Re: [PATCH v5 01/50] multi-process: memory: alloc RAM from file at offset

[Jag Raman <jag.raman@oracle.com>]

On 3/3/2020 2:51 PM, Dr. David Alan Gilbert wrote:
> * Jagannathan Raman (jag.raman@oracle.com) wrote:
>> Allow RAM MemoryRegion to be created from an offset in a file, instead
>> of allocating at offset of 0 by default. This is needed to synchronize
>> RAM between QEMU & remote process.
>> This will be needed for the following patches.
>>
>> Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
>> Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
>> Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
> 
> This looks reasonable to me, so :
> 
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> 
> but can I suggest you take simple things like this and split them out
> into a separate little series;  I think people would probably take them
> even though the current users have a 0 offset.

Thanks Dave! We'll split these out of the series and integrate them
first.

--
Jag

> 
> Dave
> 
>> ---
>>   exec.c                    | 11 +++++++----
>>   include/exec/ram_addr.h   |  2 +-
>>   include/qemu/mmap-alloc.h |  3 ++-
>>   memory.c                  |  2 +-
>>   util/mmap-alloc.c         |  7 ++++---
>>   util/oslib-posix.c        |  2 +-
>>   6 files changed, 16 insertions(+), 11 deletions(-)
>>
>> diff --git a/exec.c b/exec.c
>> index c930040..e524185 100644
>> --- a/exec.c
>> +++ b/exec.c
>> @@ -1841,6 +1841,7 @@ static void *file_ram_alloc(RAMBlock *block,
>>                               ram_addr_t memory,
>>                               int fd,
>>                               bool truncate,
>> +                            off_t offset,
>>                               Error **errp)
>>   {
>>       Error *err = NULL;
>> @@ -1893,7 +1894,8 @@ static void *file_ram_alloc(RAMBlock *block,
>>       }
>>   
>>       area = qemu_ram_mmap(fd, memory, block->mr->align,
>> -                         block->flags & RAM_SHARED, block->flags & RAM_PMEM);
>> +                         block->flags & RAM_SHARED, block->flags & RAM_PMEM,
>> +                         offset);
>>       if (area == MAP_FAILED) {
>>           error_setg_errno(errp, errno,
>>                            "unable to map backing store for guest RAM");
>> @@ -2322,7 +2324,7 @@ static void ram_block_add(RAMBlock *new_block, Error **errp, bool shared)
>>   #ifdef CONFIG_POSIX
>>   RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
>>                                    uint32_t ram_flags, int fd,
>> -                                 Error **errp)
>> +                                 off_t offset, Error **errp)
>>   {
>>       RAMBlock *new_block;
>>       Error *local_err = NULL;
>> @@ -2367,7 +2369,8 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
>>       new_block->used_length = size;
>>       new_block->max_length = size;
>>       new_block->flags = ram_flags;
>> -    new_block->host = file_ram_alloc(new_block, size, fd, !file_size, errp);
>> +    new_block->host = file_ram_alloc(new_block, size, fd, !file_size, offset,
>> +                                     errp);
>>       if (!new_block->host) {
>>           g_free(new_block);
>>           return NULL;
>> @@ -2397,7 +2400,7 @@ RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
>>           return NULL;
>>       }
>>   
>> -    block = qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, errp);
>> +    block = qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, 0, errp);
>>       if (!block) {
>>           if (created) {
>>               unlink(mem_path);
>> diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
>> index 5e59a3d..1b9f489 100644
>> --- a/include/exec/ram_addr.h
>> +++ b/include/exec/ram_addr.h
>> @@ -121,7 +121,7 @@ RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
>>                                      Error **errp);
>>   RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
>>                                    uint32_t ram_flags, int fd,
>> -                                 Error **errp);
>> +                                 off_t offset, Error **errp);
>>   
>>   RAMBlock *qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
>>                                     MemoryRegion *mr, Error **errp);
>> diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h
>> index e786266..4f57985 100644
>> --- a/include/qemu/mmap-alloc.h
>> +++ b/include/qemu/mmap-alloc.h
>> @@ -25,7 +25,8 @@ void *qemu_ram_mmap(int fd,
>>                       size_t size,
>>                       size_t align,
>>                       bool shared,
>> -                    bool is_pmem);
>> +                    bool is_pmem,
>> +                    off_t start);
>>   
>>   void qemu_ram_munmap(int fd, void *ptr, size_t size);
>>   
>> diff --git a/memory.c b/memory.c
>> index aeaa8dc..131bc6c 100644
>> --- a/memory.c
>> +++ b/memory.c
>> @@ -1595,7 +1595,7 @@ void memory_region_init_ram_from_fd(MemoryRegion *mr,
>>       mr->destructor = memory_region_destructor_ram;
>>       mr->ram_block = qemu_ram_alloc_from_fd(size, mr,
>>                                              share ? RAM_SHARED : 0,
>> -                                           fd, &err);
>> +                                           fd, 0, &err);
>>       mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0;
>>       if (err) {
>>           mr->size = int128_zero();
>> diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c
>> index 27dcccd..a28f702 100644
>> --- a/util/mmap-alloc.c
>> +++ b/util/mmap-alloc.c
>> @@ -86,7 +86,8 @@ void *qemu_ram_mmap(int fd,
>>                       size_t size,
>>                       size_t align,
>>                       bool shared,
>> -                    bool is_pmem)
>> +                    bool is_pmem,
>> +                    off_t start)
>>   {
>>       int flags;
>>       int map_sync_flags = 0;
>> @@ -147,7 +148,7 @@ void *qemu_ram_mmap(int fd,
>>       offset = QEMU_ALIGN_UP((uintptr_t)guardptr, align) - (uintptr_t)guardptr;
>>   
>>       ptr = mmap(guardptr + offset, size, PROT_READ | PROT_WRITE,
>> -               flags | map_sync_flags, fd, 0);
>> +               flags | map_sync_flags, fd, start);
>>   
>>       if (ptr == MAP_FAILED && map_sync_flags) {
>>           if (errno == ENOTSUP) {
>> @@ -172,7 +173,7 @@ void *qemu_ram_mmap(int fd,
>>            * we will remove these flags to handle compatibility.
>>            */
>>           ptr = mmap(guardptr + offset, size, PROT_READ | PROT_WRITE,
>> -                   flags, fd, 0);
>> +                   flags, fd, start);
>>       }
>>   
>>       if (ptr == MAP_FAILED) {
>> diff --git a/util/oslib-posix.c b/util/oslib-posix.c
>> index 5a291cc..bd221dd 100644
>> --- a/util/oslib-posix.c
>> +++ b/util/oslib-posix.c
>> @@ -205,7 +205,7 @@ void *qemu_memalign(size_t alignment, size_t size)
>>   void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment, bool shared)
>>   {
>>       size_t align = QEMU_VMALLOC_ALIGN;
>> -    void *ptr = qemu_ram_mmap(-1, size, align, shared, false);
>> +    void *ptr = qemu_ram_mmap(-1, size, align, shared, false, 0);
>>   
>>       if (ptr == MAP_FAILED) {
>>           return NULL;
>> -- 
>> 1.8.3.1
>>
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> 
>