diff mbox series

[v2,1/3] memory: add readonly support to memory_region_init_ram_from_file()

Message ID 20200916095150.755714-2-stefanha@redhat.com
State Superseded
Headers show
Series nvdimm: read-only file support | expand

Commit Message

Stefan Hajnoczi Sept. 16, 2020, 9:51 a.m. UTC
There is currently no way to open(O_RDONLY) and mmap(PROT_READ) when
creating a memory region from a file. This functionality is needed since
the underlying host file may not allow writing.

Add a bool readonly argument to memory_region_init_ram_from_file() and
the APIs it calls.

Extend memory_region_init_ram_from_file() rather than introducing a
memory_region_init_rom_from_file() API so that callers can easily make a
choice between read/write and read-only at runtime without calling
different APIs.

No new RAMBlock flag is introduced for read-only because it's unclear
whether RAMBlocks need to know that they are read-only. Pass a bool
readonly argument instead.

Both of these design decisions can be changed in the future. It just
seemed like the simplest approach to me.

Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 include/exec/memory.h     |  2 ++
 include/exec/ram_addr.h   |  5 +++--
 include/qemu/mmap-alloc.h |  2 ++
 backends/hostmem-file.c   |  2 +-
 exec.c                    | 18 +++++++++++-------
 softmmu/memory.c          |  7 +++++--
 util/mmap-alloc.c         | 10 ++++++----
 util/oslib-posix.c        |  2 +-
 8 files changed, 31 insertions(+), 17 deletions(-)

Comments

Igor Mammedov Dec. 14, 2020, 11:01 a.m. UTC | #1
On Wed, 16 Sep 2020 10:51:48 +0100
Stefan Hajnoczi <stefanha@redhat.com> wrote:

> There is currently no way to open(O_RDONLY) and mmap(PROT_READ) when

> creating a memory region from a file. This functionality is needed since

> the underlying host file may not allow writing.

> 

> Add a bool readonly argument to memory_region_init_ram_from_file() and

> the APIs it calls.

> 

> Extend memory_region_init_ram_from_file() rather than introducing a

> memory_region_init_rom_from_file() API so that callers can easily make a

> choice between read/write and read-only at runtime without calling

> different APIs.

> 

> No new RAMBlock flag is introduced for read-only because it's unclear

> whether RAMBlocks need to know that they are read-only. Pass a bool

> readonly argument instead.

> 

> Both of these design decisions can be changed in the future. It just

> seemed like the simplest approach to me.

> 

> Acked-by: Michael S. Tsirkin <mst@redhat.com>

> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>


Reviewed-by: Igor Mammedov <imammedo@redhat.com>


> ---

>  include/exec/memory.h     |  2 ++

>  include/exec/ram_addr.h   |  5 +++--

>  include/qemu/mmap-alloc.h |  2 ++

>  backends/hostmem-file.c   |  2 +-

>  exec.c                    | 18 +++++++++++-------

>  softmmu/memory.c          |  7 +++++--

>  util/mmap-alloc.c         | 10 ++++++----

>  util/oslib-posix.c        |  2 +-

>  8 files changed, 31 insertions(+), 17 deletions(-)

> 

> diff --git a/include/exec/memory.h b/include/exec/memory.h

> index f1bb2a7df5..a81fa26165 100644

> --- a/include/exec/memory.h

> +++ b/include/exec/memory.h

> @@ -879,6 +879,7 @@ void memory_region_init_resizeable_ram(MemoryRegion *mr,

>   *             - RAM_PMEM: the memory is persistent memory

>   *             Other bits are ignored now.

>   * @path: the path in which to allocate the RAM.

> + * @readonly: true to open @path for reading, false for read/write.

>   * @errp: pointer to Error*, to store an error if it happens.

