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
qemu_mempath_getpagesize() accept NULL, and treat that as the anonymous
memory case.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 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 */
-- 
2.14.3

On Thu,  5 Apr 2018 12:20:01 +1000
David Gibson <david@gibson.dropbear.id.au> 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 <david@gibson.dropbear.id.au>
> ---

Reviewed-by: Greg Kurz <groug@kaod.org>

>  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 */

On Thu, Apr 05, 2018 at 03:56:36PM +0200, Greg Kurz wrote:
> On Thu,  5 Apr 2018 12:20:01 +1000
> David Gibson <david@gibson.dropbear.id.au> 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" ?

Yes, oops.

> > qemu_mempath_getpagesize() accept NULL, and treat that as the anonymous
> > memory case.
> > 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> 
> Reviewed-by: Greg Kurz <groug@kaod.org>
> 
> >  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 */
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson