[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH RFC 6/9] xen: arm: handle variable p2m levels in p2m_lookup
This paves the way for boot-time selection of the number of levels to use in the p2m, which is required to support both 40-bit and 48-bit systems. For now the starting level remains a compile time constant. Implemented by turning the linear sequence of lookups into a loop. Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx> --- xen/arch/arm/p2m.c | 70 +++++++++++++++++++++++++++++++++------------------- 1 file changed, 45 insertions(+), 25 deletions(-) diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c index 225d125..557663f 100644 --- a/xen/arch/arm/p2m.c +++ b/xen/arch/arm/p2m.c @@ -149,45 +149,69 @@ static lpae_t *p2m_map_first(struct p2m_domain *p2m, paddr_t addr) paddr_t p2m_lookup(struct domain *d, paddr_t paddr, p2m_type_t *t) { struct p2m_domain *p2m = &d->arch.p2m; - lpae_t pte, *first = NULL, *second = NULL, *third = NULL; + const unsigned int offsets[4] = { + zeroeth_table_offset(paddr), + first_table_offset(paddr), + second_table_offset(paddr), + third_table_offset(paddr) + }; + const paddr_t masks[4] = { + ZEROETH_MASK, FIRST_MASK, SECOND_MASK, THIRD_MASK + }; + lpae_t pte, *map; paddr_t maddr = INVALID_PADDR; paddr_t mask; p2m_type_t _t; + int level, root_table; + + BUILD_BUG_ON(THIRD_MASK != PAGE_MASK); /* Allow t to be NULL */ t = t ?: &_t; *t = p2m_invalid; + if ( P2M_ROOT_PAGES > 1 ) + { + /* + * Concatenated root-level tables. The table number will be + * the offset at the previous level. It is not possible to + * concetenate a level-0 root. + */ + BUG_ON(P2M_ROOT_LEVEL == 0); + root_table = offsets[P2M_ROOT_LEVEL - 1]; + if ( root_table >= P2M_ROOT_PAGES ) + goto err; + } + else + root_table = 0; + spin_lock(&p2m->lock); - first = p2m_map_first(p2m, paddr); - if ( !first ) - goto err; + map = __map_domain_page(p2m->root + root_table); - mask = FIRST_MASK; - pte = first[first_table_offset(paddr)]; - if ( !p2m_table(pte) ) - goto done; + for ( level = P2M_ROOT_LEVEL ; level < 4 ; level++ ) + { + mask = masks[level]; - mask = SECOND_MASK; - second = map_domain_page(pte.p2m.base); - pte = second[second_table_offset(paddr)]; - if ( !p2m_table(pte) ) - goto done; + pte = map[offsets[level]]; - mask = THIRD_MASK; + if ( level == 3 && !p2m_table(pte) ) + /* Invalid, clobber the pte */ + pte.bits = 0; + if ( level == 3 || !p2m_table(pte) ) + /* Done */ + break; - BUILD_BUG_ON(THIRD_MASK != PAGE_MASK); + BUG_ON(level == 3); - third = map_domain_page(pte.p2m.base); - pte = third[third_table_offset(paddr)]; + /* Map for next level */ + unmap_domain_page(map); + map = map_domain_page(pte.p2m.base); + } - /* This bit must be one in the level 3 entry */ - if ( !p2m_table(pte) ) - pte.bits = 0; + unmap_domain_page(map); -done: if ( p2m_valid(pte) ) { ASSERT(pte.p2m.type != p2m_invalid); @@ -195,10 +219,6 @@ done: *t = pte.p2m.type; } - if (third) unmap_domain_page(third); - if (second) unmap_domain_page(second); - if (first) unmap_domain_page(first); - err: spin_unlock(&p2m->lock); -- 1.7.10.4 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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