Re: [RFC PATCH 01/20] Modify DIRTY_FLAG value and introduce DIRTY_IDX to use as indexes of bit-based phys_ram_dirty.

[Yoshiaki Tamura <tamura.yoshiaki@lab.ntt.co.jp>]

Anthony Liguori wrote:
> Hi,
>
> On 04/21/2010 12:57 AM, Yoshiaki Tamura wrote:
>> Replaces byte-based phys_ram_dirty bitmap with four (MASTER, VGA,
>> CODE, MIGRATION) bit-based phys_ram_dirty bitmap. On allocation, it
>> sets all bits in the bitmap. It uses ffs() to convert DIRTY_FLAG to
>> DIRTY_IDX.
>>
>> Modifies wrapper functions for byte-based phys_ram_dirty bitmap to
>> bit-based phys_ram_dirty bitmap. MASTER works as a buffer, and upon
>> get_diry() or get_dirty_flags(), it calls
>> cpu_physical_memory_sync_master() to update VGA and MIGRATION.
>
> Why use an additional bitmap for MASTER instead of just updating the
> VGA, CODE, and MIGRATION bitmaps together?

This way we don't have to think whether we should update VGA or MIGRATION. 
IIRC, we had this discussion on upstream before with Avi?

http://www.mail-archive.com/kvm@vger.kernel.org/msg30728.html

BTW, I also have the following TODO list regarding dirty bitmap.

1. Allocate vga and migration dirty bitmap dynamically.
2. Separate CODE and the other dirty bitmaps functions.

>
> Regards,
>
> Anthony Liguori
>
>> Replaces direct phys_ram_dirty access with wrapper functions to
>> prevent direct access to the phys_ram_dirty bitmap.
>>
>> Signed-off-by: Yoshiaki Tamura<tamura.yoshiaki@lab.ntt.co.jp>
>> Signed-off-by: OHMURA Kei<ohmura.kei@lab.ntt.co.jp>
>> ---
>> cpu-all.h | 130
>> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
>> exec.c | 60 ++++++++++++++--------------
>> 2 files changed, 152 insertions(+), 38 deletions(-)
>>
>> diff --git a/cpu-all.h b/cpu-all.h
>> index 51effc0..3f8762d 100644
>> --- a/cpu-all.h
>> +++ b/cpu-all.h
>> @@ -37,6 +37,9 @@
>>
>> #include "softfloat.h"
>>
>> +/* to use ffs in flag_to_idx() */
>> +#include<strings.h>
>> +
>> #if defined(HOST_WORDS_BIGENDIAN) != defined(TARGET_WORDS_BIGENDIAN)
>> #define BSWAP_NEEDED
>> #endif
>> @@ -846,7 +849,6 @@ int cpu_str_to_log_mask(const char *str);
>> /* memory API */
>>
>> extern int phys_ram_fd;
>> -extern uint8_t *phys_ram_dirty;
>> extern ram_addr_t ram_size;
>> extern ram_addr_t last_ram_offset;
>> extern uint8_t *bios_mem;
>> @@ -869,28 +871,140 @@ extern uint8_t *bios_mem;
>> /* Set if TLB entry is an IO callback. */
>> #define TLB_MMIO (1<< 5)
>>
>> +/* Use DIRTY_IDX as indexes of bit-based phys_ram_dirty. */
>> +#define MASTER_DIRTY_IDX 0
>> +#define VGA_DIRTY_IDX 1
>> +#define CODE_DIRTY_IDX 2
>> +#define MIGRATION_DIRTY_IDX 3
>> +#define NUM_DIRTY_IDX 4
>> +
>> +#define MASTER_DIRTY_FLAG (1<< MASTER_DIRTY_IDX)
>> +#define VGA_DIRTY_FLAG (1<< VGA_DIRTY_IDX)
>> +#define CODE_DIRTY_FLAG (1<< CODE_DIRTY_IDX)
