From 714efd540c95430a121183cf90c6fb1e96348bd5 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Wed, 1 Aug 2018 15:34:42 +0200 Subject: util/oslib-win32: indicate alignment for qemu_anon_ram_alloc() Let's set the alignment just like for the posix variant. This will implicitly set the alignment of the underlying memory region and therefore make memory_region_get_alignment(mr) return something > 0 for all memory backends applicable to PCDIMM/NVDIMM. The allocation granularity is ususally 64k, while the page size is 4k. The documentation of VirtualAlloc is not really comprehensible in case only MEM_COMMIT is specified without an address. We'll detect the actual values and then go for the bigger one. The expection is, that it will always be 64k aligned. (The assumption is that MEM_COMMIT does an implicit MEM_RESERVE, so the address will always be aligned to the allocation granularity. And the allocation granularity is always bigger than the page size). This will allow us to drop special handling in pc.c for memory_region_get_alignment(mr) == 0, as we can then assume that it is always set (and AFAICS >= getpagesize()). For pc in pc_memory_plug(), under Windows TARGET_PAGE_SIZE == getpagesize(), therefore alignment of DIMMs will not change, and therefore also not the guest physical memory layout. For spapr in spapr_memory_plug(), an alignment of 0 would have been used until now. As QEMU_ALIGN_UP will crash with the alignment being 0, this never worked, so we don't have to care about compatibility handling. Reviewed-by: David Gibson Signed-off-by: David Hildenbrand Message-Id: <20180801133444.11269-3-david@redhat.com> Reviewed-by: Igor Mammedov Signed-off-by: Paolo Bonzini --- util/oslib-win32.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) (limited to 'util') diff --git a/util/oslib-win32.c b/util/oslib-win32.c index bb5ad28bd3..25dd1595ad 100644 --- a/util/oslib-win32.c +++ b/util/oslib-win32.c @@ -67,15 +67,24 @@ void *qemu_memalign(size_t alignment, size_t size) return qemu_oom_check(qemu_try_memalign(alignment, size)); } +static int get_allocation_granularity(void) +{ + SYSTEM_INFO system_info; + + GetSystemInfo(&system_info); + return system_info.dwAllocationGranularity; +} + void *qemu_anon_ram_alloc(size_t size, uint64_t *align, bool shared) { void *ptr; - /* FIXME: this is not exactly optimal solution since VirtualAlloc - has 64Kb granularity, but at least it guarantees us that the - memory is page aligned. */ ptr = VirtualAlloc(NULL, size, MEM_COMMIT, PAGE_READWRITE); trace_qemu_anon_ram_alloc(size, ptr); + + if (ptr && align) { + *align = MAX(get_allocation_granularity(), getpagesize()); + } return ptr; } -- cgit v1.2.3