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* util/mmap-alloc: fix hugetlb support on ppc64Michael S. Tsirkin2015-12-021-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* exec: factor out duplicate mmap codeMichael S. Tsirkin2015-10-211-0/+10
Anonymous and file-backed RAM allocation are now almost exactly the same. Reduce code duplication by moving RAM mmap code out of oslib-posix.c and exec.c. Reported-by: Marc-André Lureau <mlureau@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Tested-by: Thibaut Collet <thibaut.collet@6wind.com>
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