>> +#define MIGRATION_DIRTY_FLAG (1<< MIGRATION_DIRTY_IDX)
>> +
>> +extern unsigned long *phys_ram_dirty[NUM_DIRTY_IDX];
>> +
>> +static inline int dirty_flag_to_idx(int flag)
>> +{
>> + return ffs(flag) - 1;
>> +}
>> +
>> +static inline int dirty_idx_to_flag(int idx)
>> +{
>> + return 1<< idx;
>> +}
>> +
>> int cpu_memory_rw_debug(CPUState *env, target_ulong addr,
>> uint8_t *buf, int len, int is_write);
>>
>> -#define VGA_DIRTY_FLAG 0x01
>> -#define CODE_DIRTY_FLAG 0x02
>> -#define MIGRATION_DIRTY_FLAG 0x08
>> -
>> /* read dirty bit (return 0 or 1) */
>> static inline int cpu_physical_memory_is_dirty(ram_addr_t addr)
>> {
>> - return phys_ram_dirty[addr>> TARGET_PAGE_BITS] == 0xff;
>> + unsigned long mask;
>> + ram_addr_t index = (addr>> TARGET_PAGE_BITS) / HOST_LONG_BITS;
>> + int offset = (addr>> TARGET_PAGE_BITS)& (HOST_LONG_BITS - 1);
>> +
>> + mask = 1UL<< offset;
>> + return (phys_ram_dirty[MASTER_DIRTY_IDX][index]& mask) == mask;
>> +}
>> +
>> +static inline void cpu_physical_memory_sync_master(ram_addr_t index)
>> +{
>> + if (phys_ram_dirty[MASTER_DIRTY_IDX][index]) {
>> + phys_ram_dirty[VGA_DIRTY_IDX][index]
>> + |= phys_ram_dirty[MASTER_DIRTY_IDX][index];
>> + phys_ram_dirty[MIGRATION_DIRTY_IDX][index]
>> + |= phys_ram_dirty[MASTER_DIRTY_IDX][index];
>> + phys_ram_dirty[MASTER_DIRTY_IDX][index] = 0UL;
>> + }
>> +}
>> +
>> +static inline int cpu_physical_memory_get_dirty_flags(ram_addr_t addr)
>> +{
>> + unsigned long mask;
>> + ram_addr_t index = (addr>> TARGET_PAGE_BITS) / HOST_LONG_BITS;
>> + int offset = (addr>> TARGET_PAGE_BITS)& (HOST_LONG_BITS - 1);
>> + int ret = 0, i;
>> +
>> + mask = 1UL<< offset;
>> + cpu_physical_memory_sync_master(index);
>> +
>> + for (i = VGA_DIRTY_IDX; i<= MIGRATION_DIRTY_IDX; i++) {
>> + if (phys_ram_dirty[i][index]& mask) {
>> + ret |= dirty_idx_to_flag(i);
>> + }
>> + }
>> +
>> + return ret;
>> +}
>> +
>> +static inline int cpu_physical_memory_get_dirty_idx(ram_addr_t addr,
>> + int dirty_idx)
>> +{
>> + unsigned long mask;
>> + ram_addr_t index = (addr>> TARGET_PAGE_BITS) / HOST_LONG_BITS;
>> + int offset = (addr>> TARGET_PAGE_BITS)& (HOST_LONG_BITS - 1);
>> +
>> + mask = 1UL<< offset;
>> + cpu_physical_memory_sync_master(index);
>> + return (phys_ram_dirty[dirty_idx][index]& mask) == mask;
>> }
>>
>> static inline int cpu_physical_memory_get_dirty(ram_addr_t addr,
>> int dirty_flags)
>> {
>> - return phys_ram_dirty[addr>> TARGET_PAGE_BITS]& dirty_flags;
>> + return cpu_physical_memory_get_dirty_idx(addr,
>> + dirty_flag_to_idx(dirty_flags));
>> }
>>
>> static inline void cpu_physical_memory_set_dirty(ram_addr_t addr)
>> {
>> - phys_ram_dirty[addr>> TARGET_PAGE_BITS] = 0xff;
>> + unsigned long mask;
>> + ram_addr_t index = (addr>> TARGET_PAGE_BITS) / HOST_LONG_BITS;