>   *

>   * Note that this function does not do anything to cause the data in the

> @@ -891,6 +892,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr,

>                                        uint64_t align,

>                                        uint32_t ram_flags,

>                                        const char *path,

> +                                      bool readonly,

>                                        Error **errp);

>  

>  /**

> diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h

> index 3ef729a23c..2a0360a0f2 100644

> --- a/include/exec/ram_addr.h

> +++ b/include/exec/ram_addr.h

> @@ -110,6 +110,7 @@ long qemu_maxrampagesize(void);

>   *              - RAM_PMEM: the backend @mem_path or @fd is persistent memory

>   *              Other bits are ignored.

>   *  @mem_path or @fd: specify the backing file or device

> + *  @readonly: true to open @path for reading, false for read/write.

>   *  @errp: pointer to Error*, to store an error if it happens

>   *

>   * Return:

> @@ -118,9 +119,9 @@ long qemu_maxrampagesize(void);

>   */

>  RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,

>                                     uint32_t ram_flags, const char *mem_path,

> -                                   Error **errp);

> +                                   bool readonly, Error **errp);

>  RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,

> -                                 uint32_t ram_flags, int fd,

> +                                 uint32_t ram_flags, int fd, bool readonly,

>                                   Error **errp);

>  

>  RAMBlock *qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,

> diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h

> index e786266b92..8b7a5c70f3 100644

> --- a/include/qemu/mmap-alloc.h

> +++ b/include/qemu/mmap-alloc.h

> @@ -14,6 +14,7 @@ size_t qemu_mempath_getpagesize(const char *mem_path);

>   *  @size: the number of bytes to be mmaped

>   *  @align: if not zero, specify the alignment of the starting mapping address;

>   *          otherwise, the alignment in use will be determined by QEMU.

> + *  @readonly: true for a read-only mapping, false for read/write.

>   *  @shared: map has RAM_SHARED flag.

>   *  @is_pmem: map has RAM_PMEM flag.

>   *

> @@ -24,6 +25,7 @@ size_t qemu_mempath_getpagesize(const char *mem_path);

>  void *qemu_ram_mmap(int fd,

>                      size_t size,

>                      size_t align,

> +                    bool readonly,

>                      bool shared,

>                      bool is_pmem);

>  

> diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c

> index a3b2e8209e..dffdf142e0 100644

> --- a/backends/hostmem-file.c

> +++ b/backends/hostmem-file.c

> @@ -58,7 +58,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)

>                                       backend->size, fb->align,

>                                       (backend->share ? RAM_SHARED : 0) |

>                                       (fb->is_pmem ? RAM_PMEM : 0),

> -                                     fb->mem_path, errp);

> +                                     fb->mem_path, false, errp);

>      g_free(name);

>  #endif

>  }

> diff --git a/exec.c b/exec.c

> index e34b602bdf..f1e82dad7a 100644

> --- a/exec.c

> +++ b/exec.c

> @@ -1770,6 +1770,7 @@ static int64_t get_file_align(int fd)

>  

>  static int file_ram_open(const char *path,

>                           const char *region_name,

> +                         bool readonly,

>                           bool *created,

>                           Error **errp)

>  {

> @@ -1780,7 +1781,7 @@ static int file_ram_open(const char *path,

>  

>      *created = false;

>      for (;;) {

> -        fd = open(path, O_RDWR);

> +        fd = open(path, readonly ? O_RDONLY : O_RDWR);

>          if (fd >= 0) {

>              /* @path names an existing file, use it */

>              break;

> @@ -1832,6 +1833,7 @@ static int file_ram_open(const char *path,

>  static void *file_ram_alloc(RAMBlock *block,

>                              ram_addr_t memory,

>                              int fd,

> +                            bool readonly,

>                              bool truncate,

>                              Error **errp)

>  {

> @@ -1882,7 +1884,7 @@ static void *file_ram_alloc(RAMBlock *block,

>          perror("ftruncate");

>      }

>  

> -    area = qemu_ram_mmap(fd, memory, block->mr->align,

> +    area = qemu_ram_mmap(fd, memory, block->mr->align, readonly,

>                           block->flags & RAM_SHARED, block->flags & RAM_PMEM);

