[Xen-devel] what's the purpose of line page table (PML4 entry 25

To:	xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject:	[Xen-devel] what's the purpose of line page table (PML4 entry 258)
From:	weiming <zephyr.zhao@xxxxxxxxx>
Date:	Sun, 30 Mar 2008 23:41:59 -0700
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Hi,

When I read the code of do_update_va_mapping, I find that it update the pte entry in the line page table by looking up the line page table via guest_map_l1e() :

2998 int do_update_va_mapping(unsigned long va, u64 val64,

2999                          unsigned long flags)
3000 {

3001     l1_pgentry_t   val = l1e_from_intpte(val64);

3002     struct vcpu   *v   = current;

3003     struct domain *d   = v->domain;

3004     l1_pgentry_t  *pl1e;
3005     unsigned long  vmask, bmap_ptr, gl1mfn;

3006     cpumask_t      pmask;
3007     int            rc  = 0;

3008 
3009     perfc_incr(calls_to_update_va);

3010 
3011     if ( unlikely(!__addr_ok(va) && !paging_mode_external(d)) )

3012         return -EINVAL;
3013 

3014     rc = xsm_update_va_mapping(current->domain, val);

3015     if ( rc )
3016         return rc;

3017 
3018     LOCK_BIGLOCK(d);

3019 
3020     pl1e = guest_map_l1e(v, va, &gl1mfn);

...
...

what's the purpose of this table?

Thanks

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[Xen-devel] what's the purpose of line page table (PML4 entry 258)