>> + int offset = (addr>> TARGET_PAGE_BITS)& (HOST_LONG_BITS - 1);
>> +
>> + mask = 1UL<< offset;
>> + phys_ram_dirty[MASTER_DIRTY_IDX][index] |= mask;
>> +}
>> +
>> +static inline void cpu_physical_memory_set_dirty_range(ram_addr_t addr,
>> + unsigned long mask)
>> +{
>> + ram_addr_t index = (addr>> TARGET_PAGE_BITS) / HOST_LONG_BITS;
>> +
>> + phys_ram_dirty[MASTER_DIRTY_IDX][index] |= mask;
>> +}
>> +
>> +static inline void cpu_physical_memory_set_dirty_flags(ram_addr_t addr,
>> + int dirty_flags)
>> +{
>> + unsigned long mask;
>> + ram_addr_t index = (addr>> TARGET_PAGE_BITS) / HOST_LONG_BITS;
>> + int offset = (addr>> TARGET_PAGE_BITS)& (HOST_LONG_BITS - 1);
>> +
>> + mask = 1UL<< offset;
>> + phys_ram_dirty[MASTER_DIRTY_IDX][index] |= mask;
>> +
>> + if (dirty_flags& CODE_DIRTY_FLAG) {
>> + phys_ram_dirty[CODE_DIRTY_IDX][index] |= mask;
>> + }
>> +}
>> +
>> +static inline void cpu_physical_memory_mask_dirty_range(ram_addr_t
>> start,
>> + unsigned long length,
>> + int dirty_flags)
>> +{
>> + ram_addr_t addr = start, index;
>> + unsigned long mask;
>> + int offset, i;
>> +
>> + for (i = 0; i< length; i += TARGET_PAGE_SIZE) {
>> + index = ((addr + i)>> TARGET_PAGE_BITS) / HOST_LONG_BITS;
>> + offset = ((addr + i)>> TARGET_PAGE_BITS)& (HOST_LONG_BITS - 1);
>> + mask = ~(1UL<< offset);
>> + phys_ram_dirty[dirty_flag_to_idx(dirty_flags)][index]&= mask;
>> + }
>> }
>>
>> void cpu_physical_memory_reset_dirty(ram_addr_t start, ram_addr_t end,
>> diff --git a/exec.c b/exec.c
>> index b647512..bf8d703 100644
>> --- a/exec.c
>> +++ b/exec.c
>> @@ -119,7 +119,7 @@ uint8_t *code_gen_ptr;
>>
>> #if !defined(CONFIG_USER_ONLY)
>> int phys_ram_fd;
>> -uint8_t *phys_ram_dirty;
>> +unsigned long *phys_ram_dirty[NUM_DIRTY_IDX];
>> uint8_t *bios_mem;
>> static int in_migration;
>>
>> @@ -1947,7 +1947,7 @@ static void tlb_protect_code(ram_addr_t ram_addr)
>> static void tlb_unprotect_code_phys(CPUState *env, ram_addr_t ram_addr,
>> target_ulong vaddr)
>> {
>> - phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS] |= CODE_DIRTY_FLAG;
>> + cpu_physical_memory_set_dirty_flags(ram_addr, CODE_DIRTY_FLAG);
>> }
>>
>> static inline void tlb_reset_dirty_range(CPUTLBEntry *tlb_entry,
>> @@ -1968,8 +1968,7 @@ void cpu_physical_memory_reset_dirty(ram_addr_t
>> start, ram_addr_t end,
>> {
>> CPUState *env;
>> unsigned long length, start1;
>> - int i, mask, len;
>> - uint8_t *p;
>> + int i;
>>
>> start&= TARGET_PAGE_MASK;
>> end = TARGET_PAGE_ALIGN(end);
>> @@ -1977,11 +1976,7 @@ void cpu_physical_memory_reset_dirty(ram_addr_t
>> start, ram_addr_t end,
>> length = end - start;
>> if (length == 0)
>> return;
>> - len = length>> TARGET_PAGE_BITS;
>> - mask = ~dirty_flags;
>> - p = phys_ram_dirty + (start>> TARGET_PAGE_BITS);
