025-06-02 6:08 UTC (permalink / raw)
To: qemu-devel
Cc: Yanan Wang, Richard Henderson, Alexandre Iooss, Zhao Liu,
Eduardo Habkost, Mahmoud Mandour, Alex Bennée,
Pierrick Bouvier, Philippe Mathieu-Daudé, Paolo Bonzini,
Marcel Apfelbaum, Rowan Hart
This patch adds functionality to enforce the requested QEMU_PLUGIN_CB_
flags level passed when registering a callback function using the
plugins API. Each time a callback is about to be invoked, a thread-local
variable will be updated with the level that callback requested. Then,
called API functions (in particular, the register read and write API)
will call qemu_plugin_get_cb_flags() to check the level is at least the
level they require.
Signed-off-by: Rowan Hart <rowanbhart@gmail.com>
---
accel/tcg/plugin-gen.c | 30 ++++++++++++++++++++++++++++++
include/hw/core/cpu.h | 1 +
include/qemu/plugin.h | 4 ++++
include/qemu/qemu-plugin.h | 3 ---
plugins/api.c | 8 ++++++++
plugins/core.c | 32 ++++++++++++++++++++++++++------
6 files changed, 69 insertions(+), 9 deletions(-)
diff --git a/accel/tcg/plugin-gen.c b/accel/tcg/plugin-gen.c
index c1da753894..9920381a84 100644
--- a/accel/tcg/plugin-gen.c
+++ b/accel/tcg/plugin-gen.c
@@ -117,10 +117,20 @@ static TCGv_i32 gen_cpu_index(void)
static void gen_udata_cb(struct qemu_plugin_regular_cb *cb)
{
TCGv_i32 cpu_index = gen_cpu_index();
+ enum qemu_plugin_cb_flags cb_flags =
+ tcg_call_to_qemu_plugin_cb_flags(cb->info->flags);
+ TCGv_i32 flags = tcg_constant_i32(cb_flags);
+ TCGv_i32 clear_flags = tcg_constant_i32(QEMU_PLUGIN_CB_NO_REGS);
+ tcg_gen_st_i32(flags, tcg_env,
+ offsetof(CPUState, neg.plugin_cb_flags) - sizeof(CPUState));
tcg_gen_call2(cb->f.vcpu_udata, cb->info, NULL,
tcgv_i32_temp(cpu_index),
tcgv_ptr_temp(tcg_constant_ptr(cb->userp)));
+ tcg_gen_st_i32(clear_flags, tcg_env,
+ offsetof(CPUState, neg.plugin_cb_flags) - sizeof(CPUState));
tcg_temp_free_i32(cpu_index);
+ tcg_temp_free_i32(flags);
+ tcg_temp_free_i32(clear_flags);
}
static TCGv_ptr gen_plugin_u64_ptr(qemu_plugin_u64 entry)
@@ -173,10 +183,20 @@ static void gen_udata_cond_cb(struct qemu_plugin_conditional_cb *cb)
tcg_gen_ld_i64(val, ptr, 0);
tcg_gen_brcondi_i64(cond, val, cb->imm, after_cb);
TCGv_i32 cpu_index = gen_cpu_index();
+ enum qemu_plugin_cb_flags cb_flags =
+ tcg_call_to_qemu_plugin_cb_flags(cb->info->flags);
+ TCGv_i32 flags = tcg_constant_i32(cb_flags);
+ TCGv_i32 clear_flags = tcg_constant_i32(QEMU_PLUGIN_CB_NO_REGS);
+ tcg_gen_st_i32(flags, tcg_env,
+ offsetof(CPUState, neg.plugin_cb_flags) - sizeof(CPUState));
tcg_gen_call2(cb->f.vcpu_udata, cb->info, NULL,
tcgv_i32_temp(cpu_index),
tcgv_ptr_temp(tcg_constant_ptr(cb->userp)));
+ tcg_gen_st_i32(clear_flags, tcg_env,
+ offsetof(CPUState, neg.plugin_cb_flags) - sizeof(CPUState));
tcg_temp_free_i32(cpu_index);
+ tcg_temp_free_i32(flags);
+ tcg_temp_free_i32(clear_flags);
gen_set_label(after_cb);
tcg_temp_free_i64(val);
@@ -210,12 +230,22 @@ static void gen_mem_cb(struct qemu_plugin_regular_cb *cb,
qemu_plugin_meminfo_t meminfo, TCGv_i64 addr)
{
TCGv_i32 cpu_index = gen_cpu_index();
+ enum qemu_plugin_cb_flags cb_flags =
+ tcg_call_to_qemu_plugin_cb_flags(cb->info->flags);
+ TCGv_i32 flags = tcg_constant_i32(cb_flags);
+ TCGv_i32 clear_flags = tcg_constant_i32(QEMU_PLUGIN_CB_NO_REGS);
+ tcg_gen_st_i32(flags, tcg_env,
+ offsetof(CPUState, neg.plugin_cb_flags) - sizeof(CPUState));
tcg_gen_call4(cb->f.vcpu_mem, cb->info, NULL,
tcgv_i32_temp(cpu_index),
tcgv_i32_temp(tcg_constant_i32(meminfo)),
tcgv_i64_temp(addr),
tcgv_ptr_temp(tcg_constant_ptr(cb->userp)));
+ tcg_gen_st_i32(clear_flags, tcg_env,
+ offsetof(CPUState, neg.plugin_cb_flags) - sizeof(CPUState));
tcg_temp_free_i32(cpu_index);
+ tcg_temp_free_i32(flags);
+ tcg_temp_free_i32(clear_flags);
}
static void inject_cb(struct qemu_plugin_dyn_cb *cb)
diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index 1e87f7d393..d3cc9a5224 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -368,6 +368,7 @@ typedef struct CPUNegativeOffsetState {
GArray *plugin_mem_cbs;
uint64_t plugin_mem_value_low;
uint64_t plugin_mem_value_high;
+ int32_t plugin_cb_flags;
#endif
IcountDecr icount_decr;
bool can_do_io;
diff --git a/include/qemu/plugin.h b/include/qemu/plugin.h
index 9726a9ebf3..2fef2e7d71 100644
--- a/include/qemu/plugin.h
+++ b/include/qemu/plugin.h
@@ -209,6 +209,10 @@ void qemu_plugin_user_prefork_lock(void);
*/
void qemu_plugin_user_postfork(bool is_child);
+enum qemu_plugin_cb_flags tcg_call_to_qemu_plugin_cb_flags(int flags);
+
+enum qemu_plugin_cb_flags qemu_plugin_get_cb_flags(void);
+
#else /* !CONFIG_PLUGIN */
static inline void qemu_plugin_add_opts(void)
diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
index cfe1692ecb..120fb626a6 100644
--- a/include/qemu/qemu-plugin.h
+++ b/include/qemu/qemu-plugin.h
@@ -254,9 +254,6 @@ typedef struct {
* @QEMU_PLUGIN_CB_NO_REGS: callback does not access the CPU's regs
* @QEMU_PLUGIN_CB_R_REGS: callback reads the CPU's regs
* @QEMU_PLUGIN_CB_RW_REGS: callback reads and writes the CPU's regs
- *
- * Note: currently QEMU_PLUGIN_CB_RW_REGS is unused, plugins cannot change
- * system register state.
*/
enum qemu_plugin_cb_flags {
QEMU_PLUGIN_CB_NO_REGS,
diff --git a/plugins/api.c b/plugins/api.c
index 3a7add50d2..16141f5c25 100644
--- a/plugins/api.c
+++ b/plugins/api.c
@@ -437,6 +437,10 @@ int qemu_plugin_read_register(struct qemu_plugin_register *reg, GByteArray *buf)
{
g_assert(current_cpu);
+ if (qemu_plugin_get_cb_flags() == QEMU_PLUGIN_CB_NO_REGS) {
+ return -1;
+ }
+
return gdb_read_register(current_cpu, buf, GPOINTER_TO_INT(reg) - 1);
}
@@ -445,6 +449,10 @@ int qemu_plugin_write_register(struct qemu_plugin_register *reg,
{
g_assert(current_cpu);
+ if (buf->len == 0 || qemu_plugin_get_cb_flags() != QEMU_PLUGIN_CB_RW_REGS) {
+ return 0;
+ }
+
return gdb_write_register(current_cpu, buf->data, GPOINTER_TO_INT(reg) - 1);
}
diff --git a/plugins/core.c b/plugins/core.c
index eb9281fe54..34bddb6c1c 100644
--- a/plugins/core.c
+++ b/plugins/core.c
@@ -364,14 +364,15 @@ void plugin_register_dyn_cb__udata(GArray **arr,
enum qemu_plugin_cb_flags flags,
void *udata)
{
- static TCGHelperInfo info[3] = {
+ static TCGHelperInfo info[4] = {
[QEMU_PLUGIN_CB_NO_REGS].flags = TCG_CALL_NO_RWG,
[QEMU_PLUGIN_CB_R_REGS].flags = TCG_CALL_NO_WG,
+ [QEMU_PLUGIN_CB_RW_REGS].flags = 0,
/*
* Match qemu_plugin_vcpu_udata_cb_t:
* void (*)(uint32_t, void *)
*/
- [0 ... 2].typemask = (dh_typemask(void, 0) |
+ [0 ... 3].typemask = (dh_typemask(void, 0) |
dh_typemask(i32, 1) |
dh_typemask(ptr, 2))
};
@@ -393,14 +394,15 @@ void plugin_register_dyn_cond_cb__udata(GArray **arr,
uint64_t imm,
void *udata)
{
- static TCGHelperInfo info[3] = {
+ static TCGHelperInfo info[4] = {
[QEMU_PLUGIN_CB_NO_REGS].flags = TCG_CALL_NO_RWG,
[QEMU_PLUGIN_CB_R_REGS].flags = TCG_CALL_NO_WG,
+ [QEMU_PLUGIN_CB_RW_REGS].flags = 0,
/*
* Match qemu_plugin_vcpu_udata_cb_t:
* void (*)(uint32_t, void *)
*/
- [0 ... 2].typemask = (dh_typemask(void, 0) |
+ [0 ... 3].typemask = (dh_typemask(void, 0) |
dh_typemask(i32, 1) |
dh_typemask(ptr, 2))
};
@@ -431,14 +433,15 @@ void plugin_register_vcpu_mem_cb(GArray **arr,
!__builtin_types_compatible_p(qemu_plugin_meminfo_t, uint32_t) &&
!__builtin_types_compatible_p(qemu_plugin_meminfo_t, int32_t));
- static TCGHelperInfo info[3] = {
+ static TCGHelperInfo info[4] = {
[QEMU_PLUGIN_CB_NO_REGS].flags = TCG_CALL_NO_RWG,
[QEMU_PLUGIN_CB_R_REGS].flags = TCG_CALL_NO_WG,
+ [QEMU_PLUGIN_CB_RW_REGS].flags = 0,
/*
* Match qemu_plugin_vcpu_mem_cb_t:
* void (*)(uint32_t, qemu_plugin_meminfo_t, uint64_t, void *)
*/
- [0 ... 2].typemask =
+ [0 ... 3].typemask =
(dh_typemask(void, 0) |
dh_typemask(i32, 1) |
(__builtin_types_compatible_p(qemu_plugin_meminfo_t, uint32_t)
@@ -760,3 +763,20 @@ void plugin_scoreboard_free(struct qemu_plugin_scoreboard *score)
g_array_free(score->data, TRUE);
g_free(score);
}
+
+enum qemu_plugin_cb_flags tcg_call_to_qemu_plugin_cb_flags(int flags)
+{
+ if (flags & TCG_CALL_NO_RWG) {
+ return QEMU_PLUGIN_CB_NO_REGS;
+ } else if (flags & TCG_CALL_NO_WG) {
+ return QEMU_PLUGIN_CB_R_REGS;
+ } else {
+ return QEMU_PLUGIN_CB_RW_REGS;
+ }
+}
+
+enum qemu_plugin_cb_flags qemu_plugin_get_cb_flags(void)
+{
+ assert(current_cpu);
+ return current_cpu->neg.plugin_cb_flags;
+}
--
2.49.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH v6 4/9] plugins: Add memory virtual address write API
2025-06-02 6:08 [PATCH v6 0/9] Add additional plugin API functions to read and write memory and registers Rowan Hart
` (2 preceding siblings ...)