>      if (area == MAP_FAILED) {

>          error_setg_errno(errp, errno,

> @@ -2314,7 +2316,7 @@ 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,

> +                                 uint32_t ram_flags, int fd, bool readonly,

>                                   Error **errp)

>  {

>      RAMBlock *new_block;

> @@ -2368,7 +2370,8 @@ 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, readonly,

> +                                     !file_size, errp);

>      if (!new_block->host) {

>          g_free(new_block);

>          return NULL;

> @@ -2387,18 +2390,19 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,

>  

>  RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,

>                                     uint32_t ram_flags, const char *mem_path,

> -                                   Error **errp)

> +                                   bool readonly, Error **errp)

>  {

>      int fd;

>      bool created;

>      RAMBlock *block;

>  

> -    fd = file_ram_open(mem_path, memory_region_name(mr), &created, errp);

> +    fd = file_ram_open(mem_path, memory_region_name(mr), readonly, &created,

> +                       errp);

>      if (fd < 0) {

>          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, readonly, errp);

>      if (!block) {

>          if (created) {

>              unlink(mem_path);

> diff --git a/softmmu/memory.c b/softmmu/memory.c

> index d030eb6f7c..1b0d1d42c6 100644

> --- a/softmmu/memory.c

> +++ b/softmmu/memory.c

> @@ -1553,15 +1553,18 @@ void memory_region_init_ram_from_file(MemoryRegion *mr,

>                                        uint64_t align,

>                                        uint32_t ram_flags,

>                                        const char *path,

> +                                      bool readonly,

>                                        Error **errp)

>  {

>      Error *err = NULL;

>      memory_region_init(mr, owner, name, size);

>      mr->ram = true;

> +    mr->readonly = readonly;

>      mr->terminates = true;

>      mr->destructor = memory_region_destructor_ram;

>      mr->align = align;

> -    mr->ram_block = qemu_ram_alloc_from_file(size, mr, ram_flags, path, &err);

> +    mr->ram_block = qemu_ram_alloc_from_file(size, mr, ram_flags, path,

> +                                             readonly, &err);

>      mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0;

>      if (err) {

>          mr->size = int128_zero();

> @@ -1585,7 +1588,7 @@ 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, false, &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 27dcccd8ec..890fda6a35 100644

> --- a/util/mmap-alloc.c

> +++ b/util/mmap-alloc.c

> @@ -85,9 +85,11 @@ size_t qemu_mempath_getpagesize(const char *mem_path)

>  void *qemu_ram_mmap(int fd,

>                      size_t size,

>                      size_t align,

> +                    bool readonly,

>                      bool shared,

>                      bool is_pmem)

>  {

> +    int prot;

>      int flags;

>      int map_sync_flags = 0;

>      int guardfd;

> @@ -146,8 +148,9 @@ 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);

> +    prot = PROT_READ | (readonly ? 0 : PROT_WRITE);

> +

> +    ptr = mmap(guardptr + offset, size, prot, flags | map_sync_flags, fd, 0);

>  

>      if (ptr == MAP_FAILED && map_sync_flags) {

>          if (errno == ENOTSUP) {

> @@ -171,8 +174,7 @@ void *qemu_ram_mmap(int fd,

>           * if map failed with MAP_SHARED_VALIDATE | MAP_SYNC,

>           * we will remove these flags to handle compatibility.

>           */

> -        ptr = mmap(guardptr + offset, size, PROT_READ | PROT_WRITE,

> -                   flags, fd, 0);

> +        ptr = mmap(guardptr + offset, size, prot, flags, fd, 0);

>      }

>  

>      if (ptr == MAP_FAILED) {

> diff --git a/util/oslib-posix.c b/util/oslib-posix.c

> index ad8001a4ad..236b3a88c1 100644

> --- a/util/oslib-posix.c

> +++ b/util/oslib-posix.c

> @@ -227,7 +227,7 @@ 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, false, shared, false);

