Re: [PATCH for-5.1 V4 1/4] hw/mips: Implement the kvm_type() hook in MachineClass

[Thomas Huth <thuth@redhat.com>]

On 15/06/2020 02.52, Huacai Chen wrote:
> Hi, Aleksandar,
> 
> On Sun, Jun 14, 2020 at 4:07 PM Aleksandar Markovic
> <aleksandar.qemu.devel@gmail.com> wrote:
>>
>>
>>
>> уто, 2. јун 2020. у 04:38 Huacai Chen <zltjiangshi@gmail.com> је написао/ла:
>>>
>>> MIPS has two types of KVM: TE & VZ, and TE is the default type. Now we
>>> can't create a VZ guest in QEMU because it lacks the kvm_type() hook in
>>> MachineClass. Besides, libvirt uses a null-machine to detect the kvm
>>> capability, so by default it will return "KVM not supported" on a VZ
>>> platform. Thus, null-machine also need the kvm_type() hook.
>>>
>>> Reviewed-by: Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
>>> Signed-off-by: Huacai Chen <chenhc@lemote.com>
>>> Co-developed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
>>> ---
>>
>> Huacai,
>>
>> Please take a look at Peter's remarks at:
>>
>> https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg01878.html
>>
>> ...and refactor this patch for v5. My general advice: The simpler, the batter.
>>
> OK, I will rework this patch.

 Hi,

is there maybe also a way to do this without moving null-machine.o from
common-obj-y to obj-y, and to avoid the target-specific hacks in this
file ? We just moved the null-machine from obj-y to common-obj-y two
years ago (see commit 3858ff763985fb9e), since it's more desirable to
have as much code in common-obj to save compilation time and maybe to be
able to link a qemu with more than one target CPU in one binary one day...

ppc64 has also more than one kvm_type (kvm-hv and kvm-pr), and
apparently it also works without hacks to the null-machine code there
... so maybe you can peek into the ppc64 code to see how it is solved there?

