From fdec9918578ec38738ecf250fa2c2656a44796b5 Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Fri, 15 Jun 2012 05:10:30 +0000 Subject: s390: autodetect map private By default qemu will use MAP_PRIVATE for guest pages. This will write protect pages and thus break on s390 systems that dont support this feature. Therefore qemu has a hack to always use MAP_SHARED for s390. But MAP_SHARED has other problems (no dirty pages tracking, a lot more swap overhead etc.) Newer systems allow the distinction via KVM_CAP_S390_COW. With this feature qemu can use the standard qemu alloc if available, otherwise it will use the old s390 hack. Signed-off-by: Christian Borntraeger Signed-off-by: Jens Freimann Acked-by: Jan Kiszka Signed-off-by: Alexander Graf --- exec.c | 18 +++--------------- 1 file changed, 3 insertions(+), 15 deletions(-) (limited to 'exec.c') diff --git a/exec.c b/exec.c index dd4833d..c9fa17d 100644 --- a/exec.c +++ b/exec.c @@ -2536,26 +2536,14 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host, exit(1); #endif } else { -#if defined(TARGET_S390X) && defined(CONFIG_KVM) - /* S390 KVM requires the topmost vma of the RAM to be smaller than - an system defined value, which is at least 256GB. Larger systems - have larger values. We put the guest between the end of data - segment (system break) and this value. We use 32GB as a base to - have enough room for the system break to grow. */ - new_block->host = mmap((void*)0x800000000, size, - PROT_EXEC|PROT_READ|PROT_WRITE, - MAP_SHARED | MAP_ANONYMOUS | MAP_FIXED, -1, 0); - if (new_block->host == MAP_FAILED) { - fprintf(stderr, "Allocating RAM failed\n"); - abort(); - } -#else if (xen_enabled()) { xen_ram_alloc(new_block->offset, size, mr); + } else if (kvm_enabled()) { + /* some s390/kvm configurations have special constraints */ + new_block->host = kvm_vmalloc(size); } else { new_block->host = qemu_vmalloc(size); } -#endif qemu_madvise(new_block->host, size, QEMU_MADV_MERGEABLE); } } -- cgit v1.1