Re: [PATCH v2 4/7] x86/vmx: add do_vmtrace_op

[Jan Beulich <jbeulich@suse.com>]

On 22.06.2020 19:05, Michał Leszczyński wrote:
>>>>>> +struct xen_hvm_vmtrace_op {
>>>>>> +    /* IN variable */
>>>>>> +    uint32_t version;   /* HVMOP_VMTRACE_INTERFACE_VERSION */
>>>>>> +    uint32_t cmd;
>>>>>> +/* Enable/disable external vmtrace for given domain */
>>>>>> +#define HVMOP_vmtrace_ipt_enable      1
>>>>>> +#define HVMOP_vmtrace_ipt_disable     2
>>>>>> +#define HVMOP_vmtrace_ipt_get_offset  3
>>>>>> +    domid_t domain;
>>>>>> +    uint32_t vcpu;
>>>>>> +    uint64_t size;
>>>>>> +
>>>>>> +    /* OUT variable */
>>>>>> +    uint64_t offset;
>>>>>
>>>>> If this is to be a tools-only interface, please use uint64_aligned_t.
>>>>>
>>>>
>>>> This type is not defined within hvm_op.h header. What should I do about it?
>>>
>>> It gets defined by xen.h, so should be available here. Its
>>> definitions live in a
>>>
>>> #if defined(__XEN__) || defined(__XEN_TOOLS__)
>>>
>>> section, which is what I did recommend to put your interface in
>>> as well. Unless you want this to be exposed to the guest itself,
>>> at which point further constraints would arise.
>>>
> 
> When I've putted it into #if defined(__XEN__) || defined(__XEN_TOOLS__)
> then it complains about uint64_aligned_compat_t type missing.

One the interface is tools-only, the requirement for compat
checking isn't as strict anymore. As you can see from domctl
and sysctl, there's no checking there, but to compensate we
use uint64_aligned_t instead (arranging for struct layouts to
match).

> I also can't spot any single instance of uint64_aligned_t within
> this file.

That's unrelated.

Jan