Re: [Qemu-devel] [RFC PATCH 2/6] ram_blocks: Convert to a QLIST

[Cam Macdonell]

On Tue, Jun 8, 2010 at 1:15 PM, Alex Williamson
<address@hidden> wrote:
> This makes the RAM block list easier to manipulate.  Also incorporate
> relevant variables into the RAMList struct.
>
> Signed-off-by: Alex Williamson <address@hidden>
> ---
>
>  arch_init.c |   14 ++++++-----
>  cpu-all.h   |   28 ++++++++++++++++-------
>  exec.c      |   72 
> ++++++++++++++++++-----------------------------------------
>  3 files changed, 49 insertions(+), 65 deletions(-)
>
> diff --git a/arch_init.c b/arch_init.c
> index 8e849a8..43e42ba 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -110,7 +110,7 @@ static int ram_save_block(QEMUFile *f)
>     ram_addr_t addr = 0;
>     int bytes_sent = 0;
>
> -    while (addr < last_ram_offset) {
> +    while (addr < ram.last_offset) {
>         if (cpu_physical_memory_get_dirty(current_addr, 
> MIGRATION_DIRTY_FLAG)) {
>             uint8_t *p;
>
> @@ -133,7 +133,7 @@ static int ram_save_block(QEMUFile *f)
>             break;
>         }
>         addr += TARGET_PAGE_SIZE;
> -        current_addr = (saved_addr + addr) % last_ram_offset;
> +        current_addr = (saved_addr + addr) % ram.last_offset;
>     }
>
>     return bytes_sent;
> @@ -146,7 +146,7 @@ static ram_addr_t ram_save_remaining(void)
>     ram_addr_t addr;
>     ram_addr_t count = 0;
>
> -    for (addr = 0; addr < last_ram_offset; addr += TARGET_PAGE_SIZE) {
> +    for (addr = 0; addr < ram.last_offset; addr += TARGET_PAGE_SIZE) {
>         if (cpu_physical_memory_get_dirty(addr, MIGRATION_DIRTY_FLAG)) {
>             count++;
>         }
> @@ -167,7 +167,7 @@ uint64_t ram_bytes_transferred(void)
>
>  uint64_t ram_bytes_total(void)
>  {
> -    return last_ram_offset;
> +    return ram.last_offset;
>  }
>
>  int ram_save_live(Monitor *mon, QEMUFile *f, int stage, void *opaque)
> @@ -191,7 +191,7 @@ int ram_save_live(Monitor *mon, QEMUFile *f, int stage, 
> void *opaque)
>         bytes_transferred = 0;
>
>         /* Make sure all dirty bits are set */
> -        for (addr = 0; addr < last_ram_offset; addr += TARGET_PAGE_SIZE) {
> +        for (addr = 0; addr < ram.last_offset; addr += TARGET_PAGE_SIZE) {
>             if (!cpu_physical_memory_get_dirty(addr, MIGRATION_DIRTY_FLAG)) {
>                 cpu_physical_memory_set_dirty(addr);
>             }
> @@ -200,7 +200,7 @@ int ram_save_live(Monitor *mon, QEMUFile *f, int stage, 
> void *opaque)
>         /* Enable dirty memory tracking */
>         cpu_physical_memory_set_dirty_tracking(1);
>
> -        qemu_put_be64(f, last_ram_offset | RAM_SAVE_FLAG_MEM_SIZE);
> +        qemu_put_be64(f, ram.last_offset | RAM_SAVE_FLAG_MEM_SIZE);
>     }
>
>     bytes_transferred_last = bytes_transferred;
> @@ -259,7 +259,7 @@ int ram_load(QEMUFile *f, void *opaque, int version_id)
>         addr &= TARGET_PAGE_MASK;
>
>         if (flags & RAM_SAVE_FLAG_MEM_SIZE) {
> -            if (addr != last_ram_offset) {
> +            if (addr != ram.last_offset) {
>                 return -EINVAL;
>             }
>         }
> diff --git a/cpu-all.h b/cpu-all.h
> index 77eaf85..458cb4b 100644
> --- a/cpu-all.h
> +++ b/cpu-all.h
> @@ -859,9 +859,21 @@ target_phys_addr_t cpu_get_phys_page_debug(CPUState 
> *env, target_ulong addr);
>  /* 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;
> +
> +typedef struct RAMBlock {
> +    uint8_t *host;
> +    ram_addr_t offset;
> +    ram_addr_t length;
> +    QLIST_ENTRY(RAMBlock) next;
> +} RAMBlock;

For my shared memory device I need a way to mark device memory as not
to be migrated.  Can a flag to be added to this struct to accomplish
this?