2025-06-02 6:08 ` [PATCH v6 3/9] plugins: Add enforcement of QEMU_PLUGIN_CB flags in register R/W callbacks Rowan Hart
@ 2025-06-02 6:08 ` Rowan Hart
2025-06-02 6:08 ` [PATCH v6 5/9] plugins: Add memory hardware address read/write API Rowan Hart
` (4 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: Rowan Hart @ 2025-06-02 6:08 UTC (permalink / raw)
To: qemu-devel
Cc: Yanan Wang, Richard Henderson, Alexandre Iooss, Zhao Liu,
Eduardo Habkost, Mahmoud Mandour, Alex Bennée,
Pierrick Bouvier, Philippe Mathieu-Daudé, Paolo Bonzini,
Marcel Apfelbaum, novafacing
From: novafacing <rowanbhart@gmail.com>
This patch adds functions to the plugins API to allow reading and
writing memory via virtual addresses. These functions only permit doing
so on the current CPU, because there is no way to ensure consistency if
plugins are allowed to read or write to other CPUs that aren't currently
in the context of the plugin.
Signed-off-by: novafacing <rowanbhart@gmail.com>
Signed-off-by: Rowan Hart <rowanbhart@gmail.com>
---
include/qemu/qemu-plugin.h | 21 +++++++++++++++++++++
plugins/api.c | 18 ++++++++++++++++++
2 files changed, 39 insertions(+)
diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
index 120fb626a6..8ae7758b95 100644
--- a/include/qemu/qemu-plugin.h
+++ b/include/qemu/qemu-plugin.h
@@ -948,6 +948,27 @@ QEMU_PLUGIN_API
bool qemu_plugin_read_memory_vaddr(uint64_t addr,
GByteArray *data, size_t len);
+/**
+ * qemu_plugin_write_memory_vaddr() - write to memory using a virtual address
+ *
+ * @addr: A virtual address to write to
+ * @data: A byte array containing the data to write
+ *
+ * The contents of @data will be written to memory starting at the virtual
+ * address @addr.
+ *
+ * This function does not guarantee consistency of writes, nor does it ensure
+ * that pending writes are flushed either before or after the write takes place,
+ * so callers should take care to only call this function in vCPU context (i.e.
+ * in callbacks) and avoid depending on the existence of data written using this
+ * function which may be overwritten afterward.
+ *
+ * Returns true on success and false on failure.
+ */
+QEMU_PLUGIN_API
+bool qemu_plugin_write_memory_vaddr(uint64_t addr,
+ GByteArray *data);
+
/**
* qemu_plugin_scoreboard_new() - alloc a new scoreboard
*
diff --git a/plugins/api.c b/plugins/api.c
index 16141f5c25..7258b6590b 100644
--- a/plugins/api.c
+++ b/plugins/api.c
@@ -476,6 +476,24 @@ bool qemu_plugin_read_memory_vaddr(uint64_t addr, GByteArray *data, size_t len)
return true;
}
+bool qemu_plugin_write_memory_vaddr(uint64_t addr, GByteArray *data)
+{
+ g_assert(current_cpu);
+
+ if (data->len == 0) {
+ return false;
+ }
+
+ int result = cpu_memory_rw_debug(current_cpu, addr, data->data,
+ data->len, true);
+
+ if (result < 0) {
+ return false;
+ }
+
+ return true;
+}
+
struct qemu_plugin_scoreboard *qemu_plugin_scoreboard_new(size_t element_size)
{
return plugin_scoreboard_new(element_size);
--
2.49.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH v6 5/9] plugins: Add memory hardware address read/write API
2025-06-02 6:08 [PATCH v6 0/9] Add additional plugin API functions to read and write memory and registers Rowan Hart
` (3 preceding siblings ...)
2025-06-02 6:08 ` [PATCH v6 4/9] plugins: Add memory virtual address write API Rowan Hart
@ 2025-06-02 6:08 ` Rowan Hart
2025-06-02 6:08 ` [PATCH v6 6/9] plugins: Add patcher plugin and test Rowan Hart
` (3 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: Rowan Hart @ 2025-06-02 6:08 UTC (permalink / raw)
To: qemu-devel
Cc: Yanan Wang, Richard Henderson, Alexandre Iooss, Zhao Liu,
Eduardo Habkost, Mahmoud Mandour, Alex Bennée,
Pierrick Bouvier, Philippe Mathieu-Daudé, Paolo Bonzini,
Marcel Apfelbaum, novafacing
From: novafacing <rowanbhart@gmail.com>
This patch adds functions to the plugins API to allow plugins to read
and write memory via hardware addresses. The functions use the current
address space of the current CPU in order to avoid exposing address
space information to users. A later patch may want to add a function to
permit a specified address space, for example to facilitate
architecture-specific plugins that want to operate on them, for example
reading ARM secure memory.
Signed-off-by: novafacing <rowanbhart@gmail.com>
Signed-off-by: Rowan Hart <rowanbhart@gmail.com>
---
include/qemu/qemu-plugin.h | 93 ++++++++++++++++++++++++++++++++++++
plugins/api.c | 97 ++++++++++++++++++++++++++++++++++++++
2 files changed, 190 insertions(+)
diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
index 8ae7758b95..2cb5de9f64 100644
--- a/include/qemu/qemu-plugin.h
+++ b/include/qemu/qemu-plugin.h
@@ -969,6 +969,99 @@ QEMU_PLUGIN_API
bool qemu_plugin_write_memory_vaddr(uint64_t addr,
GByteArray *data);
+/**
+ * enum qemu_plugin_hwaddr_operation_result - result of a memory operation
+ *
+ * @QEMU_PLUGIN_HWADDR_OPERATION_OK: hwaddr operation succeeded
+ * @QEMU_PLUGIN_HWADDR_OPERATION_ERROR: unexpected error occurred
+ * @QEMU_PLUGIN_HWADDR_OPERATION_DEVICE_ERROR: error in memory device
+ * @QEMU_PLUGIN_HWADDR_OPERATION_ACCESS_DENIED: permission error
+ * @QEMU_PLUGIN_HWADDR_OPERATION_INVALID_ADDRESS: address was invalid
+ * @QEMU_PLUGIN_HWADDR_OPERATION_INVALID_ADDRESS_SPACE: invalid address space
+ */
+enum qemu_plugin_hwaddr_operation_result {
+ QEMU_PLUGIN_HWADDR_OPERATION_OK,
+ QEMU_PLUGIN_HWADDR_OPERATION_ERROR,
+ QEMU_PLUGIN_HWADDR_OPERATION_DEVICE_ERROR,
+ QEMU_PLUGIN_HWADDR_OPERATION_ACCESS_DENIED,
+ QEMU_PLUGIN_HWADDR_OPERATION_INVALID_ADDRESS,
+ QEMU_PLUGIN_HWADDR_OPERATION_INVALID_ADDRESS_SPACE,
+};
+
+/**
+ * qemu_plugin_read_memory_hwaddr() - read from memory using a hardware address
+ *
+ * @addr: The physical address to read from
+ * @data: A byte array to store data into
+ * @len: The number of bytes to read, starting from @addr
+ *
+ * @len bytes of data is read from the current memory space for the current
+ * vCPU starting at @addr and stored into @data. If @data is not large enough to
+ * hold @len bytes, it will be expanded to the necessary size, reallocating if
+ * necessary. @len must be greater than 0.
+ *
+ * This function does not ensure writes are flushed prior to reading, so
+ * callers should take care when calling this function in plugin callbacks to
+ * avoid attempting to read data which may not yet be written and should use
+ * the memory callback API instead.
+ *
+ * This function is only valid for softmmu targets.
+ *
+ * Returns a qemu_plugin_hwaddr_operation_result indicating the result of the
+ * operation.
+ */
+QEMU_PLUGIN_API
+enum qemu_plugin_hwaddr_operation_result
+qemu_plugin_read_memory_hwaddr(uint64_t addr, GByteArray *data, size_t len);
+
+/**
+ * qemu_plugin_write_memory_hwaddr() - write to memory using a hardware address
+ *
+ * @addr: A physical address to write to
+ * @data: A byte array containing the data to write
+ *
+ * The contents of @data will be written to memory starting at the hardware
+ * address @addr in the current address space for the current vCPU.
