diff options
| -rw-r--r-- | exec.c | 42 | ||||
| -rw-r--r-- | include/exec/cpu-all.h | 9 | ||||
| -rw-r--r-- | include/hw/boards.h | 7 | ||||
| -rw-r--r-- | include/qemu-common.h | 12 | ||||
| -rw-r--r-- | vl.c | 10 |
5 files changed, 80 insertions, 0 deletions
diff --git a/exec.c b/exec.c index 93128fd19a..963b91a018 100644 --- a/exec.c +++ b/exec.c @@ -93,6 +93,11 @@ static MemoryRegion io_mem_unassigned; #endif +#ifdef TARGET_PAGE_BITS_VARY +int target_page_bits; +bool target_page_bits_decided; +#endif + struct CPUTailQ cpus = QTAILQ_HEAD_INITIALIZER(cpus); /* current CPU in the current thread. It is only valid inside cpu_exec() */ @@ -102,8 +107,37 @@ __thread CPUState *current_cpu; 2 = Adaptive rate instruction counting. */ int use_icount; +bool set_preferred_target_page_bits(int bits) +{ + /* The target page size is the lowest common denominator for all + * the CPUs in the system, so we can only make it smaller, never + * larger. And we can't make it smaller once we've committed to + * a particular size. + */ +#ifdef TARGET_PAGE_BITS_VARY + assert(bits >= TARGET_PAGE_BITS_MIN); + if (target_page_bits == 0 || target_page_bits > bits) { + if (target_page_bits_decided) { + return false; + } + target_page_bits = bits; + } +#endif + return true; +} + #if !defined(CONFIG_USER_ONLY) +static void finalize_target_page_bits(void) +{ +#ifdef TARGET_PAGE_BITS_VARY + if (target_page_bits == 0) { + target_page_bits = TARGET_PAGE_BITS_MIN; + } + target_page_bits_decided = true; +#endif +} + typedef struct PhysPageEntry PhysPageEntry; struct PhysPageEntry { @@ -2807,6 +2841,14 @@ void cpu_register_map_client(QEMUBH *bh) void cpu_exec_init_all(void) { qemu_mutex_init(&ram_list.mutex); + /* The data structures we set up here depend on knowing the page size, + * so no more changes can be made after this point. + * In an ideal world, nothing we did before we had finished the + * machine setup would care about the target page size, and we could + * do this much later, rather than requiring board models to state + * up front what their requirements are. + */ + finalize_target_page_bits(); io_mem_init(); memory_map_init(); qemu_mutex_init(&map_client_list_lock); diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h index b6a705982f..861260d3db 100644 --- a/include/exec/cpu-all.h +++ b/include/exec/cpu-all.h @@ -189,6 +189,15 @@ void address_space_stq(AddressSpace *as, hwaddr addr, uint64_t val, /* page related stuff */ +#ifdef TARGET_PAGE_BITS_VARY +extern bool target_page_bits_decided; +extern int target_page_bits; +#define TARGET_PAGE_BITS ({ assert(target_page_bits_decided); \ + target_page_bits; }) +#else +#define TARGET_PAGE_BITS_MIN TARGET_PAGE_BITS +#endif + #define TARGET_PAGE_SIZE (1 << TARGET_PAGE_BITS) #define TARGET_PAGE_MASK ~(TARGET_PAGE_SIZE - 1) #define TARGET_PAGE_ALIGN(addr) (((addr) + TARGET_PAGE_SIZE - 1) & TARGET_PAGE_MASK) diff --git a/include/hw/boards.h b/include/hw/boards.h index e46a744bcd..a51da9c440 100644 --- a/include/hw/boards.h +++ b/include/hw/boards.h @@ -86,6 +86,12 @@ typedef struct { * Returns a @HotpluggableCPUList, which describes CPUs objects which * could be added with -device/device_add. * Caller is responsible for freeing returned list. + * @minimum_page_bits: + * If non-zero, the board promises never to create a CPU with a page size + * smaller than this, so QEMU can use a more efficient larger page + * size than the target architecture's minimum. (Attempting to create + * such a CPU will fail.) Note that changing this is a migration + * compatibility break for the machine. */ struct MachineClass { /*< private >*/ @@ -124,6 +130,7 @@ struct MachineClass { ram_addr_t default_ram_size; bool option_rom_has_mr; bool rom_file_has_mr; + int minimum_page_bits; HotplugHandler *(*get_hotplug_handler)(MachineState *machine, DeviceState *dev); diff --git a/include/qemu-common.h b/include/qemu-common.h index 9e8b0bd991..7e6e4feb4b 100644 --- a/include/qemu-common.h +++ b/include/qemu-common.h @@ -82,6 +82,18 @@ bool tcg_enabled(void); void cpu_exec_init_all(void); /** + * set_preferred_target_page_bits: + * @bits: number of bits needed to represent an address within the page + * + * Set the preferred target page size (the actual target page + * size may be smaller than any given CPU's preference). + * Returns true on success, false on failure (which can only happen + * if this is called after the system has already finalized its + * choice of page size and the requested page size is smaller than that). + */ +bool set_preferred_target_page_bits(int bits); + +/** * Sends a (part of) iovec down a socket, yielding when the socket is full, or * Receives data into a (part of) iovec from a socket, * yielding when there is no data in the socket. diff --git a/vl.c b/vl.c index 44e08b4fc0..4ec8120834 100644 --- a/vl.c +++ b/vl.c @@ -4088,6 +4088,16 @@ int main(int argc, char **argv, char **envp) } object_property_add_child(object_get_root(), "machine", OBJECT(current_machine), &error_abort); + + if (machine_class->minimum_page_bits) { + if (!set_preferred_target_page_bits(machine_class->minimum_page_bits)) { + /* This would be a board error: specifying a minimum smaller than + * a target's compile-time fixed setting. + */ + g_assert_not_reached(); + } + } + cpu_exec_init_all(); if (machine_class->hw_version) { |