Patchwork [RFC,2/6] ram_blocks: Convert to a QLIST

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Submitter Alex Williamson
Date June 8, 2010, 7:15 p.m.
Message ID <20100608191535.4451.48702.stgit@localhost.localdomain>
Download mbox | patch
Permalink /patch/55019/
State New
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Comments

Alex Williamson - June 8, 2010, 7:15 p.m.
This makes the RAM block list easier to manipulate.  Also incorporate
relevant variables into the RAMList struct.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

 arch_init.c |   14 ++++++-----
 cpu-all.h   |   28 ++++++++++++++++-------
 exec.c      |   72 ++++++++++++++++++-----------------------------------------
 3 files changed, 49 insertions(+), 65 deletions(-)
Chris Wright - June 8, 2010, 9:26 p.m.
* Alex Williamson (alex.williamson@redhat.com) wrote:
>  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;
> +
> +typedef struct RAMList {
> +    uint8_t *phys_dirty;
> +    ram_addr_t last_offset;
> +    QLIST_HEAD(ram, RAMBlock) blocks;
> +} RAMList;
> +extern RAMList ram;

such a generic name for global namespace

>  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;

Why not preserve the error message and abort()?  In error cases this
would now just segfault.

Minor nits aside, this too looks like a nice cleanup.

Acked-by: Chris Wright <chrisw@redhat.com>
Alex Williamson - June 8, 2010, 9:45 p.m.
On Tue, 2010-06-08 at 14:26 -0700, Chris Wright wrote:
> * Alex Williamson (alex.williamson@redhat.com) wrote:
> >  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;
> > +
> > +typedef struct RAMList {
> > +    uint8_t *phys_dirty;
> > +    ram_addr_t last_offset;
> > +    QLIST_HEAD(ram, RAMBlock) blocks;
> > +} RAMList;
> > +extern RAMList ram;
> 
> such a generic name for global namespace

Well it is _the_ ram, but yea... ;)  Suggestions?

> > -    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;
> 
> Why not preserve the error message and abort()?  In error cases this
> would now just segfault.

Guess I was hoping the caller might do something smart, but I'll put it
back since that hasn't happened.  Thanks,

Alex
Chris Wright - June 8, 2010, 9:51 p.m.
* Alex Williamson (alex.williamson@redhat.com) wrote:
> On Tue, 2010-06-08 at 14:26 -0700, Chris Wright wrote:
> > * Alex Williamson (alex.williamson@redhat.com) wrote:
> > >  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;
> > > +
> > > +typedef struct RAMList {
> > > +    uint8_t *phys_dirty;
> > > +    ram_addr_t last_offset;
> > > +    QLIST_HEAD(ram, RAMBlock) blocks;
> > > +} RAMList;
> > > +extern RAMList ram;
> > 
> > such a generic name for global namespace
> 
> Well it is _the_ ram, but yea... ;)  Suggestions?

_the_ram

/me ducks
Juan Quintela - June 9, 2010, 8:19 a.m.
Alex Williamson <alex.williamson@redhat.com> wrote:
> On Tue, 2010-06-08 at 14:26 -0700, Chris Wright wrote:
>> * Alex Williamson (alex.williamson@redhat.com) wrote:
>> >  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;
>> > +
>> > +typedef struct RAMList {
>> > +    uint8_t *phys_dirty;
>> > +    ram_addr_t last_offset;
>> > +    QLIST_HEAD(ram, RAMBlock) blocks;
>> > +} RAMList;
>> > +extern RAMList ram;
>> 
>> such a generic name for global namespace
>
> Well it is _the_ ram, but yea... ;)  Suggestions?

ram_block_list?

Later, Juan.
Cam Macdonell - June 9, 2010, 8:11 p.m.
On Tue, Jun 8, 2010 at 1:15 PM, Alex Williamson
<alex.williamson@redhat.com> wrote:
> This makes the RAM block list easier to manipulate.  Also incorporate
> relevant variables into the RAMList struct.
>
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> ---
>
>  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
>
>
Alex Williamson - June 9, 2010, 8:55 p.m.
On Wed, 2010-06-09 at 14:11 -0600, Cam Macdonell wrote:
> On Tue, Jun 8, 2010 at 1:15 PM, Alex Williamson
> > 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?

Yep, it should be easy to skip blocks during migration based on a flag
here.  I guess that probably means you'd also want a flag when you alloc
the block, so maybe it should be:

qemu_ram_alloc(DeviceState *dev, const char *name, ram_addr_t size, int flags)

Best to make that change now, then we can add it to the RAMBlock as we need.

Alex
Yoshiaki Tamura - June 9, 2010, 9:12 p.m.
2010/6/10 Alex Williamson <alex.williamson@redhat.com>:
> On Wed, 2010-06-09 at 14:11 -0600, Cam Macdonell wrote:
>> On Tue, Jun 8, 2010 at 1:15 PM, Alex Williamson
>> > 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?
>
> Yep, it should be easy to skip blocks during migration based on a flag
> here.  I guess that probably means you'd also want a flag when you alloc
> the block, so maybe it should be:
>
> qemu_ram_alloc(DeviceState *dev, const char *name, ram_addr_t size, int flags)
>
> Best to make that change now, then we can add it to the RAMBlock as we need.

I have a question that if a device doesn't want to be migrated, why is
it still connected during live migration? Shouldn't that be hot
unplugged before going into the live migration procedure?

Thanks,

Yoshi

>
> Alex
>
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
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>

Patch

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;
+
+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