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 <borntraeger@de.ibm.com>
Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Acked-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/kvm.h b/kvm.h
index 9c7b0ea6ae..ddc7c53cb0 100644
--- a/kvm.h
+++ b/kvm.h
@@ -70,6 +70,8 @@ int kvm_init_vcpu(CPUArchState *env);
 int kvm_cpu_exec(CPUArchState *env);
 
 #if !defined(CONFIG_USER_ONLY)
+void *kvm_vmalloc(ram_addr_t size);
+void *kvm_arch_vmalloc(ram_addr_t size);
 void kvm_setup_guest_memory(void *start, size_t size);
 
 int kvm_coalesce_mmio_region(target_phys_addr_t start, ram_addr_t size);