Re: [PATCH 03/16] KVM-HDR: KVM Userspace registering ioctl

[Avi Kivity <avi@redhat.com>]

On 01/24/2011 08:06 PM, Glauber Costa wrote:
> KVM, which stands for KVM Virtual Memory (I wanted to call it KVM Virtual Mojito),
> is a piece of shared memory that is visible to both the hypervisor and the guest
> kernel - but not the guest userspace.
>
> The basic idea is that the guest can tell the hypervisor about a specific
> piece of memory, and what it expects to find in there. This is a generic
> abstraction, that goes to userspace (qemu) if KVM (the hypervisor) can't
> handle a specific request, thus giving us flexibility in some features
> in the future.
>
> KVM (The hypervisor) can change the contents of this piece of memory at
> will. This works well with paravirtual information, and hopefully
> normal guest memory - like last update time for the watchdog, for
> instance.
>
> This patch contains the header part of the userspace communication implementation.
> Userspace can query the presence/absence of this feature in the normal way.
> It also tells the hypervisor that it is capable of handling - in whatever
> way it chooses, registrations that the hypervisor does not know how to.
> In x86, only user so far, this mechanism is implemented as generic userspace
> msr exit, that could theorectically be used to implement msr-handling in
> userspace.
>
> I am keeping the headers separate to facilitate backports to people
> who wants to backport the kernel part but not the hypervisor, or the other way around.
>

Again the protocol is not specified.  How about starting from 
Documentation/kvm/api.txt so we don't have to guess?

> diff --git a/include/linux/kvm.h b/include/linux/kvm.h
> index ea2dc1a..5cc4fe8 100644
> --- a/include/linux/kvm.h
> +++ b/include/linux/kvm.h
> @@ -161,6 +161,7 @@ struct kvm_pit_config {
>   #define KVM_EXIT_NMI              16
>   #define KVM_EXIT_INTERNAL_ERROR   17
>   #define KVM_EXIT_OSI              18
> +#define KVM_EXIT_X86_MSR_OP	  19

>
>   /*
> @@ -541,6 +551,7 @@ struct kvm_ppc_pvinfo {
>   #define KVM_CAP_PPC_GET_PVINFO 57
>   #define KVM_CAP_PPC_IRQ_LEVEL 58
>   #define KVM_CAP_ASYNC_PF 59
> +#define KVM_CAP_REGISTER_MEM_AREA 60

These two seem completely unrelated.


-- 
error compiling committee.c: too many arguments to function