Re: linux-next: manual merge of the kvm-ppc tree with thepowerpc-merge tree

From: Scott Wood
Date: Thu Oct 11 2012 - 11:50:07 EST


On 10/11/2012 08:04:58 AM, Alexander Graf wrote:

On 11.10.2012, at 05:32, Tabi Timur-B04825 wrote:

> On Wed, Oct 10, 2012 at 9:47 PM, Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:
>
>> Commit 549d62d889b4 ("KVM: PPC: use definitions in epapr header
>> for hcalls") from the kvm-ppc tree added an include of asm/epapr_hcall.h
>> to the user visible part of asm/kvm_para.h so asm/epapr_hcall.h became a
>> user visible header file.
>
> Any real user-space code that tries to call any of the functions in
> epapr_hcall.h will cause an exception.

Actually it'll cause a linker error, as of the "Don't use hardcoded opcode for ePAPR hcall invocation" patch.

> Claiming that kernel header files that KVM needs are suddenly
> user-space header files doesn't make much sense to me, but I guess
> it's not my decision.

This is about kvm_host.h, which is the part that is exported to user space. It usually contains constants and structs that are required for the API.

s/kvm_host/kvm_para/

I'm not sure anything in kvm_para.h or epapr_hcalls.h would be of use to userspace, but it would be of use to the guest OS, so it's still not kernel-internal.

The variable externs should be #ifdef __KERNEL__ as David points out. The asm stuff could still be useful in a guest OS if the guest provides epapr_hypercall_start.

-Scott
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