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iommu/amd: Introduce first_pte_l7() helper 

Given an arbitrary pte that is part of a large mapping, this function
returns the first pte of the series (and optionally the mapped size and
number of PTEs)
It will be re-used in a subsequent patch to replace an existing L7
mapping.

Fixes: 6d568ef9a6 ("iommu/amd: Allow downgrading page-sizes in alloc_pte()")
Signed-off-by: Andrei Dulea <adulea@amazon.de>
This commit is contained in:
Andrei Dulea 2019-09-13 16:42:30 +02:00 committed by Joerg Roedel
parent 6ccb72f837
commit 7f1f1683c1
1 changed files with 29 additions and 11 deletions
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40
drivers/iommu/amd_iommu.c
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@ -501,6 +501,29 @@ static void iommu_uninit_device(struct device *dev)
*/
}
/*
* Helper function to get the first pte of a large mapping
*/
static u64 *first_pte_l7(u64 *pte, unsigned long *page_size,
unsigned long *count)
{
unsigned long pte_mask, pg_size, cnt;
u64 *fpte;
pg_size = PTE_PAGE_SIZE(*pte);
cnt = PAGE_SIZE_PTE_COUNT(pg_size);
pte_mask = ~((cnt << 3) - 1);
fpte = (u64 *)(((unsigned long)pte) & pte_mask);
if (page_size)
*page_size = pg_size;
if (count)
*count = cnt;
return fpte;
}
/****************************************************************************
*
* Interrupt handling functions
@ -1567,17 +1590,12 @@ static u64 *fetch_pte(struct protection_domain *domain,
*page_size = PTE_LEVEL_PAGE_SIZE(level);
}
if (PM_PTE_LEVEL(*pte) == 0x07) {
unsigned long pte_mask;
/*
* If we have a series of large PTEs, make
* sure to return a pointer to the first one.
*/
*page_size = pte_mask = PTE_PAGE_SIZE(*pte);
pte_mask = ~((PAGE_SIZE_PTE_COUNT(pte_mask) << 3) - 1);
pte = (u64 *)(((unsigned long)pte) & pte_mask);
}
/*
* If we have a series of large PTEs, make
* sure to return a pointer to the first one.
*/
if (PM_PTE_LEVEL(*pte) == PAGE_MODE_7_LEVEL)
pte = first_pte_l7(pte, page_size, NULL);
return pte;
}