+ *
+ * This function does not guarantee consistency of writes, nor does it ensure
+ * that pending writes are flushed either before or after the write takes place,
+ * so callers should take care when calling this function in plugin callbacks to
+ * avoid depending on the existence of data written using this function which
+ * may be overwritten afterward. In addition, this function requires that the
+ * pages containing the address are not locked. Practically, this means that you
+ * should not write instruction memory in a current translation block inside a
+ * callback registered with qemu_plugin_register_vcpu_tb_trans_cb.
+ *
+ * You can, for example, write instruction memory in a current translation block
+ * in a callback registered with qemu_plugin_register_vcpu_tb_exec_cb, although
+ * be aware that the write will not be flushed until after the translation block
+ * has finished executing. In general, this function should be used to write
+ * data memory or to patch code at a known address, not in a current translation
+ * block.
+ *
+ * This function is only valid for softmmu targets.
+ *
+ * Returns a qemu_plugin_hwaddr_operation_result indicating the result of the
+ * operation.
+ */
+QEMU_PLUGIN_API
+enum qemu_plugin_hwaddr_operation_result
+qemu_plugin_write_memory_hwaddr(uint64_t addr, GByteArray *data);
+
+/**
+ * qemu_plugin_translate_vaddr() - translate virtual address for current vCPU
+ *
+ * @vaddr: virtual address to translate
+ * @hwaddr: pointer to store the physical address
+ *
+ * This function is only valid in vCPU context (i.e. in callbacks) and is only
+ * valid for softmmu targets.
+ *
+ * Returns true on success and false on failure.
+ */
+QEMU_PLUGIN_API
+bool qemu_plugin_translate_vaddr(uint64_t vaddr, uint64_t *hwaddr);
+
/**
* qemu_plugin_scoreboard_new() - alloc a new scoreboard
*
diff --git a/plugins/api.c b/plugins/api.c
index 7258b6590b..a0d980e113 100644
--- a/plugins/api.c
+++ b/plugins/api.c
@@ -39,6 +39,7 @@
#include "qemu/main-loop.h"
#include "qemu/plugin.h"
#include "qemu/log.h"
+#include "system/memory.h"
#include "tcg/tcg.h"
#include "exec/gdbstub.h"
#include "exec/target_page.h"
@@ -494,6 +495,102 @@ bool qemu_plugin_write_memory_vaddr(uint64_t addr, GByteArray *data)
return true;
}
+enum qemu_plugin_hwaddr_operation_result
+qemu_plugin_read_memory_hwaddr(hwaddr addr, GByteArray *data, size_t len)
+{
+#ifdef CONFIG_SOFTMMU
+ if (len == 0) {
+ return QEMU_PLUGIN_HWADDR_OPERATION_ERROR;
+ }
+
+ g_assert(current_cpu);
+
+
+ int as_idx = cpu_asidx_from_attrs(current_cpu, MEMTXATTRS_UNSPECIFIED);
+ AddressSpace *as = cpu_get_address_space(current_cpu, as_idx);
+
+ if (as == NULL) {
+ return QEMU_PLUGIN_HWADDR_OPERATION_INVALID_ADDRESS_SPACE;
+ }
+
+ g_byte_array_set_size(data, len);
+ MemTxResult res = address_space_rw(as, addr,
+ MEMTXATTRS_UNSPECIFIED, data->data,
+ data->len, false);
+
+ switch (res) {
+ case MEMTX_OK:
+ return QEMU_PLUGIN_HWADDR_OPERATION_OK;
+ case MEMTX_ERROR:
+ return QEMU_PLUGIN_HWADDR_OPERATION_DEVICE_ERROR;
+ case MEMTX_DECODE_ERROR:
+ return QEMU_PLUGIN_HWADDR_OPERATION_INVALID_ADDRESS;
+ case MEMTX_ACCESS_ERROR:
+ return QEMU_PLUGIN_HWADDR_OPERATION_ACCESS_DENIED;
+ default:
+ return QEMU_PLUGIN_HWADDR_OPERATION_ERROR;
+ }
+#else
+ return QEMU_PLUGIN_HWADDR_OPERATION_ERROR;
+#endif
+}
+
+enum qemu_plugin_hwaddr_operation_result
+qemu_plugin_write_memory_hwaddr(hwaddr addr, GByteArray *data)
+{
+#ifdef CONFIG_SOFTMMU
+ if (data->len == 0) {
+ return QEMU_PLUGIN_HWADDR_OPERATION_ERROR;
+ }
+
+ g_assert(current_cpu);
+
+ int as_idx = cpu_asidx_from_attrs(current_cpu, MEMTXATTRS_UNSPECIFIED);
+ AddressSpace *as = cpu_get_address_space(current_cpu, as_idx);
+
+ if (as == NULL) {
+ return QEMU_PLUGIN_HWADDR_OPERATION_INVALID_ADDRESS_SPACE;
+ }
+
+ MemTxResult res = address_space_rw(as, addr,
+ MEMTXATTRS_UNSPECIFIED, data->data,
+ data->len, true);
+ switch (res) {
+ case MEMTX_OK:
+ return QEMU_PLUGIN_HWADDR_OPERATION_OK;
+ case MEMTX_ERROR:
+ return QEMU_PLUGIN_HWADDR_OPERATION_DEVICE_ERROR;
+ case MEMTX_DECODE_ERROR:
+ return QEMU_PLUGIN_HWADDR_OPERATION_INVALID_ADDRESS;
+ case MEMTX_ACCESS_ERROR:
+ return QEMU_PLUGIN_HWADDR_OPERATION_ACCESS_DENIED;
+ default:
+ return QEMU_PLUGIN_HWADDR_OPERATION_ERROR;
+ }
+#else
+ return QEMU_PLUGIN_HWADDR_OPERATION_ERROR;
+#endif
+}
+
+bool qemu_plugin_translate_vaddr(uint64_t vaddr, uint64_t *hwaddr)
+{
+#ifdef CONFIG_SOFTMMU
+ g_assert(current_cpu);
+
+ uint64_t res = cpu_get_phys_page_debug(current_cpu, vaddr);
+
+ if (res == (uint64_t)-1) {
+ return false;
+ }
+
+ *hwaddr = res | (vaddr & ~TARGET_PAGE_MASK);
+
+ return true;
+#else
+ return false;
+#endif
+}
+
struct qemu_plugin_scoreboard *qemu_plugin_scoreboard_new(size_t element_size)
{
return plugin_scoreboard_new(element_size);
--
2.49.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH v6 6/9] plugins: Add patcher plugin and test
2025-06-02 6:08 [PATCH v6 0/9] Add additional plugin API functions to read and write memory and registers Rowan Hart
` (4 preceding siblings ...)
2025-06-02 6:08 ` [PATCH v6 5/9] plugins: Add memory hardware address read/write API Rowan Hart
@ 2025-06-02 6:08 ` Rowan Hart
2025-06-02 6:08 ` [PATCH v6 7/9] plugins: Add hypercalls " Rowan Hart
` (2 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: Rowan Hart @ 2025-06-02 6:08 UTC (permalink / raw)
To: qemu-devel
Cc: Yanan Wang, Richard Henderson, Alexandre Iooss, Zhao Liu,
Eduardo Habkost, Mahmoud Mandour, Alex Bennée,
Pierrick Bouvier, Philippe Mathieu-Daudé, Paolo Bonzini,
Marcel Apfelbaum, novafacing
From: novafacing <rowanbhart@gmail.com>
This patch adds a plugin that exercises the virtual and hardware memory
read-write API functions added in a previous patch. The plugin takes a
target and patch byte sequence, and will overwrite any instruction
matching the target byte sequence with the patch.
Signed-off-by: novafacing <rowanbhart@gmail.com>
Signed-off-by: Rowan Hart <rowanbhart@gmail.com>
---
tests/tcg/Makefile.target | 1 +
tests/tcg/plugins/meson.build | 2 +-
tests/tcg/plugins/patch.c | 297 ++++++++++++++++++++++
tests/tcg/x86_64/Makefile.softmmu-target | 32 ++-
tests/tcg/x86_64/system/patch-target.c | 27 ++
tests/tcg/x86_64/system/validate-patch.py | 39 +++
6 files changed, 392 insertions(+), 6 deletions(-)
create mode 100644 tests/tcg/plugins/patch.c
create mode 100644 tests/tcg/x86_64/system/patch-target.c
create mode 100755 tests/tcg/x86_64/system/validate-patch.py
diff --git a/tests/tcg/Makefile.target b/tests/tcg/Makefile.target
index 95ff76ea44..4b709a9d18 100644
--- a/tests/tcg/Makefile.target
+++ b/tests/tcg/Makefile.target
@@ -176,6 +176,7 @@ RUN_TESTS+=$(EXTRA_RUNS)
