Hi,
I found out that this series missed QEMU 4.0 and I was going to
queue for 4.1, but unfortunately this patch conflicts with:
commit 2044c3e7116eeac0449dcb4a4130cc8f8b9310da
Author: Murilo Opsfelder Araujo <muri...@linux.ibm.com>
Date: Wed Jan 30 21:36:04 2019 -0200
mmap-alloc: unfold qemu_ram_mmap()
Unfold parts of qemu_ram_mmap() for the sake of understanding, moving
declarations to the top, and keeping architecture-specifics in the
ifdef-else blocks. No changes in the function behaviour.
Give ptr and ptr1 meaningful names:
ptr -> guardptr : pointer to the PROT_NONE guard region
ptr1 -> ptr : pointer to the mapped memory returned to caller
Signed-off-by: Murilo Opsfelder Araujo <muri...@linux.ibm.com>
Reviewed-by: Greg Kurz <gr...@kaod.org>
Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
I'm queueing patches 1-3 into machine-next[1], so only patches 4
and 5 need to be refreshed and resubmitted.
[1] https://github.com/ehabkost/qemu.git machine-next
On Fri, Feb 08, 2019 at 06:11:11PM +0800, Zhang, Yi wrote:
> From: Zhang Yi <yi.z.zh...@linux.intel.com>
>
> When a file supporting DAX is used as vNVDIMM backend, mmap it with
> MAP_SYNC flag in addition which can ensure file system metadata
> synced in each guest writes to the backend file, without other QEMU
> actions (e.g., periodic fsync() by QEMU).
>
> Current, We have below different possible use cases:
>
> 1. pmem=on is set, shared=on is set, MAP_SYNC supported:
> a: backend is a dax supporting file.
> - MAP_SYNC will active.
> b: backend is not a dax supporting file.
> - mmap will trigger a warning. then MAP_SYNC flag will be ignored
>
> 2. The rest of cases:
> - we will never pass the MAP_SYNC to mmap2
>
> Signed-off-by: Haozhong Zhang <haozhong.zh...@intel.com>
> Signed-off-by: Zhang Yi <yi.z.zh...@linux.intel.com>
> ---
> util/mmap-alloc.c | 45 ++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 44 insertions(+), 1 deletion(-)
>
> diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c
> index 97bbeed..2f21efd 100644
> --- a/util/mmap-alloc.c
> +++ b/util/mmap-alloc.c
> @@ -10,6 +10,13 @@
> * later. See the COPYING file in the top-level directory.
> */
>
> +#ifdef CONFIG_LINUX
> +#include <linux/mman.h>
> +#else /* !CONFIG_LINUX */
> +#define MAP_SYNC 0x0
> +#define MAP_SHARED_VALIDATE 0x0
> +#endif /* CONFIG_LINUX */
> +
> #include "qemu/osdep.h"
> #include "qemu/mmap-alloc.h"
> #include "qemu/host-utils.h"
> @@ -101,6 +108,8 @@ void *qemu_ram_mmap(int fd,
> #else
> void *ptr = mmap(0, total, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1,
> 0);
> #endif
> + int mmap_flags;
> + int map_sync_flags = 0;
> size_t offset;
> void *ptr1;
>
> @@ -111,13 +120,47 @@ void *qemu_ram_mmap(int fd,
> assert(is_power_of_2(align));
> /* Always align to host page size */
> assert(align >= getpagesize());
> + mmap_flags = shared ? MAP_SHARED : MAP_PRIVATE;
> + if (shared && is_pmem) {
> + map_sync_flags = MAP_SYNC | MAP_SHARED_VALIDATE;
> + mmap_flags |= map_sync_flags;
> + }
>
> offset = QEMU_ALIGN_UP((uintptr_t)ptr, align) - (uintptr_t)ptr;
> ptr1 = mmap(ptr + offset, size, PROT_READ | PROT_WRITE,
> MAP_FIXED |
> (fd == -1 ? MAP_ANONYMOUS : 0) |
> - (shared ? MAP_SHARED : MAP_PRIVATE),
> + mmap_flags,
> fd, 0);
> +
> +
> + if (ptr1 == MAP_FAILED && map_sync_flags) {
> + if (errno == ENOTSUP) {
> + char *proc_link, *file_name;
> + int len;
> + proc_link = g_strdup_printf("/proc/self/fd/%d", fd);
> + file_name = g_malloc0(PATH_MAX);
> + len = readlink(proc_link, file_name, PATH_MAX - 1);
> + if (len < 0) {
> + len = 0;
> + }
> + file_name[len] = '\0';
> + fprintf(stderr, "Warning: requesting persistence across crashes "
> + "for backend file %s failed. Proceeding without "
> + "persistence, data might become corrupted in case of
> host "
> + "crash.\n", file_name);
> + g_free(proc_link);
> + g_free(file_name);
> + }
> + /* if map failed with MAP_SHARED_VALIDATE | MAP_SYNC,
> + * we will remove these flags to handle compatibility.
> + */
> + ptr1 = mmap(ptr + offset, size, PROT_READ | PROT_WRITE,
> + MAP_FIXED |
> + (fd == -1 ? MAP_ANONYMOUS : 0) |
> + MAP_SHARED,
> + fd, 0);
> + }
> if (ptr1 == MAP_FAILED) {
> munmap(ptr, total);
> return MAP_FAILED;
> --
> 2.7.4
>
>
--
Eduardo
