Re: [Qemu-ppc] [PATCHv2 for-2.13 1/2] Make qemu_mempath_getpagesize() accept NULL

[Greg Kurz]

On Thu,  5 Apr 2018 12:20:01 +1000
David Gibson <address@hidden> wrote:

> qemu_mempath_getpagesize() gets the effective (host side) page size for
> a block of memory backed by an mmap()ed file on the host.  It requires
> the mem_path parameter to be non-NULL.
> 
> This ends up meaning all the callers need a different case for handling
> anonymous memory (for memory-backend-ram or default memory with -mem-path
> is not specified).
> 
> We can make all those callers a little simpler by

by "having" ?

> qemu_mempath_getpagesize() accept NULL, and treat that as the anonymous
> memory case.
> 
> Signed-off-by: David Gibson <address@hidden>
> ---

Reviewed-by: Greg Kurz <address@hidden>

>  exec.c            | 21 ++++++---------------
>  target/ppc/kvm.c  |  8 ++------
>  util/mmap-alloc.c | 26 ++++++++++++++------------
>  3 files changed, 22 insertions(+), 33 deletions(-)
> 
> diff --git a/exec.c b/exec.c
> index 02b1efebb7..b38b004563 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1488,19 +1488,14 @@ void ram_block_dump(Monitor *mon)
>   */
>  static int find_max_supported_pagesize(Object *obj, void *opaque)
>  {
> -    char *mem_path;
>      long *hpsize_min = opaque;
>  
>      if (object_dynamic_cast(obj, TYPE_MEMORY_BACKEND)) {
> -        mem_path = object_property_get_str(obj, "mem-path", NULL);
> -        if (mem_path) {
> -            long hpsize = qemu_mempath_getpagesize(mem_path);
> -            g_free(mem_path);
> -            if (hpsize < *hpsize_min) {
> -                *hpsize_min = hpsize;
> -            }
> -        } else {
> -            *hpsize_min = getpagesize();
> +        char *mem_path = object_property_get_str(obj, "mem-path", NULL);
> +        long hpsize = qemu_mempath_getpagesize(mem_path);
> +        g_free(mem_path);
> +        if (hpsize < *hpsize_min) {
> +            *hpsize_min = hpsize;
>          }
>      }
>  
> @@ -1513,11 +1508,7 @@ long qemu_getrampagesize(void)
>      long mainrampagesize;
>      Object *memdev_root;
>  
> -    if (mem_path) {
> -        mainrampagesize = qemu_mempath_getpagesize(mem_path);
> -    } else {
> -        mainrampagesize = getpagesize();
> -    }
> +    mainrampagesize = qemu_mempath_getpagesize(mem_path);
>  
>      /* it's possible we have memory-backend objects with
>       * hugepage-backed RAM. these may get mapped into system
> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> index 1bd38c6a90..f393eae127 100644
> --- a/target/ppc/kvm.c
> +++ b/target/ppc/kvm.c
> @@ -496,12 +496,8 @@ bool kvmppc_is_mem_backend_page_size_ok(const char 
> *obj_path)
>      char *mempath = object_property_get_str(mem_obj, "mem-path", NULL);
>      long pagesize;
>  
> -    if (mempath) {
> -        pagesize = qemu_mempath_getpagesize(mempath);
> -        g_free(mempath);
> -    } else {
> -        pagesize = getpagesize();
> -    }
> +    pagesize = qemu_mempath_getpagesize(mempath);
> +    g_free(mempath);
>  
>      return pagesize >= max_cpu_page_size;
>  }
> diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c
> index 2fd8cbcc6f..fd329eccd8 100644
> --- a/util/mmap-alloc.c
> +++ b/util/mmap-alloc.c
> @@ -50,19 +50,21 @@ size_t qemu_mempath_getpagesize(const char *mem_path)
>      struct statfs fs;
>      int ret;
>  
> -    do {
> -        ret = statfs(mem_path, &fs);
> -    } while (ret != 0 && errno == EINTR);
> -
> -    if (ret != 0) {
> -        fprintf(stderr, "Couldn't statfs() memory path: %s\n",
> -                strerror(errno));
> -        exit(1);
> -    }
> +    if (mem_path) {
> +        do {
> +            ret = statfs(mem_path, &fs);
> +        } while (ret != 0 && errno == EINTR);
>  
> -    if (fs.f_type == HUGETLBFS_MAGIC) {
> -        /* It's hugepage, return the huge page size */
> -        return fs.f_bsize;
> +        if (ret != 0) {
> +            fprintf(stderr, "Couldn't statfs() memory path: %s\n",
> +                    strerror(errno));
> +            exit(1);
> +        }
> +
> +        if (fs.f_type == HUGETLBFS_MAGIC) {
> +            /* It's hugepage, return the huge page size */
> +            return fs.f_bsize;
> +        }
>      }
>  #ifdef __sparc__
>      /* SPARC Linux needs greater alignment than the pagesize */