Re: [PATCH 0/6] Adding the Android Emulator hypervisor driver accelerator

[Paolo Bonzini]

On 3/3/23 18:39, Haitao Shan wrote:
> > No, we're always open to new proposals. It merely means that it
> > might be harder to justify why the new hypervisor is a net benefit
> > for QEMU, when there is a competing solution supported by the OS
> > vendor.
>
> Thanks for the clarification. It is great that the door is not shut completely.

Hi,

sorry for not answering before.

I think in general QEMU should be open to merging work from the Android 
Emulator.  If AEHD is useful to the Android emulator, I would consider 
it interesting for QEMU as well.

However, I would rather have it as an extension to KVM if possible 
rather than a completely new emulator.  One possibility is to introduce 
a new file that encapsulates all KVM ioctls, with a struct that 
encapsulates the Unix file descriptor/Windows HANDLE.  For example

int kvm_ioctl_get_supported_cpuid(KVMState *s, struct kvm_cpuid *cpuid,
                                  int max)
{
    cpuid->nent = max;
#ifdef CONFIG_POSIX
    return ioctl(s, KVM_GET_SUPPORTED_VCPUID, cpuid);
#else
    size_t size = sizeof(*cpuid) + max * sizeof(*cpuid->entries);
    return aehd_ioctl(s, AEHD_GET_SUPPORTED_CPUID, cpuid, size, cpuid, 
size);
#endif
}

int kvm_ioctl_create_vcpu(KVMState *s, int vcpu_id, CPUState *out)
{
#ifdef CONFIG_POSIX
    out.kvm_fd = kvm_vm_ioctl(KVM_CREATE_VCPU, vcpu_id);
    return out.kvm_fd;
#else
    return aehd_vm_ioctl(s, AEHD_CREATE_VCPU, &vcpu_id, sizeof(vcpu_id),
                         &out.kvm_fd, sizeof(out.kvm_fd));
#endif
}

etc.

These are just general examples, the actual level of abstraction is up 
to you.

Paolo