# Some plugins need additional arguments above the default to fully
# exercise things. We can define them on a per-test basis here.
run-plugin-%-with-libmem.so: PLUGIN_ARGS=$(COMMA)inline=true
+run-plugin-%-with-libpatch.so: PLUGIN_ARGS=$(COMMA)target=ffffffff$(COMMA)patch=00000000
ifeq ($(filter %-softmmu, $(TARGET)),)
run-%: %
diff --git a/tests/tcg/plugins/meson.build b/tests/tcg/plugins/meson.build
index 41f02f2c7f..163042e601 100644
--- a/tests/tcg/plugins/meson.build
+++ b/tests/tcg/plugins/meson.build
@@ -1,6 +1,6 @@
t = []
if get_option('plugins')
- foreach i : ['bb', 'empty', 'inline', 'insn', 'mem', 'reset', 'syscall']
+ foreach i : ['bb', 'empty', 'inline', 'insn', 'mem', 'reset', 'syscall', 'patch']
if host_os == 'windows'
t += shared_module(i, files(i + '.c') + '../../../contrib/plugins/win32_linker.c',
include_directories: '../../../include/qemu',
diff --git a/tests/tcg/plugins/patch.c b/tests/tcg/plugins/patch.c
new file mode 100644
index 0000000000..6e83418b85
--- /dev/null
+++ b/tests/tcg/plugins/patch.c
@@ -0,0 +1,297 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This plugin patches instructions matching a pattern to a different
+ * instruction as they execute
+ *
+ */
+
+#include "glib.h"
+#include "glibconfig.h"
+
+#include <qemu-plugin.h>
+#include <string.h>
+#include <stdio.h>
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
+
+static bool use_hwaddr;
+static bool debug_insns;
+static GByteArray *target_data;
+static GByteArray *patch_data;
+
+/**
+ * Parse a string of hexadecimal digits into a GByteArray. The string must be
+ * even length
+ */
+static GByteArray *str_to_bytes(const char *str)
+{
+ GByteArray *bytes = g_byte_array_new();
+ char byte[3] = {0};
+ size_t len = strlen(str);
+ guint8 value = 0;
+
+ if (len % 2 != 0) {
+ g_byte_array_free(bytes, true);
+ return NULL;
+ }
+
+ for (size_t i = 0; i < len; i += 2) {
+ byte[0] = str[i];
+ byte[1] = str[i + 1];
+ value = (guint8)g_ascii_strtoull(byte, NULL, 16);
+ g_byte_array_append(bytes, &value, 1);
+ }
+
+ return bytes;
+}
+
+static void patch_hwaddr(unsigned int vcpu_index, void *userdata)
+{
+ uint64_t addr = (uint64_t)userdata;
+ GString *str = g_string_new(NULL);
+ g_string_printf(str, "patching: @0x%"
+ PRIx64 "\n",
+ addr);
+ qemu_plugin_outs(str->str);
+ g_string_free(str, true);
+
+ enum qemu_plugin_hwaddr_operation_result result =
+ qemu_plugin_write_memory_hwaddr(addr, patch_data);
+
+
+ if (result != QEMU_PLUGIN_HWADDR_OPERATION_OK) {
+ GString *errmsg = g_string_new(NULL);
+ g_string_printf(errmsg, "Failed to write memory: %d\n", result);
+ qemu_plugin_outs(errmsg->str);
+ g_string_free(errmsg, true);
+ return;
+ }
+
+ GByteArray *read_data = g_byte_array_new();
+
+ result = qemu_plugin_read_memory_hwaddr(addr, read_data,
+ patch_data->len);
+
+ qemu_plugin_outs("Reading memory...\n");
+
+ if (result != QEMU_PLUGIN_HWADDR_OPERATION_OK) {
+ GString *errmsg = g_string_new(NULL);
+ g_string_printf(errmsg, "Failed to read memory: %d\n", result);
+ qemu_plugin_outs(errmsg->str);
+ g_string_free(errmsg, true);
+ return;
+ }
+
+ if (memcmp(patch_data->data, read_data->data, patch_data->len) != 0) {
+ qemu_plugin_outs("Failed to read back written data\n");
+ }
+
+ qemu_plugin_outs("Success!\n");
+
+ return;
+}
+
+static void patch_vaddr(unsigned int vcpu_index, void *userdata)
+{
+ uint64_t addr = (uint64_t)userdata;
+ uint64_t hwaddr = 0;
+ if (!qemu_plugin_translate_vaddr(addr, &hwaddr)) {
+ qemu_plugin_outs("Failed to translate vaddr\n");
+ return;
+ }
+ GString *str = g_string_new(NULL);
+ g_string_printf(str, "patching: @0x%"
+ PRIx64 " hw: @0x%" PRIx64 "\n",
+ addr, hwaddr);
+ qemu_plugin_outs(str->str);
+ g_string_free(str, true);
+
+ qemu_plugin_outs("Writing memory (vaddr)...\n");
+
+ if (!qemu_plugin_write_memory_vaddr(addr, patch_data)) {
+ qemu_plugin_outs("Failed to write memory\n");
+ return;
+ }
+
+ qemu_plugin_outs("Reading memory (vaddr)...\n");
+
+
+ GByteArray *read_data = g_byte_array_new();
+
+ if (!qemu_plugin_read_memory_vaddr(addr, read_data, patch_data->len)) {
+ qemu_plugin_outs("Failed to read memory\n");
+ return;
+ }
+
+ if (memcmp(patch_data->data, read_data->data, patch_data->len) != 0) {
+ qemu_plugin_outs("Failed to read back written data\n");
+ }
+
+ qemu_plugin_outs("Success!\n");
+
+ return;
+}
+
+static void debug_disas(unsigned int vcpu_index, void *userdata)
+{
+ GString *debug_info = (GString *)userdata;
+ qemu_plugin_outs(debug_info->str);
+}
+
+static void debug_print_newline(unsigned int vcpu_index, void *userdata)
+{
+ qemu_plugin_outs("\n");
+}
+
+/*
+ * Callback on translation of a translation block.
+ */
+static void vcpu_tb_trans_cb(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
+{
+ uint64_t addr = 0;
+ GByteArray *insn_data = g_byte_array_new();
+ for (size_t i = 0; i < qemu_plugin_tb_n_insns(tb); i++) {
+ struct qemu_plugin_insn *insn = qemu_plugin_tb_get_insn(tb, i);
+
+ if (use_hwaddr) {
+ uint64_t vaddr = qemu_plugin_insn_vaddr(insn);
+ if (!qemu_plugin_translate_vaddr(vaddr, &addr)) {
+ qemu_plugin_outs("Failed to translate vaddr\n");
+ continue;
+ }
+ } else {
+ addr = qemu_plugin_insn_vaddr(insn);
+ }
+
+ g_byte_array_set_size(insn_data, qemu_plugin_insn_size(insn));
+ qemu_plugin_insn_data(insn, insn_data->data, insn_data->len);
+
+ if (insn_data->len >= target_data->len &&
+ !memcmp(insn_data->data, target_data->data,
+ MIN(target_data->len, insn_data->len))) {
+ if (use_hwaddr) {
+ qemu_plugin_register_vcpu_tb_exec_cb(tb, patch_hwaddr,
+ QEMU_PLUGIN_CB_NO_REGS,
+ (void *)addr);
+ } else {
+ qemu_plugin_register_vcpu_tb_exec_cb(tb, patch_vaddr,
+ QEMU_PLUGIN_CB_NO_REGS,
+ (void *)addr);
+ }
+ }
+ }
+ for (size_t i = 0; i < qemu_plugin_tb_n_insns(tb); i++) {
+ struct qemu_plugin_insn *insn = qemu_plugin_tb_get_insn(tb, i);
+ uint64_t vaddr = qemu_plugin_insn_vaddr(insn);
+ uint64_t hwaddr = (uint64_t)qemu_plugin_insn_haddr(insn);
+ uint64_t translated_hwaddr = 0;
+ if (!qemu_plugin_translate_vaddr(vaddr, &translated_hwaddr)) {
+ qemu_plugin_outs("Failed to translate vaddr\n");
+ continue;
+ }
+ char *disas = qemu_plugin_insn_disas(insn);
+ GString *str = g_string_new(NULL);
+ g_string_printf(str,
+ "vaddr: 0x%" PRIx64 " hwaddr: 0x%" PRIx64
+ " translated: 0x%" PRIx64 " : %s\n",
+ vaddr, hwaddr, translated_hwaddr, disas);
+ g_free(disas);
+ if (debug_insns) {
+ qemu_plugin_register_vcpu_insn_exec_cb(insn, debug_disas,
+ QEMU_PLUGIN_CB_NO_REGS,
+ str);
+ }
+
+ }
+
+ if (debug_insns) {
+ qemu_plugin_register_vcpu_tb_exec_cb(tb, debug_print_newline,
+ QEMU_PLUGIN_CB_NO_REGS,
+ NULL);
+ }
+
+ g_byte_array_free(insn_data, true);
+}
+
+static void usage(void)
+{
+ fprintf(stderr, "Usage: <lib>,target=<target>,patch=<patch>"
+ "[,use_hwaddr=<use_hwaddr>]"
+ "[,debug_insns=<debug_insns>]\n");
+}
+
+/*
+ * Called when the plugin is installed
+ */
+QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
+ const qemu_info_t *info, int argc,
+ char **argv)
+{
+
+ use_hwaddr = true;
+ debug_insns = false;
+ target_data = NULL;
+ patch_data = NULL;
+
+ if (argc > 4) {
+ usage();
+ return -1;
+ }
+
+ for (size_t i = 0; i < argc; i++) {
+ char *opt = argv[i];
+ g_auto(GStrv) tokens = g_strsplit(opt, "=", 2);
+ if (g_strcmp0(tokens[0], "use_hwaddr") == 0) {
+ if (!qemu_plugin_bool_parse(tokens[0], tokens[1], &use_hwaddr)) {
+ fprintf(stderr,
+ "Failed to parse boolean argument use_hwaddr\n");
+ return -1;
+ }
+ } else if (g_strcmp0(tokens[0], "debug_insns") == 0) {
+ if (!qemu_plugin_bool_parse(tokens[0], tokens[1], &debug_insns)) {
+ fprintf(stderr,
+ "Failed to parse boolean argument debug_insns\n");
+ return -1;
+ }
+ } else if (g_strcmp0(tokens[0], "target") == 0) {
+ target_data = str_to_bytes(tokens[1]);
+ if (!target_data) {
+ fprintf(stderr,
+ "Failed to parse target bytes.\n");
+ return -1;
+ }
+ } else if (g_strcmp0(tokens[0], "patch") == 0) {
+ patch_data = str_to_bytes(tokens[1]);
+ if (!patch_data) {
+ fprintf(stderr, "Failed to parse patch bytes.\n");
+ return -1;
+ }
+ } else {
+ fprintf(stderr, "Unknown argument: %s\n", tokens[0]);
+ usage();
+ return -1;
+ }
+ }
+
+ if (!target_data) {
+ fprintf(stderr, "target argument is required\n");
+ usage();
+ return -1;
+ }
+