>> - for(i = 0; i< len; i++)
>> - p[i]&= mask;
>> + cpu_physical_memory_mask_dirty_range(start, length, dirty_flags);
>>
>> /* we modify the TLB cache so that the dirty bit will be set again
>> when accessing the range */
>> @@ -2643,6 +2638,7 @@ extern const char *mem_path;
>> ram_addr_t qemu_ram_alloc(ram_addr_t size)
>> {
>> RAMBlock *new_block;
>> + int i;
>>
>> size = TARGET_PAGE_ALIGN(size);
>> new_block = qemu_malloc(sizeof(*new_block));
>> @@ -2667,10 +2663,14 @@ ram_addr_t qemu_ram_alloc(ram_addr_t size)
>> new_block->next = ram_blocks;
>> ram_blocks = new_block;
>>
>> - phys_ram_dirty = qemu_realloc(phys_ram_dirty,
>> - (last_ram_offset + size)>> TARGET_PAGE_BITS);
>> - memset(phys_ram_dirty + (last_ram_offset>> TARGET_PAGE_BITS),
>> - 0xff, size>> TARGET_PAGE_BITS);
>> + for (i = MASTER_DIRTY_IDX; i< NUM_DIRTY_IDX; i++) {
>> + phys_ram_dirty[i]
>> + = qemu_realloc(phys_ram_dirty[i],
>> + BITMAP_SIZE(last_ram_offset + size));
>> + memset((uint8_t *)phys_ram_dirty[i] + BITMAP_SIZE(last_ram_offset),
>> + 0xff, BITMAP_SIZE(last_ram_offset + size)
>> + - BITMAP_SIZE(last_ram_offset));
>> + }
>>
>> last_ram_offset += size;
>>
>> @@ -2833,16 +2833,16 @@ static void notdirty_mem_writeb(void *opaque,
>> target_phys_addr_t ram_addr,
>> uint32_t val)
>> {
>> int dirty_flags;
>> - dirty_flags = phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS];
>> + dirty_flags = cpu_physical_memory_get_dirty_flags(ram_addr);
>> if (!(dirty_flags& CODE_DIRTY_FLAG)) {
>> #if !defined(CONFIG_USER_ONLY)
>> tb_invalidate_phys_page_fast(ram_addr, 1);
>> - dirty_flags = phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS];
>> + dirty_flags = cpu_physical_memory_get_dirty_flags(ram_addr);
>> #endif
>> }
>> stb_p(qemu_get_ram_ptr(ram_addr), val);
>> dirty_flags |= (0xff& ~CODE_DIRTY_FLAG);
>> - phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS] = dirty_flags;
>> + cpu_physical_memory_set_dirty_flags(ram_addr, dirty_flags);
>> /* we remove the notdirty callback only if the code has been
>> flushed */
>> if (dirty_flags == 0xff)
>> @@ -2853,16 +2853,16 @@ static void notdirty_mem_writew(void *opaque,
>> target_phys_addr_t ram_addr,
>> uint32_t val)
>> {
>> int dirty_flags;
>> - dirty_flags = phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS];
>> + dirty_flags = cpu_physical_memory_get_dirty_flags(ram_addr);
>> if (!(dirty_flags& CODE_DIRTY_FLAG)) {
>> #if !defined(CONFIG_USER_ONLY)
>> tb_invalidate_phys_page_fast(ram_addr, 2);
>> - dirty_flags = phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS];
>> + dirty_flags = cpu_physical_memory_get_dirty_flags(ram_addr);
>> #endif
>> }
>> stw_p(qemu_get_ram_ptr(ram_addr), val);
>> dirty_flags |= (0xff& ~CODE_DIRTY_FLAG);
>> - phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS] = dirty_flags;