>  

>      if (ptr == MAP_FAILED) {

>          return NULL;
diff mbox series

Patch

diff --git a/include/exec/memory.h b/include/exec/memory.h
index f1bb2a7df5..a81fa26165 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -879,6 +879,7 @@  void memory_region_init_resizeable_ram(MemoryRegion *mr,
  *             - RAM_PMEM: the memory is persistent memory
  *             Other bits are ignored now.
  * @path: the path in which to allocate the RAM.
+ * @readonly: true to open @path for reading, false for read/write.
  * @errp: pointer to Error*, to store an error if it happens.
  *
  * Note that this function does not do anything to cause the data in the
@@ -891,6 +892,7 @@  void memory_region_init_ram_from_file(MemoryRegion *mr,
                                       uint64_t align,
                                       uint32_t ram_flags,
                                       const char *path,
+                                      bool readonly,
                                       Error **errp);
 
 /**
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index 3ef729a23c..2a0360a0f2 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -110,6 +110,7 @@  long qemu_maxrampagesize(void);
  *              - RAM_PMEM: the backend @mem_path or @fd is persistent memory
  *              Other bits are ignored.
  *  @mem_path or @fd: specify the backing file or device
+ *  @readonly: true to open @path for reading, false for read/write.
  *  @errp: pointer to Error*, to store an error if it happens
  *
  * Return:
@@ -118,9 +119,9 @@  long qemu_maxrampagesize(void);
  */
 RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
                                    uint32_t ram_flags, const char *mem_path,
-                                   Error **errp);
+                                   bool readonly, Error **errp);
 RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
-                                 uint32_t ram_flags, int fd,
+                                 uint32_t ram_flags, int fd, bool readonly,
                                  Error **errp);
 
 RAMBlock *qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h
index e786266b92..8b7a5c70f3 100644
--- a/include/qemu/mmap-alloc.h
+++ b/include/qemu/mmap-alloc.h
@@ -14,6 +14,7 @@  size_t qemu_mempath_getpagesize(const char *mem_path);
  *  @size: the number of bytes to be mmaped
  *  @align: if not zero, specify the alignment of the starting mapping address;
  *          otherwise, the alignment in use will be determined by QEMU.
+ *  @readonly: true for a read-only mapping, false for read/write.
  *  @shared: map has RAM_SHARED flag.
  *  @is_pmem: map has RAM_PMEM flag.
  *
@@ -24,6 +25,7 @@  size_t qemu_mempath_getpagesize(const char *mem_path);
 void *qemu_ram_mmap(int fd,
                     size_t size,
                     size_t align,
+                    bool readonly,
                     bool shared,
                     bool is_pmem);
 
diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c
index a3b2e8209e..dffdf142e0 100644
--- a/backends/hostmem-file.c
+++ b/backends/hostmem-file.c
@@ -58,7 +58,7 @@  file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
                                      backend->size, fb->align,
                                      (backend->share ? RAM_SHARED : 0) |
                                      (fb->is_pmem ? RAM_PMEM : 0),
-                                     fb->mem_path, errp);
+                                     fb->mem_path, false, errp);
     g_free(name);
 #endif
 }
diff --git a/exec.c b/exec.c
index e34b602bdf..f1e82dad7a 100644
--- a/exec.c
+++ b/exec.c
@@ -1770,6 +1770,7 @@  static int64_t get_file_align(int fd)
 
 static int file_ram_open(const char *path,
                          const char *region_name,
+                         bool readonly,
                          bool *created,
                          Error **errp)
 {
@@ -1780,7 +1781,7 @@  static int file_ram_open(const char *path,
 
     *created = false;
     for (;;) {
-        fd = open(path, O_RDWR);
+        fd = open(path, readonly ? O_RDONLY : O_RDWR);
         if (fd >= 0) {
             /* @path names an existing file, use it */
             break;
@@ -1832,6 +1833,7 @@  static int file_ram_open(const char *path,
 static void *file_ram_alloc(RAMBlock *block,
                             ram_addr_t memory,
                             int fd,
+                            bool readonly,
                             bool truncate,
                             Error **errp)
 {
@@ -1882,7 +1884,7 @@  static void *file_ram_alloc(RAMBlock *block,
         perror("ftruncate");
     }
 