+ if (!patch_data) {
+ fprintf(stderr, "patch argument is required\n");
+ usage();
+ return -1;
+ }
+
+ if (target_data->len != patch_data->len) {
+ fprintf(stderr, "Target and patch data must be the same length\n");
+ return -1;
+ }
+
+ qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans_cb);
+
+ return 0;
+}
diff --git a/tests/tcg/x86_64/Makefile.softmmu-target b/tests/tcg/x86_64/Makefile.softmmu-target
index ef6bcb4dc7..8d3a067c33 100644
--- a/tests/tcg/x86_64/Makefile.softmmu-target
+++ b/tests/tcg/x86_64/Makefile.softmmu-target
@@ -7,18 +7,27 @@
#
I386_SYSTEM_SRC=$(SRC_PATH)/tests/tcg/i386/system
-X64_SYSTEM_SRC=$(SRC_PATH)/tests/tcg/x86_64/system
+X86_64_SYSTEM_SRC=$(SRC_PATH)/tests/tcg/x86_64/system
# These objects provide the basic boot code and helper functions for all tests
CRT_OBJS=boot.o
-CRT_PATH=$(X64_SYSTEM_SRC)
-LINK_SCRIPT=$(X64_SYSTEM_SRC)/kernel.ld
+X86_64_TEST_C_SRCS=$(wildcard $(X86_64_SYSTEM_SRC)/*.c)
+X86_64_TEST_S_SRCS=
+
+X86_64_C_TESTS = $(patsubst $(X86_64_SYSTEM_SRC)/%.c, %, $(X86_64_TEST_C_SRCS))
+X86_64_S_TESTS = $(patsubst $(X86_64_SYSTEM_SRC)/%.S, %, $(X86_64_TEST_S_SRCS))
+
+X86_64_TESTS = $(X86_64_C_TESTS)
+X86_64_TESTS += $(X86_64_S_TESTS)
+
+CRT_PATH=$(X86_64_SYSTEM_SRC)
+LINK_SCRIPT=$(X86_64_SYSTEM_SRC)/kernel.ld
LDFLAGS=-Wl,-T$(LINK_SCRIPT) -Wl,-melf_x86_64
CFLAGS+=-nostdlib -ggdb -O0 $(MINILIB_INC)
LDFLAGS+=-static -nostdlib $(CRT_OBJS) $(MINILIB_OBJS) -lgcc
-TESTS+=$(MULTIARCH_TESTS)
+TESTS+=$(X86_64_TESTS) $(MULTIARCH_TESTS)
EXTRA_RUNS+=$(MULTIARCH_RUNS)
# building head blobs
@@ -27,11 +36,24 @@ EXTRA_RUNS+=$(MULTIARCH_RUNS)
%.o: $(CRT_PATH)/%.S
$(CC) $(CFLAGS) $(EXTRA_CFLAGS) -Wa,--noexecstack -c $< -o $@
-# Build and link the tests
+# Build and link the multiarch tests
%: %.c $(LINK_SCRIPT) $(CRT_OBJS) $(MINILIB_OBJS)
$(CC) $(CFLAGS) $(EXTRA_CFLAGS) $< -o $@ $(LDFLAGS)
+# Build and link the arch tests
+%: $(X86_64_SYSTEM_SRC)/%.c $(LINK_SCRIPT) $(CRT_OBJS) $(MINILIB_OBJS)
+ $(CC) $(CFLAGS) $(EXTRA_CFLAGS) $< -o $@ $(LDFLAGS)
+
memory: CFLAGS+=-DCHECK_UNALIGNED=1
+patch-target: CFLAGS+=-O0
# Running
QEMU_OPTS+=-device isa-debugcon,chardev=output -device isa-debug-exit,iobase=0xf4,iosize=0x4 -kernel
+
+# Add patch-target to ADDITIONAL_PLUGINS_TESTS
+ADDITIONAL_PLUGINS_TESTS += patch-target
+
+run-plugin-patch-target-with-libpatch.so: \
+ PLUGIN_ARGS=$(COMMA)target=ffc0$(COMMA)patch=9090$(COMMA)use_hwaddr=true$(COMMA)debug_insns=false
+run-plugin-patch-target-with-libpatch.so: \
+ CHECK_PLUGIN_OUTPUT_COMMAND=$(X86_64_SYSTEM_SRC)/validate-patch.py $@.out
\ No newline at end of file
diff --git a/tests/tcg/x86_64/system/patch-target.c b/tests/tcg/x86_64/system/patch-target.c
new file mode 100644
index 0000000000..8a7c0a0ae8
--- /dev/null
+++ b/tests/tcg/x86_64/system/patch-target.c
@@ -0,0 +1,27 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This test target increments a value 100 times. The patcher converts the
+ * inc instruction to a nop, so it only increments the value once.
+ *
+ */
+#include <minilib.h>
+
+int main(void)
+{
+ ml_printf("Running test...\n");
+#if defined(__x86_64__)
+ ml_printf("Testing insn memory read/write...\n");
+ unsigned int x = 0;
+ for (int i = 0; i < 100; i++) {
+ asm volatile (
+ "inc %[x]"
+ : [x] "+a" (x)
+ );
+ }
+ ml_printf("Value: %d\n", x);
+#else
+ #error "This test is only valid for x86_64 architecture."
+#endif
+ return 0;
+}
diff --git a/tests/tcg/x86_64/system/validate-patch.py b/tests/tcg/x86_64/system/validate-patch.py
new file mode 100755
index 0000000000..700950eae5
--- /dev/null
+++ b/tests/tcg/x86_64/system/validate-patch.py
@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+#
+# validate-patch.py: check the patch applies
+#
+# This program takes two inputs:
+# - the plugin output
+# - the binary output
+#
+# Copyright (C) 2024
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+import sys
+from argparse import ArgumentParser
+
+def main() -> None:
+ """
+ Process the arguments, injest the program and plugin out and
+ verify they match up and report if they do not.
+ """
+ parser = ArgumentParser(description="Validate patch")
+ parser.add_argument('test_output',
+ help="The output from the test itself")
+ parser.add_argument('plugin_output',
+ help="The output from plugin")
+ args = parser.parse_args()
+
+ with open(args.test_output, 'r') as f:
+ test_data = f.read()
+ with open(args.plugin_output, 'r') as f:
+ plugin_data = f.read()
+ if "Value: 1" in test_data:
+ sys.exit(0)
+ else:
+ sys.exit(1)
+
+if __name__ == "__main__":
+ main()
+
--
2.49.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH v6 7/9] plugins: Add hypercalls plugin and test
2025-06-02 6:08 [PATCH v6 0/9] Add additional plugin API functions to read and write memory and registers Rowan Hart
` (5 preceding siblings ...)
2025-06-02 6:08 ` [PATCH v6 6/9] plugins: Add patcher plugin and test Rowan Hart
@ 2025-06-02 6:08 ` Rowan Hart
2025-06-02 6:08 ` [PATCH v6 8/9] plugins: Remove use of qemu_plugin_read_register where it is not permitted Rowan Hart
2025-06-02 6:08 ` [PATCH v6 9/9] plugins: Update plugin version and add notes Rowan Hart
8 siblings, 0 replies; 10+ messages in thread
From: Rowan Hart @ 2025-06-02 6:08 UTC (permalink / raw)
To: qemu-devel
Cc: Yanan Wang, Richard Henderson, Alexandre Iooss, Zhao Liu,
Eduardo Habkost, Mahmoud Mandour, Alex Bennée,
Pierrick Bouvier, Philippe Mathieu-Daudé, Paolo Bonzini,
Marcel Apfelbaum, novafacing
From: novafacing <rowanbhart@gmail.com>
This patch adds a plugin that implements a simple form of hypercalls
from guest code to the plugin by using the register read API. It accepts
only one hypercall, which writes a magic value to guest memory.
Signed-off-by: novafacing <rowanbhart@gmail.com>
Signed-off-by: Rowan Hart <rowanbhart@gmail.com>
---
tests/tcg/Makefile.target | 1 +
tests/tcg/plugins/hypercalls.c | 547 ++++++++++++++++++
tests/tcg/plugins/meson.build | 2 +-
tests/tcg/x86_64/Makefile.softmmu-target | 6 +-
tests/tcg/x86_64/system/hypercalls-target.c | 40 ++
.../tcg/x86_64/system/validate-hypercalls.py | 40 ++
6 files changed, 634 insertions(+), 2 deletions(-)
create mode 100644 tests/tcg/plugins/hypercalls.c
create mode 100644 tests/tcg/x86_64/system/hypercalls-target.c
create mode 100755 tests/tcg/x86_64/system/validate-hypercalls.py
diff --git a/tests/tcg/Makefile.target b/tests/tcg/Makefile.target
index 4b709a9d18..5ac9638102 100644
--- a/tests/tcg/Makefile.target
+++ b/tests/tcg/Makefile.target
@@ -177,6 +177,7 @@ RUN_TESTS+=$(EXTRA_RUNS)
# exercise things. We can define them on a per-test basis here.
run-plugin-%-with-libmem.so: PLUGIN_ARGS=$(COMMA)inline=true
run-plugin-%-with-libpatch.so: PLUGIN_ARGS=$(COMMA)target=ffffffff$(COMMA)patch=00000000
+run-plugin-%-with-libhypercalls.so: PLUGIN_ARGS=$(COMMA)ignore_unsupported=true
ifeq ($(filter %-softmmu, $(TARGET)),)
run-%: %
diff --git a/tests/tcg/plugins/hypercalls.c b/tests/tcg/plugins/hypercalls.c
new file mode 100644
index 0000000000..3214bb8ee5
--- /dev/null
+++ b/tests/tcg/plugins/hypercalls.c
@@ -0,0 +1,547 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This plugin implements a simple hypercall interface for guests (both system
+ * and user mode) to call certain operations from the host.
+ */
+#include "glib.h"
+#include "glibconfig.h"
+#include <assert.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <qemu-plugin.h>
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
+
+#define AARCH64_N_HYPERCALL_INSNS (28)
+#define AARCH64_HYPERCALL_INSN_LEN (4)
+#define AARCH64_HYPERCALL_MAX (AARCH64_N_HYPERCALL_INSNS)
+#define ARM_N_HYPERCALL_INSNS (12)
+#define ARM_HYPERCALL_INSN_LEN (4)
+#define ARM_HYPERCALL_MAX (ARM_N_HYPERCALL_INSNS)
+#define X86_HYPERCALL_INSN_LEN (2)
+#define X86_HYPERCALL_VALUE_BASE (0x4711)
+#define X86_HYPERCALL_MAX (0x10000)
+#define N_HYPERCALL_ARGS (4)
+
+static bool ignore_unsupported;
+
+static struct qemu_plugin_register *get_register(const char *name);
+static uint64_t byte_array_to_uint64(GByteArray *buf);
+
+enum HypercallInsnType {
+ CONSTANT,
+ CALLBACK,
+};
+
+
+/*
+ * Checks an instruction and returns its hypercall number, if it is
+ * a hypercall instruction, or -1 if it is not. Called at execution
+ * time.
