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

[Anthony Liguori <aliguori@linux.vnet.ibm.com>]

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?

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));
>           }
>       }
>   }
>