Commit 09c6c754 authored by Janosch Frank's avatar Janosch Frank Committed by Cornelia Huck
Browse files

s390x: Enable KVM huge page backing support 



QEMU has had huge page support for a longer time already, but KVM
memory management under s390x needed some changes to work with huge
backings.

Now that we have support, let's enable it if requested and
available. Otherwise we now properly tell the user if there is no
support and back out instead of failing to run the VM later on.

Signed-off-by: default avatarJanosch Frank <frankja@linux.ibm.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Message-Id: <20180802070201.257406-1-frankja@linux.ibm.com>
Reviewed-by: default avatarThomas Huth <thuth@redhat.com>
Signed-off-by: default avatarCornelia Huck <cohuck@redhat.com>
parent 27e84d4e

target/s390x/kvm.c

+33 −2
Original line number Diff line number Diff line
@@ -34,6 +34,8 @@ 
#include "qapi/error.h"

#include "qemu/error-report.h"

#include "qemu/timer.h"

#include "qemu/units.h"

#include "qemu/mmap-alloc.h"

#include "sysemu/sysemu.h"

#include "sysemu/hw_accel.h"

#include "hw/hw.h"
@@ -139,6 +141,7 @@ static int cap_mem_op; 
static int cap_s390_irq;

static int cap_ri;

static int cap_gs;

static int cap_hpage_1m;



static int active_cmma;
@@ -220,9 +223,9 @@ static void kvm_s390_enable_cmma(void) 
        .attr = KVM_S390_VM_MEM_ENABLE_CMMA,

    };



    if (mem_path) {

    if (cap_hpage_1m) {

        warn_report("CMM will not be enabled because it is not "

                    "compatible with hugetlbfs.");

                    "compatible with huge memory backings.");

        return;

    }

    rc = kvm_vm_ioctl(kvm_state, KVM_SET_DEVICE_ATTR, &attr);
@@ -281,10 +284,38 @@ void kvm_s390_crypto_reset(void) 
    }

}



static int kvm_s390_configure_mempath_backing(KVMState *s)

{

    size_t path_psize = qemu_mempath_getpagesize(mem_path);



    if (path_psize == 4 * KiB) {

        return 0;

    }



    if (path_psize != 1 * MiB) {

        error_report("Memory backing with 2G pages was specified, "

                     "but KVM does not support this memory backing");

        return -EINVAL;

    }



    if (kvm_vm_enable_cap(s, KVM_CAP_S390_HPAGE_1M, 0)) {

        error_report("Memory backing with 1M pages was specified, "

                     "but KVM does not support this memory backing");

        return -EINVAL;

    }



    cap_hpage_1m = 1;

    return 0;

}



int kvm_arch_init(MachineState *ms, KVMState *s)

{

    MachineClass *mc = MACHINE_GET_CLASS(ms);



    if (mem_path && kvm_s390_configure_mempath_backing(s)) {

        return -EINVAL;

    }



    mc->default_cpu_type = S390_CPU_TYPE_NAME("host");

    cap_sync_regs = kvm_check_extension(s, KVM_CAP_SYNC_REGS);

    cap_async_pf = kvm_check_extension(s, KVM_CAP_ASYNC_PF);