+ */
+typedef int32_t (*hypercall_nr_cb)(GByteArray *);
+
+/*
+ * Checks an instruction and returns whether it is a hypercall, or -1 if it is
+ * not. Called at execution time.
+ */
+typedef bool (*is_hypercall_cb)(GByteArray *);
+
+/*
+ * Specifies a Hypercall for an architecture:
+ *
+ * - Architecture name
+ * - Whether it is enabled
+ * - The hypercall instruction
+ * - The register names to pass the hypercall # and args
+ */
+struct HypercallSpec {
+ const bool enabled;
+ const char *name;
+ const bool le;
+ const char *args[N_HYPERCALL_ARGS];
+ const hypercall_nr_cb hypercall_nr_cb;
+ const is_hypercall_cb is_hypercall_cb;
+};
+
+static int32_t aarch64_hypercall_nr_cb(GByteArray *insn)
+{
+ if (insn->len != AARCH64_HYPERCALL_INSN_LEN) {
+ return -1;
+ }
+
+ static const uint8_t
+ hypercall_insns[AARCH64_N_HYPERCALL_INSNS][AARCH64_HYPERCALL_INSN_LEN] = {
+ { 0xaa, 0x4, 0x0, 0x84 },
+ { 0xaa, 0x5, 0x0, 0xa5 },
+ { 0xaa, 0x6, 0x0, 0xc6 },
+ { 0xaa, 0x7, 0x0, 0xe7 },
+ { 0xaa, 0x8, 0x1, 0x8 },
+ { 0xaa, 0x9, 0x1, 0x29 },
+ { 0xaa, 0xa, 0x1, 0x4a },
+ { 0xaa, 0xb, 0x1, 0x6b },
+ { 0xaa, 0xc, 0x1, 0x8c },
+ { 0xaa, 0xd, 0x1, 0xad },
+ { 0xaa, 0xe, 0x1, 0xce },
+ { 0xaa, 0xf, 0x1, 0xef },
+ { 0xaa, 0x10, 0x2, 0x10 },
+ { 0xaa, 0x11, 0x2, 0x31 },
+ { 0xaa, 0x12, 0x2, 0x52 },
+ { 0xaa, 0x13, 0x2, 0x73 },
+ { 0xaa, 0x14, 0x2, 0x94 },
+ { 0xaa, 0x15, 0x2, 0xb5 },
+ { 0xaa, 0x16, 0x2, 0xd6 },
+ { 0xaa, 0x17, 0x2, 0xf7 },
+ { 0xaa, 0x18, 0x3, 0x18 },
+ { 0xaa, 0x19, 0x3, 0x39 },
+ { 0xaa, 0x1a, 0x3, 0x5a },
+ { 0xaa, 0x1b, 0x3, 0x7b },
+ { 0xaa, 0x1c, 0x3, 0x9c },
+ { 0xaa, 0x1d, 0x3, 0xbd },
+ { 0xaa, 0x1e, 0x3, 0xde },
+ { 0xaa, 0x1f, 0x3, 0xff },
+ };
+
+ for (int32_t i = 0; i < AARCH64_N_HYPERCALL_INSNS; i++) {
+ if (!memcmp(hypercall_insns[i], insn->data, insn->len)) {
+ return i;
+ }
+ }
+ return -1;
+}
+
+static bool aarch64_is_hypercall_cb(GByteArray *insn)
+{
+ return aarch64_hypercall_nr_cb(insn) < 0;
+}
+
+
+static int32_t aarch64_be_hypercall_nr_cb(GByteArray *insn)
+{
+ if (insn->len != AARCH64_HYPERCALL_INSN_LEN) {
+ return -1;
+ }
+
+ static const uint8_t
+ hypercall_insns[AARCH64_N_HYPERCALL_INSNS][AARCH64_HYPERCALL_INSN_LEN] = {
+ {0x84, 0x0, 0x4, 0xaa},
+ {0xa5, 0x0, 0x5, 0xaa},
+ {0xc6, 0x0, 0x6, 0xaa},
+ {0xe7, 0x0, 0x7, 0xaa},
+ {0x8, 0x1, 0x8, 0xaa},
+ {0x29, 0x1, 0x9, 0xaa},
+ {0x4a, 0x1, 0xa, 0xaa},
+ {0x6b, 0x1, 0xb, 0xaa},
+ {0x8c, 0x1, 0xc, 0xaa},
+ {0xad, 0x1, 0xd, 0xaa},
+ {0xce, 0x1, 0xe, 0xaa},
+ {0xef, 0x1, 0xf, 0xaa},
+ {0x10, 0x2, 0x10, 0xaa},
+ {0x31, 0x2, 0x11, 0xaa},
+ {0x52, 0x2, 0x12, 0xaa},
+ {0x73, 0x2, 0x13, 0xaa},
+ {0x94, 0x2, 0x14, 0xaa},
+ {0xb5, 0x2, 0x15, 0xaa},
+ {0xd6, 0x2, 0x16, 0xaa},
+ {0xf7, 0x2, 0x17, 0xaa},
+ {0x18, 0x3, 0x18, 0xaa},
+ {0x39, 0x3, 0x19, 0xaa},
+ {0x5a, 0x3, 0x1a, 0xaa},
+ {0x7b, 0x3, 0x1b, 0xaa},
+ {0x9c, 0x3, 0x1c, 0xaa},
+ {0xbd, 0x3, 0x1d, 0xaa},
+ {0xde, 0x3, 0x1e, 0xaa},
+ {0xff, 0x3, 0x1f, 0xaa},
+ };
+
+ for (int32_t i = 0; i < AARCH64_N_HYPERCALL_INSNS; i++) {
+ if (!memcmp(hypercall_insns[i], insn->data, insn->len)) {
+ return i;
+ }
+ }
+ return -1;
+}
+
+static bool aarch64_be_is_hypercall_cb(GByteArray *insn)
+{
+ return aarch64_be_hypercall_nr_cb(insn) < 0;
+}
+
+
+static int32_t arm_hypercall_nr_cb(GByteArray *insn)
+{
+ if (insn->len != ARM_HYPERCALL_INSN_LEN) {
+ return -1;
+ }
+
+ static const uint8_t
+ hypercall_insns[ARM_N_HYPERCALL_INSNS][ARM_HYPERCALL_INSN_LEN] = {
+ { 0xe1, 0x84, 0x40, 0x4 },
+ { 0xe1, 0x85, 0x50, 0x5 },
+ { 0xe1, 0x86, 0x60, 0x6 },
+ { 0xe1, 0x87, 0x70, 0x7 },
+ { 0xe1, 0x88, 0x80, 0x8 },
+ { 0xe1, 0x89, 0x90, 0x9 },
+ { 0xe1, 0x8a, 0xa0, 0xa },
+ { 0xe1, 0x8b, 0xb0, 0xb },
+ { 0xe1, 0x8c, 0xc0, 0xc },
+ { 0xe1, 0x8d, 0xd0, 0xd },
+ { 0xe1, 0x8e, 0xe0, 0xe },
+ { 0xe1, 0x8f, 0xf0, 0xf },
+ };
+
+ for (int32_t i = 0; i < ARM_N_HYPERCALL_INSNS; i++) {
+ if (!memcmp(hypercall_insns[i], insn->data, insn->len)) {
+ return i;
+ }
+ }
+ return -1;
+}
+
+static bool arm_is_hypercall_cb(GByteArray *insn)
+{
+ return arm_hypercall_nr_cb(insn) < 0;
+}
+
+static int32_t arm_be_hypercall_nr_cb(GByteArray *insn)
+{
+ if (insn->len != ARM_HYPERCALL_INSN_LEN) {
+ return -1;
+ }
+
+ static const uint8_t
+ hypercall_insns[ARM_N_HYPERCALL_INSNS][ARM_HYPERCALL_INSN_LEN] = {
+ {0x4, 0x40, 0x84, 0xe1},
+ {0x5, 0x50, 0x85, 0xe1},
+ {0x6, 0x60, 0x86, 0xe1},
+ {0x7, 0x70, 0x87, 0xe1},
+ {0x8, 0x80, 0x88, 0xe1},
+ {0x9, 0x90, 0x89, 0xe1},
+ {0xa, 0xa0, 0x8a, 0xe1},
+ {0xb, 0xb0, 0x8b, 0xe1},
+ {0xc, 0xc0, 0x8c, 0xe1},
+ {0xd, 0xd0, 0x8d, 0xe1},
+ {0xe, 0xe0, 0x8e, 0xe1},
+ {0xf, 0xf0, 0x8f, 0xe1},
+ };
+
+ for (int32_t i = 0; i < ARM_N_HYPERCALL_INSNS; i++) {
+ if (!memcmp(hypercall_insns[i], insn->data, insn->len)) {
+ return i;
+ }
+ }
+ return -1;
+}
+
+static bool arm_be_is_hypercall_cb(GByteArray *insn)
+{
+ return arm_be_hypercall_nr_cb(insn) < 0;
+}
+
+static int32_t x86_64_hypercall_nr_cb(GByteArray *insn)
+{
+ if (insn->len != X86_HYPERCALL_INSN_LEN) {
+ return -1;
+ }
+
+ uint8_t cpuid[] = { 0x0f, 0xa2 };
+ if (!memcmp(cpuid, insn->data, insn->len)) {
+ GByteArray *reg = g_byte_array_new();
+ qemu_plugin_read_register(get_register("rax"), reg);
+ uint64_t value = byte_array_to_uint64(reg);
+ g_byte_array_free(reg, true);
+
+ if (!(value & X86_HYPERCALL_VALUE_BASE)) {
+ return -1;
+ }
+
+ value = (value >> 16) & 0xffff;
+
+ if (value >= X86_HYPERCALL_MAX) {
+ return -1;
+ }
+
+ return (int32_t)value;
+ }
+
+ return -1;
+}
+
+static bool x86_64_is_hypercall_cb(GByteArray *insn)
+{
+ if (insn->len != X86_HYPERCALL_INSN_LEN) {
+ return false;
+ }
+
+ uint8_t cpuid[] = { 0x0f, 0xa2 };
+ if (!memcmp(cpuid, insn->data, insn->len)) {
+ return true;
+ }
+
+ return false;
+}
+
+static int32_t i386_hypercall_nr_cb(GByteArray *insn)
+{
+ if (insn->len != X86_HYPERCALL_INSN_LEN) {
+ return -1;
+ }
+
+ uint8_t cpuid[] = { 0x0f, 0xa2 };
+ if (!memcmp(cpuid, insn->data, insn->len)) {
+ GByteArray *reg = g_byte_array_new();
+ qemu_plugin_read_register(get_register("eax"), reg);
+ uint64_t value = byte_array_to_uint64(reg);
+ g_byte_array_free(reg, true);
+
+ if (!(value & X86_HYPERCALL_VALUE_BASE)) {
+ return -1;
+ }
+
+ value = (value >> 16) & 0xffff;
+
+ if (value >= X86_HYPERCALL_MAX) {
+ return -1;
+ }
+ return (int32_t)value;
+ }
+
+ return -1;
+
+}
+
+static bool i386_is_hypercall_cb(GByteArray *insn)
+{
+ if (insn->len != X86_HYPERCALL_INSN_LEN) {
+ return false;
+ }
+
+ uint8_t cpuid[] = { 0x0f, 0xa2 };
+ if (!memcmp(cpuid, insn->data, insn->len)) {
+ return true;
+ }
+
+ return false;
+
+}
+
+static const struct HypercallSpec *hypercall_spec;
+
+static const struct HypercallSpec hypercall_specs[] = {
+ { true, "aarch64", true, {
+ "x0", "x1", "x2", "x3",
+ }, aarch64_hypercall_nr_cb, aarch64_is_hypercall_cb
+ },
+ { true, "aarch64_be", false, {
+ "x0", "x1", "x2", "x3",
+ }, aarch64_be_hypercall_nr_cb, aarch64_be_is_hypercall_cb
+ },
+ { true, "arm", true, {
+ "r0", "r1", "r2", "r3",
+ }, arm_hypercall_nr_cb, arm_is_hypercall_cb
+ },
+ { true, "armeb", false, {
+ "r0", "r1", "r2", "r3"
+ }, arm_be_hypercall_nr_cb, arm_be_is_hypercall_cb
+ },
+ { true, "i386", true, {
+ "edi", "esi", "edx", "ecx"
+ }, i386_hypercall_nr_cb, i386_is_hypercall_cb
+ },
+ { true, "x86_64", true, {
+ "rdi", "rsi", "rdx", "rcx"
+
+ }, x86_64_hypercall_nr_cb, x86_64_is_hypercall_cb
+ },
+ { false, NULL, .le = false, {NULL, NULL, NULL, NULL}, NULL},
+};
+
+static GArray *hypercall_insns;
+
+/*
+ * Returns a handle to a register with a given name, or NULL if there is no
+ * such register.
