Re: [Qemu-devel] general question

[Max Filippov]

On Thu, May 31, 2012 at 1:21 PM, ���f任 (Wei-Ren Chen)
<address@hidden> wrote:
>> Hmmm, does it?
>>
>> void helper_invlpg(target_ulong addr)
>> {
>>     helper_svm_check_intercept_param(SVM_EXIT_INVLPG, 0);
>>     tlb_flush_page(env, addr);
>> }
>
>  I would be wrong, so let the code speak. ;)
>
> ---
> void tlb_flush_page(CPUArchState *env, target_ulong addr)
> {
>    if ((addr & env->tlb_flush_mask) == env->tlb_flush_addr) {

tlb_flush_addr/tlb_flush_mask is a region that covers all large pages;
this condition would be false if there are no large pages in the TLB or
the invalidation happens far enough from them.

>        tlb_flush(env, 1); --- (1)
>        return;
>    }
>
>    ... snip ...
>
>    addr &= TARGET_PAGE_MASK;
>    i = (addr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
>    for (mmu_idx = 0; mmu_idx < NB_MMU_MODES; mmu_idx++) {
>        tlb_flush_entry(&env->tlb_table[mmu_idx][i], addr);
>    }
>
>    tb_flush_jmp_cache(env, addr);
> }
> ---
>
>  The comment of tlb_flush (1) says,
>
>    QEMU doesn't currently implement a global/not-global flag
>    for tlb entries, at the moment tlb_flush() will also flush all
>    tlb entries in the flush_global == false case.
>
> That's why I get impression on QEMU flush the entire tlb. So it could flush
> particular tlb entry in tlb_flush_entry?

I'd say the probability is high with 32bit guest.

-- 
Thanks.
-- Max