 Thomas


>>>  hw/core/Makefile.objs  |  2 +-
>>>  hw/core/null-machine.c |  4 ++++
>>>  hw/mips/Makefile.objs  |  2 +-
>>>  hw/mips/common.c       | 42 ++++++++++++++++++++++++++++++++++++++++++
>>>  include/hw/mips/mips.h |  3 +++
>>>  5 files changed, 51 insertions(+), 2 deletions(-)
>>>  create mode 100644 hw/mips/common.c
>>>
>>> diff --git a/hw/core/Makefile.objs b/hw/core/Makefile.objs
>>> index 1d540ed..b5672f4 100644
>>> --- a/hw/core/Makefile.objs
>>> +++ b/hw/core/Makefile.objs
>>> @@ -17,11 +17,11 @@ common-obj-$(CONFIG_SOFTMMU) += vm-change-state-handler.o
>>>  common-obj-$(CONFIG_SOFTMMU) += qdev-properties-system.o
>>>  common-obj-$(CONFIG_SOFTMMU) += sysbus.o
>>>  common-obj-$(CONFIG_SOFTMMU) += machine.o
>>> -common-obj-$(CONFIG_SOFTMMU) += null-machine.o
>>>  common-obj-$(CONFIG_SOFTMMU) += loader.o
>>>  common-obj-$(CONFIG_SOFTMMU) += machine-hmp-cmds.o
>>>  common-obj-$(CONFIG_SOFTMMU) += numa.o
>>>  common-obj-$(CONFIG_SOFTMMU) += clock-vmstate.o
>>> +obj-$(CONFIG_SOFTMMU) += null-machine.o
>>>  obj-$(CONFIG_SOFTMMU) += machine-qmp-cmds.o
>>>
>>>  common-obj-$(CONFIG_EMPTY_SLOT) += empty_slot.o
>>> diff --git a/hw/core/null-machine.c b/hw/core/null-machine.c
>>> index cb47d9d..94a36f9 100644
>>> --- a/hw/core/null-machine.c
>>> +++ b/hw/core/null-machine.c
>>> @@ -17,6 +17,7 @@
>>>  #include "sysemu/sysemu.h"
>>>  #include "exec/address-spaces.h"
>>>  #include "hw/core/cpu.h"
>>> +#include "hw/mips/mips.h"
>>>
>>>  static void machine_none_init(MachineState *mch)
>>>  {
>>> @@ -50,6 +51,9 @@ static void machine_none_machine_init(MachineClass *mc)
>>>      mc->max_cpus = 1;
>>>      mc->default_ram_size = 0;
>>>      mc->default_ram_id = "ram";
>>> +#ifdef TARGET_MIPS
>>> +    mc->kvm_type = mips_kvm_type;
>>> +#endif
>>>  }
>>>
>>>  DEFINE_MACHINE("none", machine_none_machine_init)
>>> diff --git a/hw/mips/Makefile.objs b/hw/mips/Makefile.objs
>>> index 739e2b7..3b3e6ea 100644
>>> --- a/hw/mips/Makefile.objs
>>> +++ b/hw/mips/Makefile.objs
>>> @@ -1,4 +1,4 @@
>>> -obj-y += addr.o mips_int.o
>>> +obj-y += addr.o common.o mips_int.o
>>>  obj-$(CONFIG_R4K) += r4k.o
>>>  obj-$(CONFIG_MALTA) += gt64xxx_pci.o malta.o
>>>  obj-$(CONFIG_MIPSSIM) += mipssim.o
>>> diff --git a/hw/mips/common.c b/hw/mips/common.c
>>> new file mode 100644
>>> index 0000000..4d8e141
>>> --- /dev/null
>>> +++ b/hw/mips/common.c
>>> @@ -0,0 +1,42 @@
>>> +/*
>>> + * Common MIPS routines
>>> + *
>>> + * Copyright (c) 2020 Huacai Chen (chenhc@lemote.com)
>>> + * This code is licensed under the GNU GPL v2.
>>> + */
>>> +
>>> +#include <linux/kvm.h>
>>> +#include "qemu/osdep.h"
>>> +#include "qemu-common.h"
>>> +#include "hw/boards.h"
>>> +#include "hw/mips/mips.h"
>>> +#include "sysemu/kvm_int.h"
>>> +
>>> +#ifndef CONFIG_KVM
>>> +
>>> +int mips_kvm_type(MachineState *machine, const char *vm_type)
>>> +{
>>> +    return 0;
>>> +}
>>> +
>>> +#else
>>> +
>>> +int mips_kvm_type(MachineState *machine, const char *vm_type)
>>> +{
>>> +    int r;
>>> +    KVMState *s = KVM_STATE(machine->accelerator);
>>> +
>>> +    r = kvm_check_extension(s, KVM_CAP_MIPS_VZ);
>>> +    if (r > 0) {
>>> +        return KVM_VM_MIPS_VZ;
>>> +    }
>>> +
>>> +    r = kvm_check_extension(s, KVM_CAP_MIPS_TE);
>>> +    if (r > 0) {
>>> +        return KVM_VM_MIPS_TE;
>>> +    }
>>> +
>>> +    return -1;
>>> +}
>>> +
>>> +#endif
>>> diff --git a/include/hw/mips/mips.h b/include/hw/mips/mips.h
>>> index 0af4c3d..2ac0580 100644
>>> --- a/include/hw/mips/mips.h
>>> +++ b/include/hw/mips/mips.h
>>> @@ -20,4 +20,7 @@ void rc4030_dma_write(void *dma, uint8_t *buf, int len);
>>>
>>>  DeviceState *rc4030_init(rc4030_dma **dmas, IOMMUMemoryRegion **dma_mr);
>>>
>>> +/* common.c */
>>> +int mips_kvm_type(MachineState *machine, const char *vm_type);
>>> +
>>>  #endif
>>> --
>>> 2.7.0
>>>
>