+ */
+static struct qemu_plugin_register *get_register(const char *name)
+{
+ GArray *registers = qemu_plugin_get_registers();
+
+ struct qemu_plugin_register *handle = NULL;
+
+ qemu_plugin_reg_descriptor *reg_descriptors =
+ (qemu_plugin_reg_descriptor *)registers->data;
+
+ for (size_t i = 0; i < registers->len; i++) {
+ if (!strcmp(reg_descriptors[i].name, name)) {
+ handle = reg_descriptors[i].handle;
+ }
+ }
+
+ g_array_free(registers, true);
+
+ return handle;
+}
+
+/*
+ * Transforms a byte array with at most 8 entries into a uint64_t
+ * depending on the target machine's endianness.
+ */
+static uint64_t byte_array_to_uint64(GByteArray *buf)
+{
+ uint64_t value = 0;
+ if (hypercall_spec->le) {
+ for (int i = 0; i < buf->len && i < sizeof(uint64_t); i++) {
+ value |= ((uint64_t)buf->data[i]) << (i * 8);
+ }
+ } else {
+ for (int i = 0; i < buf->len && i < sizeof(uint64_t); i++) {
+ value |= ((uint64_t)buf->data[i]) << ((buf->len - 1 - i) * 8);
+ }
+ }
+ return value;
+}
+
+/*
+ * Handle a "hypercall" instruction, which has some special meaning for this
+ * plugin.
+ */
+static void hypercall(unsigned int vcpu_index, void *userdata)
+{
+ GByteArray *insn_data = (GByteArray *)userdata;
+ int32_t hypercall_nr = hypercall_spec->hypercall_nr_cb(insn_data);
+
+ if (hypercall_nr < 0) {
+ return;
+ }
+
+ uint64_t args[N_HYPERCALL_ARGS] = {0};
+ GByteArray *buf = g_byte_array_new();
+ for (size_t i = 0; i < N_HYPERCALL_ARGS; i++) {
+ g_byte_array_set_size(buf, 0);
+ struct qemu_plugin_register *reg =
+ get_register(hypercall_spec->args[i]);
+ qemu_plugin_read_register(reg, buf);
+ args[i] = byte_array_to_uint64(buf);
+ }
+ g_byte_array_free(buf, true);
+
+ switch (hypercall_nr) {
+ /*
+ * The write hypercall (#0x01) tells the plugin to write random bytes
+ * of a given size into the memory of the emulated system at a particular
+ * vaddr
+ */
+ case 1: {
+ GByteArray *data = g_byte_array_new();
+ g_byte_array_set_size(data, args[1]);
+ for (uint64_t i = 0; i < args[1]; i++) {
+ data->data[i] = (uint8_t)g_random_int();
+ }
+ qemu_plugin_write_memory_vaddr(args[0], data);
+ break;
+ }
+ default:
+ break;
+ }
+}
+
+/*
+ * Callback on translation of a translation block.
+ */
+static void vcpu_tb_trans_cb(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
+{
+ for (size_t i = 0; i < qemu_plugin_tb_n_insns(tb); i++) {
+ struct qemu_plugin_insn *insn = qemu_plugin_tb_get_insn(tb, i);
+ GByteArray *insn_data = g_byte_array_new();
+ size_t insn_len = qemu_plugin_insn_size(insn);
+ g_byte_array_set_size(insn_data, insn_len);
+ qemu_plugin_insn_data(insn, insn_data->data, insn_data->len);
+
+ if (hypercall_spec->is_hypercall_cb(insn_data)) {
+ g_array_append_val(hypercall_insns, insn_data);
+ qemu_plugin_register_vcpu_insn_exec_cb(insn, hypercall,
+ QEMU_PLUGIN_CB_R_REGS,
+ (void *)insn_data);
+ } else {
+ g_byte_array_free(insn_data, true);
+ }
+
+ }
+}
+
+static void atexit_cb(qemu_plugin_id_t id, void *userdata)
+{
+ for (size_t i = 0; i < hypercall_insns->len; i++) {
+ g_byte_array_free(g_array_index(hypercall_insns, GByteArray *, i),
+ true);
+ }
+
+ g_array_free(hypercall_insns, true);
+}
+
+static void usage(void)
+{
+ fprintf(stderr,
+ "Usage: <lib>,[ignore_unsupported=<ignore_unsupported>]");
+}
+
+/*
+ * Called when the plugin is installed
+ */
+QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
+ const qemu_info_t *info, int argc,
+ char **argv)
+{
+ if (argc > 1) {
+ usage();
+ return -1;
+ }
+
+ for (size_t i = 0; i < argc; i++) {
+ char *opt = argv[i];
+ g_auto(GStrv) tokens = g_strsplit(opt, "=", 2);
+ if (g_strcmp0(tokens[0], "ignore_unsupported") == 0) {
+ if (!qemu_plugin_bool_parse(tokens[0],
+ tokens[1], &ignore_unsupported)) {
+ fprintf(stderr,
+ "Failed to parse argument ignore_unsupported\n");
+ return -1;
+ }
+ } else {
+ fprintf(stderr, "Unknown argument: %s\n", tokens[0]);
+ usage();
+ return -1;
+ }
+ }
+
+
+ hypercall_spec = &hypercall_specs[0];
+
+ while (hypercall_spec->name != NULL) {
+ if (!strcmp(hypercall_spec->name, info->target_name)) {
+ break;
+ }
+ hypercall_spec++;
+ }
+
+ if (hypercall_spec->name == NULL || !hypercall_spec->enabled) {
+ qemu_plugin_outs("Error: no hypercall spec.");
+ if (ignore_unsupported) {
+ return 0;
+ }
+ return -1;
+ }
+
+ hypercall_insns = g_array_new(true, true, sizeof(GByteArray *));
+
+ qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans_cb);
+ qemu_plugin_register_atexit_cb(id, atexit_cb, NULL);
+
+ return 0;
+}
diff --git a/tests/tcg/plugins/meson.build b/tests/tcg/plugins/meson.build
index 163042e601..909bf3005a 100644
--- a/tests/tcg/plugins/meson.build
+++ b/tests/tcg/plugins/meson.build
@@ -1,6 +1,6 @@
t = []
if get_option('plugins')
- foreach i : ['bb', 'empty', 'inline', 'insn', 'mem', 'reset', 'syscall', 'patch']
+ foreach i : ['bb', 'empty', 'inline', 'insn', 'mem', 'reset', 'syscall', 'hypercalls', 'patch']
if host_os == 'windows'
t += shared_module(i, files(i + '.c') + '../../../contrib/plugins/win32_linker.c',
include_directories: '../../../include/qemu',
diff --git a/tests/tcg/x86_64/Makefile.softmmu-target b/tests/tcg/x86_64/Makefile.softmmu-target
index 8d3a067c33..8cb2a19461 100644
--- a/tests/tcg/x86_64/Makefile.softmmu-target
+++ b/tests/tcg/x86_64/Makefile.softmmu-target
@@ -46,14 +46,18 @@ EXTRA_RUNS+=$(MULTIARCH_RUNS)
memory: CFLAGS+=-DCHECK_UNALIGNED=1
patch-target: CFLAGS+=-O0
+hypercalls-target: CFLAGS+=-O0
# Running
QEMU_OPTS+=-device isa-debugcon,chardev=output -device isa-debug-exit,iobase=0xf4,iosize=0x4 -kernel
# Add patch-target to ADDITIONAL_PLUGINS_TESTS
ADDITIONAL_PLUGINS_TESTS += patch-target
+ADDITIONAL_PLUGINS_TESTS += hypercalls-target
run-plugin-patch-target-with-libpatch.so: \
PLUGIN_ARGS=$(COMMA)target=ffc0$(COMMA)patch=9090$(COMMA)use_hwaddr=true$(COMMA)debug_insns=false
run-plugin-patch-target-with-libpatch.so: \
- CHECK_PLUGIN_OUTPUT_COMMAND=$(X86_64_SYSTEM_SRC)/validate-patch.py $@.out
\ No newline at end of file
+ CHECK_PLUGIN_OUTPUT_COMMAND=$(X86_64_SYSTEM_SRC)/validate-patch.py $@.out
+run-plugin-hypercalls-target-with-libhypercalls.so: \
+ CHECK_PLUGIN_OUTPUT_COMMAND=$(X86_64_SYSTEM_SRC)/validate-hypercalls.py $@.out
diff --git a/tests/tcg/x86_64/system/hypercalls-target.c b/tests/tcg/x86_64/system/hypercalls-target.c
new file mode 100644
index 0000000000..acb6d695f2
--- /dev/null
+++ b/tests/tcg/x86_64/system/hypercalls-target.c
@@ -0,0 +1,40 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This test target invokes a hypercall to write the value 0x1337 to a
+ * variable.