>> + cpu_physical_memory_set_dirty_flags(ram_addr, dirty_flags);
>> /* we remove the notdirty callback only if the code has been
>> flushed */
>> if (dirty_flags == 0xff)
>> @@ -2873,16 +2873,16 @@ static void notdirty_mem_writel(void *opaque,
>> target_phys_addr_t ram_addr,
>> uint32_t val)
>> {
>> int dirty_flags;
>> - dirty_flags = phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS];
>> + dirty_flags = cpu_physical_memory_get_dirty_flags(ram_addr);
>> if (!(dirty_flags& CODE_DIRTY_FLAG)) {
>> #if !defined(CONFIG_USER_ONLY)
>> tb_invalidate_phys_page_fast(ram_addr, 4);
>> - dirty_flags = phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS];
>> + dirty_flags = cpu_physical_memory_get_dirty_flags(ram_addr);
>> #endif
>> }
>> stl_p(qemu_get_ram_ptr(ram_addr), val);
>> dirty_flags |= (0xff& ~CODE_DIRTY_FLAG);
>> - phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS] = dirty_flags;
>> + cpu_physical_memory_set_dirty_flags(ram_addr, dirty_flags);
>> /* we remove the notdirty callback only if the code has been
>> flushed */
>> if (dirty_flags == 0xff)
>> @@ -3334,8 +3334,8 @@ void cpu_physical_memory_rw(target_phys_addr_t
>> addr, uint8_t *buf,
>> /* invalidate code */
>> tb_invalidate_phys_page_range(addr1, addr1 + l, 0);
>> /* set dirty bit */
>> - phys_ram_dirty[addr1>> TARGET_PAGE_BITS] |=
>> - (0xff& ~CODE_DIRTY_FLAG);
>> + cpu_physical_memory_set_dirty_flags(
>> + addr1, (0xff& ~CODE_DIRTY_FLAG));
>> }
>> /* qemu doesn't execute guest code directly, but kvm does
>> therefore flush instruction caches */
>> @@ -3548,8 +3548,8 @@ void cpu_physical_memory_unmap(void *buffer,
>> target_phys_addr_t len,
>> /* invalidate code */
>> tb_invalidate_phys_page_range(addr1, addr1 + l, 0);
>> /* set dirty bit */
>> - phys_ram_dirty[addr1>> TARGET_PAGE_BITS] |=
>> - (0xff& ~CODE_DIRTY_FLAG);
>> + cpu_physical_memory_set_dirty_flags(
>> + addr1, (0xff& ~CODE_DIRTY_FLAG));
>> }
>> addr1 += l;
>> access_len -= l;
>> @@ -3685,8 +3685,8 @@ void stl_phys_notdirty(target_phys_addr_t addr,
>> uint32_t val)
>> /* invalidate code */
>> tb_invalidate_phys_page_range(addr1, addr1 + 4, 0);
>> /* set dirty bit */
>> - phys_ram_dirty[addr1>> TARGET_PAGE_BITS] |=
>> - (0xff& ~CODE_DIRTY_FLAG);
>> + cpu_physical_memory_set_dirty_flags(
>> + addr1, (0xff& ~CODE_DIRTY_FLAG));
>> }
>> }
>> }
>> @@ -3754,8 +3754,8 @@ void stl_phys(target_phys_addr_t addr, uint32_t
>> val)
>> /* invalidate code */
>> tb_invalidate_phys_page_range(addr1, addr1 + 4, 0);
>> /* set dirty bit */
>> - phys_ram_dirty[addr1>> TARGET_PAGE_BITS] |=
>> - (0xff& ~CODE_DIRTY_FLAG);
>> + cpu_physical_memory_set_dirty_flags(addr1,
>> + (0xff& ~CODE_DIRTY_FLAG));
>> }
>> }
>> }
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