linux-kernel - Re: [PATCH 6/8] kvm/mmu: add support for another level to page walker

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Date:	Mon, 22 Jun 2009 11:38:13 +0200
From:	Joerg Roedel <joerg.roedel@....com>
To:	Avi Kivity <avi@...hat.com>
CC:	Marcelo Tosatti <marcelo@...ck.org>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/8] kvm/mmu: add support for another level to page
	walker

On Sat, Jun 20, 2009 at 02:19:48PM +0300, Avi Kivity wrote:
> On 06/19/2009 04:16 PM, Joerg Roedel wrote:
>> The page walker may be used with nested paging too when accessing mmio areas.
>> Make it support the additional page-level too.
>>
>> Signed-off-by: Joerg Roedel<joerg.roedel@....com>
>> ---
>>   arch/x86/kvm/mmu.c         |    6 ++++++
>>   arch/x86/kvm/paging_tmpl.h |   16 ++++++++++++++++
>>   2 files changed, 22 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
>> index ef2396d..fc0e2fc 100644
>> --- a/arch/x86/kvm/mmu.c
>> +++ b/arch/x86/kvm/mmu.c
>> @@ -117,6 +117,11 @@ module_param(oos_shadow, bool, 0644);
>>   #define PT64_DIR_BASE_ADDR_MASK \
>>   	(PT64_BASE_ADDR_MASK&  ~((1ULL<<  (PAGE_SHIFT + PT64_LEVEL_BITS)) - 1))
>>
>> +#define PT64_PDPE_BASE_ADDR_MASK \
>> +	(PT64_BASE_ADDR_MASK&  ~(1ULL<<  (PAGE_SHIFT + (2 * PT64_LEVEL_BITS))))
>> +#define PT64_PDPE_OFFSET_MASK \
>> +	(PT64_BASE_ADDR_MASK&  (1ULL<<  (PAGE_SHIFT + (2 * PT64_LEVEL_BITS))))
>> +
>>   #define PT32_BASE_ADDR_MASK PAGE_MASK
>>   #define PT32_DIR_BASE_ADDR_MASK \
>>   	(PAGE_MASK&  ~((1ULL<<  (PAGE_SHIFT + PT32_LEVEL_BITS)) - 1))
>> @@ -130,6 +135,7 @@ module_param(oos_shadow, bool, 0644);
>>   #define PFERR_RSVD_MASK (1U<<  3)
>>   #define PFERR_FETCH_MASK (1U<<  4)
>> +static gfn_t gpte_to_gfn_pdpe(pt_element_t gpte)
>> +{
>> +	return (gpte&  PT64_PDPE_BASE_ADDR_MASK)>>  PAGE_SHIFT;
>> +}
>> +
>>   static bool FNAME(cmpxchg_gpte)(struct kvm *kvm,
>>   			 gfn_t table_gfn, unsigned index,
>>   			 pt_element_t orig_pte, pt_element_t new_pte)
>> @@ -201,6 +207,15 @@ walk:
>>   			break;
>>   		}
>>
>> +		if (walker->level == PT_PDPE_LEVEL&&
>> +		    (pte&  PT_PAGE_SIZE_MASK)&&
>> +		    is_long_mode(vcpu)) {
>> +			walker->gfn  = gpte_to_gfn_pdpe(pte);
>> +			walker->gfn += (addr&  PT64_PDPE_OFFSET_MASK)
>> +					>>  PAGE_SHIFT;
>> +			break;
>> +		}
>> +
>>   		pt_access = pte_access;
>>    
>
> It would be cleaner to merge this with the 2MB check earlier (and to  
> rename and parametrise gpte_to_gfn_pde() rather than duplicate it).

Ok, I will merge it into the previous function.

Joerg

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