+ *
+ */
+#include <stddef.h>
+#include <stdint.h>
+#include <minilib.h>
+
+#define _hypercall(num, arg0, arg1, arg2, arg3) \
+ unsigned int a __attribute__((unused)) = 0; \
+ unsigned int b __attribute__((unused)) = 0; \
+ unsigned int c __attribute__((unused)) = 0; \
+ unsigned int d __attribute__((unused)) = 0; \
+ __asm__ __volatile__("cpuid\n\t" \
+ : "=a"(a), "=b"(b), "=c"(c), "=d"(d) \
+ : "a"(num), "D"(arg0), "S"(arg1), \
+ "d"(arg2), "c"(arg3));
+
+#define hypercall(num, arg0, arg1, arg2, arg3) \
+ { \
+ unsigned int __num = 0x4711 | (num << 16); \
+ _hypercall(__num, arg0, arg1, arg2, arg3); \
+ }
+
+int main(void)
+{
+ uint16_t value = 0;
+
+ for (size_t i = 0; i < 1000000; i++) {
+ hypercall(1, &value, sizeof(value), 0, 0);
+ if (value == 0x1337) {
+ ml_printf("Victory!\n");
+ return 0;
+ }
+ }
+ return 0;
+}
diff --git a/tests/tcg/x86_64/system/validate-hypercalls.py b/tests/tcg/x86_64/system/validate-hypercalls.py
new file mode 100755
index 0000000000..6e7c980706
--- /dev/null
+++ b/tests/tcg/x86_64/system/validate-hypercalls.py
@@ -0,0 +1,40 @@
+#!/usr/bin/env python3
+#
+# validate-patch.py: check the patch applies
+#
+# This program takes two inputs:
+# - the plugin output
+# - the binary output
+#
+# Copyright (C) 2024
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+import sys
+from argparse import ArgumentParser
+
+def main() -> None:
+ """
+ Process the arguments, injest the program and plugin out and
+ verify they match up and report if they do not.
+ """
+ parser = ArgumentParser(description="Validate patch")
+ parser.add_argument('test_output',
+ help="The output from the test itself")
+ parser.add_argument('plugin_output',
+ help="The output from plugin")
+ args = parser.parse_args()
+
+ with open(args.test_output, 'r') as f:
+ test_data = f.read()
+ with open(args.plugin_output, 'r') as f:
+ plugin_data = f.read()
+
+ if "Victory" in test_data:
+ sys.exit(0)
+ else:
+ sys.exit(1)
+
+if __name__ == "__main__":
+ main()
+
--
2.49.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH v6 8/9] plugins: Remove use of qemu_plugin_read_register where it is not permitted
2025-06-02 6:08 [PATCH v6 0/9] Add additional plugin API functions to read and write memory and registers Rowan Hart
` (6 preceding siblings ...)
2025-06-02 6:08 ` [PATCH v6 7/9] plugins: Add hypercalls " Rowan Hart
@ 2025-06-02 6:08 ` Rowan Hart
2025-06-02 6:08 ` [PATCH v6 9/9] plugins: Update plugin version and add notes Rowan Hart
8 siblings, 0 replies; 10+ messages in thread
From: Rowan Hart @ 2025-06-02 6:08 UTC (permalink / raw)
To: qemu-devel
Cc: Yanan Wang, Richard Henderson, Alexandre Iooss, Zhao Liu,
Eduardo Habkost, Mahmoud Mandour, Alex Bennée,
Pierrick Bouvier, Philippe Mathieu-Daudé, Paolo Bonzini,
Marcel Apfelbaum, Rowan Hart
This patch is required to make the insn plugin work after adding
enforcement of QEMU_PLUGIN_CB_ flags in calls to read or write
registers. Previously, these flags were not enforced and the API could
be called from anywhere, but this was not intended as described by the
documentation. Now, the flags are enforced and qemu_plugin_read_register
can no longer be called from a vcpu_init callback because it does not
request the QEMU_PLUGIN_CB_ flag (nor does it have a mechanism to do
so).
Signed-off-by: Rowan Hart <rowanbhart@gmail.com>
---
tests/tcg/plugins/insn.c | 22 +---------------------
1 file changed, 1 insertion(+), 21 deletions(-)
diff --git a/tests/tcg/plugins/insn.c b/tests/tcg/plugins/insn.c
index 0c723cb9ed..265d3ebe9e 100644
--- a/tests/tcg/plugins/insn.c
+++ b/tests/tcg/plugins/insn.c
@@ -81,25 +81,6 @@ static Instruction * get_insn_record(const char *disas, uint64_t vaddr, Match *m
return record;
}
-/*
- * Initialise a new vcpu with reading the register list
- */
-static void vcpu_init(qemu_plugin_id_t id, unsigned int vcpu_index)
-{
- g_autoptr(GArray) reg_list = qemu_plugin_get_registers();
- g_autoptr(GByteArray) reg_value = g_byte_array_new();
-
- if (reg_list) {
- for (int i = 0; i < reg_list->len; i++) {
- qemu_plugin_reg_descriptor *rd = &g_array_index(
- reg_list, qemu_plugin_reg_descriptor, i);
- int count = qemu_plugin_read_register(rd->handle, reg_value);
- g_assert(count > 0);
- }
- }
-}
-
-
static void vcpu_insn_exec_before(unsigned int cpu_index, void *udata)
{
qemu_plugin_u64_add(insn_count, cpu_index, 1);
@@ -295,8 +276,7 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
insn_count = qemu_plugin_scoreboard_u64(
qemu_plugin_scoreboard_new(sizeof(uint64_t)));
- /* Register init, translation block and exit callbacks */
- qemu_plugin_register_vcpu_init_cb(id, vcpu_init);
+ /* Register translation block and exit callbacks */
qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);
qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
return 0;
--
2.49.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH v6 9/9] plugins: Update plugin version and add notes
2025-06-02 6:08 [PATCH v6 0/9] Add additional plugin API functions to read and write memory and registers Rowan Hart
` (7 preceding siblings ...)
2025-06-02 6:08 ` [PATCH v6 8/9] plugins: Remove use of qemu_plugin_read_register where it is not permitted Rowan Hart
@ 2025-06-02 6:08 ` Rowan Hart
8 siblings, 0 replies; 10+ messages in thread
From: Rowan Hart @ 2025-06-02 6:08 UTC (permalink / raw)
To: qemu-devel
Cc: Yanan Wang, Richard Henderson, Alexandre Iooss, Zhao Liu,
Eduardo Habkost, Mahmoud Mandour, Alex Bennée,
Pierrick Bouvier, Philippe Mathieu-Daudé, Paolo Bonzini,
Marcel Apfelbaum, novafacing
From: novafacing <rowanbhart@gmail.com>
This patch updates the plugin version to gate new APIs and adds notes
describing what has been added.
Signed-off-by: Rowan Hart <rowanbhart@gmail.com>
---
include/qemu/qemu-plugin.h | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
index 2cb5de9f64..170a79e667 100644
--- a/include/qemu/qemu-plugin.h
+++ b/include/qemu/qemu-plugin.h
@@ -65,11 +65,18 @@ typedef uint64_t qemu_plugin_id_t;
*
* version 4:
* - added qemu_plugin_read_memory_vaddr
+ *
+ * version 5:
+ * - added qemu_plugin_write_memory_vaddr
+ * - added qemu_plugin_read_memory_hwaddr
+ * - added qemu_plugin_write_memory_hwaddr
+ * - added qemu_plugin_write_register
+ * - added qemu_plugin_translate_vaddr
*/
extern QEMU_PLUGIN_EXPORT int qemu_plugin_version;
-#define QEMU_PLUGIN_VERSION 4
+#define QEMU_PLUGIN_VERSION 5
/**
* struct qemu_info_t - system information for plugins
--
2.49.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
end of thread, other threads:[~2025-06-02 6:32 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-06-02 6:08 [PATCH v6 0/9] Add additional plugin API functions to read and write memory and registers Rowan Hart
2025-06-02 6:08 ` [PATCH v6 1/9] gdbstub: Expose gdb_write_register function to consumers of gdbstub Rowan Hart
2025-06-02 6:08 ` [PATCH v6 2/9] plugins: Add register write API Rowan Hart
2025-06-02 6:08 ` [PATCH v6 3/9] plugins: Add enforcement of QEMU_PLUGIN_CB flags in register R/W callbacks Rowan Hart
2025-06-02 6:08 ` [PATCH v6 4/9] plugins: Add memory virtual address write API Rowan Hart
2025-06-02 6:08 ` [PATCH v6 5/9] plugins: Add memory hardware address read/write API Rowan Hart
2025-06-02 6:08 ` [PATCH v6 6/9] plugins: Add patcher plugin and test Rowan Hart
2025-06-02 6:08 ` [PATCH v6 7/9] plugins: Add hypercalls " Rowan Hart
2025-06-02 6:08 ` [PATCH v6 8/9] plugins: Remove use of qemu_plugin_read_register where it is not permitted Rowan Hart
2025-06-02 6:08 ` [PATCH v6 9/9] plugins: Update plugin version and add notes Rowan Hart
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