Re: [PATCH v4] target/s390x: Implement the MVPG condition-code-option bit

[David Hildenbrand]

> Am 03.03.2021 um 22:05 schrieb Richard Henderson 
> <richard.henderson@linaro.org>:
> 
> On 3/3/21 11:39 AM, David Hildenbrand wrote:
>> Should we start wrapping that stuff into #ifdef CONFIG_TCG ?
>>> +    uint64_t tlb_fill_tec;   /* translation exception code during tlb_fill 
>>> */
>>> +    int tlb_fill_exc;        /* exception number seen during tlb_fill */
> 
> Eh, probably not.  At least not until we elide the softmmu tlb, which is 
> fantastically larger.
> 
>>> +    if (unlikely(flags & TLB_INVALID_MASK)) {
>>> +        return false;
>> ^ I recall PAGE_WRITE_INV handling where we immediately set TLB_INVALID_MASK 
>> again on write access (to handle low-address protection cleanly). I suspect 
>> that TLB_INVALID_MASK will be set in that case (I could be wrong, though).
>> What certainly would work is checking for "haddr != NULL".
>> /* Don't rely on TLB_INVALID_MASK - see PAGE_WRITE_INV handling. */
>> if (unlikely(!haddr1)) {
>>     return false;
>> }
> 
> Ah, right.  I consider TLB_INVALID_MASK being set in the return from 
> probe_access_flags for PAGE_WRITE_INV a bug.  I'm not sure how to fix that 
> right away.
> 
> Well, !haddr1 is also false for TLB_MMIO, so you'd need to check for that as 
> well.

MMIO on s390x? :)