Re: [Qemu-devel] [PATCH v10 08/10] hw/arm/virt: Implement kvm_type function for 4.0 machine

[Auger Eric <eric.auger@redhat.com>]

Hi Igor,

On 2/28/19 5:19 PM, Igor Mammedov wrote:
> On Thu, 28 Feb 2019 16:03:22 +0100
> Eric Auger <eric.auger@redhat.com> wrote:
> 
>> This patch implements the machine class kvm_type() callback.
>> It returns the number of bits requested to implement the whole GPA
>> range including the RAM and IO regions located beyond.
>> The returned value in passed though the KVM_CREATE_VM ioctl and
>> this allows KVM to set the stage2 tables dynamically.
>>
>> To compute the highest GPA used in the memory map, kvm_type()
>> must freeze the memory map by calling virt_set_memmap().
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>>
>> ---
>> v7 -> v8:
>> - remove vmc->no_extended_memmap and vms->extended_memmap
>>
>> v6 -> v7:
>> - Introduce RAMBASE and rename add LEGACY_ prefix in that patch
>> - use local variables with explicit names in virt_set_memmap:
>>   device_memory_base, device_memory_size
>> - add an extended_memmap field in the class
>>
>> v5 -> v6:
>> - add some comments
>> - high IO region cannot start before 256GiB
>> ---
>>  hw/arm/virt.c | 39 ++++++++++++++++++++++++++++++++++++++-
>>  1 file changed, 38 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
>> index d7aa7d3f9d..7a158571b7 100644
>> --- a/hw/arm/virt.c
>> +++ b/hw/arm/virt.c
>> @@ -1439,7 +1439,13 @@ static void machvirt_init(MachineState *machine)
>>      bool firmware_loaded = bios_name || drive_get(IF_PFLASH, 0, 0);
>>      bool aarch64 = true;
>>  
>> -    virt_set_memmap(vms);
>> +    /*
>> +     * In accelerated mode, the memory map is computed in kvm_type()
> s/in/earlier in/
> 
>> +     * to create a VM with the right number of IPA bits.
>> +     */
>> +    if (!kvm_enabled()) {
> maybe check not for KVM but for vms->memmap == NULL
> so it would match with comment and be clear that we initializing memmap
> because nobody else did it yet.
> 
>> +        virt_set_memmap(vms);
>> +    }
>>  
>>      /* We can probe only here because during property set
>>       * KVM is not available yet
>> @@ -1828,6 +1834,36 @@ static HotplugHandler *virt_machine_get_hotplug_handler(MachineState *machine,
>>      return NULL;
>>  }
>>  
>> +/*
>> + * for arm64 kvm_type [7-0] encodes the requested number of bits
>> + * in the IPA address space
>> + */
>> +static int virt_kvm_type(MachineState *ms, const char *type_str)
>> +{
>> +    VirtMachineState *vms = VIRT_MACHINE(ms);
>> +    int max_vm_pa_size = kvm_arm_get_max_vm_ipa_size(ms);
>> +    int requested_pa_size;
>> +
>> +    /* we freeze the memory map to compute the highest gpa */
>> +    virt_set_memmap(vms);
>> +
> 
>> +    requested_pa_size = 64 - clz64(vms->highest_gpa);
>> +
>> +    if (requested_pa_size > max_vm_pa_size) {
>> +        error_report("-m and ,maxmem option values "
>> +                     "require an IPA range (%d bits) larger than "
>> +                     "the one supported by the host (%d bits)",
>> +                     requested_pa_size, max_vm_pa_size);
>> +       exit(1);
>> +    }
> this part is recurring pattern, is it worth using a helper function?
in TCG mode the message is different because this issue stems from the
fact the VCPU does not support a large enough PA range whereas here the
host kernel does not support large enough IPA. So I tend to keep the
code as is.

Thanks

Eric
> 
>> +    /*
>> +     * By default we return 0 which corresponds to an implicit legacy
>> +     * 40b IPA setting. Otherwise we return the actual requested PA
>> +     * logsize
>> +     */
>> +    return requested_pa_size > 40 ? requested_pa_size : 0;
>> +}
>> +
>>  static void virt_machine_class_init(ObjectClass *oc, void *data)
>>  {
>>      MachineClass *mc = MACHINE_CLASS(oc);
>> @@ -1852,6 +1888,7 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
>>      mc->cpu_index_to_instance_props = virt_cpu_index_to_props;
>>      mc->default_cpu_type = ARM_CPU_TYPE_NAME("cortex-a15");
>>      mc->get_default_cpu_node_id = virt_get_default_cpu_node_id;
>> +    mc->kvm_type = virt_kvm_type;
>>      assert(!mc->get_hotplug_handler);
>>      mc->get_hotplug_handler = virt_machine_get_hotplug_handler;
>>      hc->plug = virt_machine_device_plug_cb;
>