diff options
| author | Michael S. Tsirkin <mst@redhat.com> | 2015-12-02 21:14:12 +0200 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2015-12-02 22:38:23 +0200 |
| commit | 7197fb4058bcb68986bae2bb2c04d6370f3e7218 (patch) | |
| tree | c61e664c27278f8497fb9fec90cbb88383bf1d0e /include | |
| parent | 0560b0e97df3da43651158c799c6d889f27529c3 (diff) | |
util/mmap-alloc: fix hugetlb support on ppc64
Since commit 8561c9244ddf1122d "exec: allocate PROT_NONE pages on top of
RAM", it is no longer possible to back guest RAM with hugepages on ppc64
hosts:
mmap(NULL, 285212672, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x3fff57000000
mmap(0x3fff57000000, 268435456, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED, 19, 0) = -1 EBUSY (Device or resource busy)
This is because on ppc64, Linux fixes a page size for a virtual address
at mmap time, so we can't switch a range of memory from anonymous
small pages to hugetlbs with MAP_FIXED.
See commit d0f13e3c20b6fb73ccb467bdca97fa7cf5a574cd
("[POWERPC] Introduce address space "slices"") in Linux
history for the details.
Detect this and create the PROT_NONE mapping using the same fd.
Naturally, this makes the guard page bigger with hugetlbfs.
Based on patch by Greg Kurz.
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Tested-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/qemu/mmap-alloc.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h index 56388e689b..0899b2f01e 100644 --- a/include/qemu/mmap-alloc.h +++ b/include/qemu/mmap-alloc.h @@ -3,6 +3,8 @@ #include "qemu-common.h" +size_t qemu_fd_getpagesize(int fd); + void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared); void qemu_ram_munmap(void *ptr, size_t size); |