> +
> +typedef struct RAMList {
> +    uint8_t *phys_dirty;
> +    ram_addr_t last_offset;
> +    QLIST_HEAD(ram, RAMBlock) blocks;
> +} RAMList;
> +extern RAMList ram;
>
>  extern const char *mem_path;
>  extern int mem_prealloc;
> @@ -891,29 +903,29 @@ extern int mem_prealloc;
>  /* 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;
> +    return ram.phys_dirty[addr >> TARGET_PAGE_BITS] == 0xff;
>  }
>
>  static inline int cpu_physical_memory_get_dirty_flags(ram_addr_t addr)
>  {
> -    return phys_ram_dirty[addr >> TARGET_PAGE_BITS];
> +    return ram.phys_dirty[addr >> TARGET_PAGE_BITS];
>  }
>
>  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 ram.phys_dirty[addr >> TARGET_PAGE_BITS] & dirty_flags;
>  }
>
>  static inline void cpu_physical_memory_set_dirty(ram_addr_t addr)
>  {
> -    phys_ram_dirty[addr >> TARGET_PAGE_BITS] = 0xff;
> +    ram.phys_dirty[addr >> TARGET_PAGE_BITS] = 0xff;
>  }
>
>  static inline int cpu_physical_memory_set_dirty_flags(ram_addr_t addr,
>                                                       int dirty_flags)
>  {
> -    return phys_ram_dirty[addr >> TARGET_PAGE_BITS] |= dirty_flags;
> +    return ram.phys_dirty[addr >> TARGET_PAGE_BITS] |= dirty_flags;
>  }
>
>  static inline void cpu_physical_memory_mask_dirty_range(ram_addr_t start,
> @@ -925,7 +937,7 @@ static inline void 
> cpu_physical_memory_mask_dirty_range(ram_addr_t start,
>
>     len = length >> TARGET_PAGE_BITS;
>     mask = ~dirty_flags;
> -    p = phys_ram_dirty + (start >> TARGET_PAGE_BITS);
> +    p = ram.phys_dirty + (start >> TARGET_PAGE_BITS);
>     for (i = 0; i < len; i++) {
>         p[i] &= mask;
>     }
> diff --git a/exec.c b/exec.c
> index c60f9e7..d785de3 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -116,21 +116,9 @@ uint8_t *code_gen_ptr;
>
>  #if !defined(CONFIG_USER_ONLY)
>  int phys_ram_fd;
> -uint8_t *phys_ram_dirty;
>  static int in_migration;
>
> -typedef struct RAMBlock {
> -    uint8_t *host;
> -    ram_addr_t offset;
> -    ram_addr_t length;
> -    struct RAMBlock *next;
> -} RAMBlock;
> -
> -static RAMBlock *ram_blocks;
> -/* TODO: When we implement (and use) ram deallocation (e.g. for hotplug)
> -   then we can no longer assume contiguous ram offsets, and external uses
> -   of this variable will break.  */
> -ram_addr_t last_ram_offset;
> +RAMList ram = { .blocks = QLIST_HEAD_INITIALIZER(ram) };
>  #endif
>
>  CPUState *first_cpu;
> @@ -2795,18 +2783,17 @@ ram_addr_t qemu_ram_map(ram_addr_t size, void *host)
>
>     new_block->host = host;
>
> -    new_block->offset = last_ram_offset;
> +    new_block->offset = ram.last_offset;
>     new_block->length = size;
>
> -    new_block->next = ram_blocks;
> -    ram_blocks = new_block;
> +    QLIST_INSERT_HEAD(&ram.blocks, new_block, next);
>
> -    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),
> +    ram.phys_dirty = qemu_realloc(ram.phys_dirty,
> +        (ram.last_offset + size) >> TARGET_PAGE_BITS);
> +    memset(ram.phys_dirty + (ram.last_offset >> TARGET_PAGE_BITS),
>            0xff, size >> TARGET_PAGE_BITS);
>
> -    last_ram_offset += size;
> +    ram.last_offset += size;
>
>     if (kvm_enabled())
>         kvm_setup_guest_memory(new_block->host, size);
> @@ -2864,31 +2851,17 @@ void qemu_ram_free(ram_addr_t addr)
>  */
>  void *qemu_get_ram_ptr(ram_addr_t addr)
>  {
> -    RAMBlock *prev;
> -    RAMBlock **prevp;
>     RAMBlock *block;
>
> -    prev = NULL;
> -    prevp = &ram_blocks;
> -    block = ram_blocks;
> -    while (block && (block->offset > addr
> -                     || block->offset + block->length <= addr)) {
> -        if (prev)
> -          prevp = &prev->next;
> -        prev = block;
> -        block = block->next;
> -    }
> -    if (!block) {
> -        fprintf(stderr, "Bad ram offset %" PRIx64 "\n", (uint64_t)addr);
> -        abort();
> -    }
> -    /* Move this entry to to start of the list.  */
> -    if (prev) {
> -        prev->next = block->next;
> -        block->next = *prevp;
> -        *prevp = block;
> +    QLIST_FOREACH(block, &ram.blocks, next) {
> +        if (addr - block->offset < block->length) {
> +            QLIST_REMOVE(block, next);
> +            QLIST_INSERT_HEAD(&ram.blocks, block, next);
> +            return block->host + (addr - block->offset);
> +        }
>     }
> -    return block->host + (addr - block->offset);
> +
> +    return NULL;
>  }
>
>  int do_qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr)
> @@ -2896,15 +2869,14 @@ int do_qemu_ram_addr_from_host(void *ptr, ram_addr_t 
> *ram_addr)
>     RAMBlock *block;
>     uint8_t *host = ptr;
>
> -    block = ram_blocks;
> -    while (block && (block->host > host
> -                     || block->host + block->length <= host)) {
> -        block = block->next;
> +    QLIST_FOREACH(block, &ram.blocks, next) {
> +        if (host - block->host < block->length) {
> +            *ram_addr = block->offset + (host - block->host);
> +            return 0;
> +        }
>     }
> -    if (!block)
> -        return -1;
> -    *ram_addr = block->offset + (host - block->host);
> -    return 0;
> +
> +    return -1;
>  }
>
>  /* Some of the softmmu routines need to translate from a host pointer
>
>