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Re: [PATCH V3 (resend) 13/19] x86/setup: Do not create valid mappings when directmap=no


  • To: Elias El Yandouzi <eliasely@xxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Wed, 15 May 2024 17:50:53 +0200
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  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx, julien@xxxxxxx, pdurrant@xxxxxxxxxx, dwmw@xxxxxxxxxx, Hongyan Xia <hongyxia@xxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Julien Grall <jgrall@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
  • Delivery-date: Wed, 15 May 2024 15:51:07 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 14.05.2024 17:39, Roger Pau Monné wrote:
> On Mon, May 13, 2024 at 01:40:40PM +0000, Elias El Yandouzi wrote:
>> +        {
>> +            l4_pgentry_t *pl4e = &idle_pg_table[l4_table_offset(vaddr)];
>> +
>> +            if ( !(l4e_get_flags(*pl4e) & _PAGE_PRESENT) )
>> +            {
>> +                mfn_t mfn = alloc_boot_pages(1, 1);
> 
> Hm, why not use alloc_xen_pagetable()?
> 
>> +                void *v = map_domain_page(mfn);
>> +
>> +                clear_page(v);
>> +                UNMAP_DOMAIN_PAGE(v);
> 
> Maybe use clear_domain_page()?

Or else use unmap_domain_page(). v is going out of scope just afterwards,
and UNMAP_DOMAIN_PAGE() is intended to be use when that's not the case.

Jan



 


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