Re: [PATCH 07/10] x86/shadow: the guess_wrmap() hook is needed for HVM only

[Jan Beulich <jbeulich@xxxxxxxx>]

On 18.04.2020 11:03, Tim Deegan wrote:
> At 16:28 +0200 on 17 Apr (1587140897), Jan Beulich wrote:
>> sh_remove_write_access() bails early for !external guests, and hence its
>> building and thus the need for the hook can be suppressed altogether in
>> !HVM configs.
>>
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
>> @@ -366,6 +367,14 @@ int sh_validate_guest_entry(struct vcpu
>>  extern int sh_remove_write_access(struct domain *d, mfn_t readonly_mfn,
>>                                    unsigned int level,
>>                                    unsigned long fault_addr);
>> +#else
>> +static inline int sh_remove_write_access(struct domain *d, mfn_t 
>> readonly_mfn,
>> +                                         unsigned int level,
>> +                                         unsigned long fault_addr)
>> +{
> 
> Can we have an ASSERT(!shadow_mode_refcounts(d)) here, please,
> matching the check that would have made it a noop before?

I've added one, but I find this quite odd in a !HVM build, where

#define PG_refcounts   0

and

#define paging_mode_refcounts(_d) (!!((_d)->arch.paging.mode & PG_refcounts))

Perhaps you're wanting this mainly for documentation purposes?

Jan