-    area = qemu_ram_mmap(fd, memory, block->mr->align,
+    area = qemu_ram_mmap(fd, memory, block->mr->align, readonly,
                          block->flags & RAM_SHARED, block->flags & RAM_PMEM);
     if (area == MAP_FAILED) {
         error_setg_errno(errp, errno,
@@ -2314,7 +2316,7 @@  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,
+                                 uint32_t ram_flags, int fd, bool readonly,
                                  Error **errp)
 {
     RAMBlock *new_block;
@@ -2368,7 +2370,8 @@  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, readonly,
+                                     !file_size, errp);
     if (!new_block->host) {
         g_free(new_block);
         return NULL;
@@ -2387,18 +2390,19 @@  RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
 
 RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
                                    uint32_t ram_flags, const char *mem_path,
-                                   Error **errp)
+                                   bool readonly, Error **errp)
 {
     int fd;
     bool created;
     RAMBlock *block;
 
-    fd = file_ram_open(mem_path, memory_region_name(mr), &created, errp);
+    fd = file_ram_open(mem_path, memory_region_name(mr), readonly, &created,
+                       errp);
     if (fd < 0) {
         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, readonly, errp);
     if (!block) {
         if (created) {
             unlink(mem_path);
diff --git a/softmmu/memory.c b/softmmu/memory.c
index d030eb6f7c..1b0d1d42c6 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -1553,15 +1553,18 @@  void memory_region_init_ram_from_file(MemoryRegion *mr,
                                       uint64_t align,
                                       uint32_t ram_flags,
                                       const char *path,
+                                      bool readonly,
                                       Error **errp)
 {
     Error *err = NULL;
     memory_region_init(mr, owner, name, size);
     mr->ram = true;
+    mr->readonly = readonly;
     mr->terminates = true;
     mr->destructor = memory_region_destructor_ram;
     mr->align = align;
-    mr->ram_block = qemu_ram_alloc_from_file(size, mr, ram_flags, path, &err);
+    mr->ram_block = qemu_ram_alloc_from_file(size, mr, ram_flags, path,
+                                             readonly, &err);
     mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0;
     if (err) {
         mr->size = int128_zero();
@@ -1585,7 +1588,7 @@  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, false, &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 27dcccd8ec..890fda6a35 100644
--- a/util/mmap-alloc.c
+++ b/util/mmap-alloc.c
@@ -85,9 +85,11 @@  size_t qemu_mempath_getpagesize(const char *mem_path)
 void *qemu_ram_mmap(int fd,
                     size_t size,
                     size_t align,
+                    bool readonly,
                     bool shared,
                     bool is_pmem)
 {
+    int prot;
     int flags;
     int map_sync_flags = 0;
     int guardfd;
@@ -146,8 +148,9 @@  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);
+    prot = PROT_READ | (readonly ? 0 : PROT_WRITE);
+
+    ptr = mmap(guardptr + offset, size, prot, flags | map_sync_flags, fd, 0);
 
     if (ptr == MAP_FAILED && map_sync_flags) {
         if (errno == ENOTSUP) {
@@ -171,8 +174,7 @@  void *qemu_ram_mmap(int fd,
          * if map failed with MAP_SHARED_VALIDATE | MAP_SYNC,
          * we will remove these flags to handle compatibility.
          */
-        ptr = mmap(guardptr + offset, size, PROT_READ | PROT_WRITE,
-                   flags, fd, 0);
+        ptr = mmap(guardptr + offset, size, prot, flags, fd, 0);
     }
 
     if (ptr == MAP_FAILED) {
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index ad8001a4ad..236b3a88c1 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -227,7 +227,7 @@  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, false, shared, false);
 
     if (ptr == MAP_FAILED) {
         return NULL;