From 4b25423aee137f33f136f539af2d85c7df2b7566 Mon Sep 17 00:00:00 2001 From: Arianna Avanzini Date: Tue, 2 Sep 2014 01:47:34 +0200 Subject: [PATCH] arch/arm: unmap partially-mapped memory regions This commit modifies the function apply_p2m_changes() so that it destroys changes performed while mapping a memory region, if errors are seen during the operation. The implemented behaviour includes destroying only mappings created during the latest invocation of apply_p2m_changes(). This is useful to avoid that memory areas remain partially accessible to guests. Signed-off-by: Arianna Avanzini Cc: Dario Faggioli Cc: Paolo Valente Cc: Stefano Stabellini Cc: Julien Grall Cc: Ian Campbell Cc: Jan Beulich Cc: Keir Fraser Cc: Tim Deegan Cc: Ian Jackson Cc: Andrew Cooper Cc: Eric Trudeau Cc: Viktor Kleinik Cc: Andrii Tseglytskyi Acked-by: Ian Campbell --- xen/arch/arm/p2m.c | 41 ++++++++++++++++++++++++++++++----------- 1 file changed, 30 insertions(+), 11 deletions(-) diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c index 8f83d17df2..ede839da60 100644 --- a/xen/arch/arm/p2m.c +++ b/xen/arch/arm/p2m.c @@ -440,6 +440,14 @@ static bool_t is_mapping_aligned(const paddr_t start_gpaddr, #define P2M_ONE_PROGRESS_NOP 0x1 #define P2M_ONE_PROGRESS 0x10 +/* Helpers to lookup the properties of each level */ +static const paddr_t level_sizes[] = + { ZEROETH_SIZE, FIRST_SIZE, SECOND_SIZE, THIRD_SIZE }; +static const paddr_t level_masks[] = + { ZEROETH_MASK, FIRST_MASK, SECOND_MASK, THIRD_MASK }; +static const paddr_t level_shifts[] = + { ZEROETH_SHIFT, FIRST_SHIFT, SECOND_SHIFT, THIRD_SHIFT }; + /* * 0 == (P2M_ONE_DESCEND) continue to descend the tree * +ve == (P2M_ONE_PROGRESS_*) handled at this level, continue, flush, @@ -460,13 +468,6 @@ static int apply_one_level(struct domain *d, int mattr, p2m_type_t t) { - /* Helpers to lookup the properties of each level */ - const paddr_t level_sizes[] = - { ZEROETH_SIZE, FIRST_SIZE, SECOND_SIZE, THIRD_SIZE }; - const paddr_t level_masks[] = - { ZEROETH_MASK, FIRST_MASK, SECOND_MASK, THIRD_MASK }; - const paddr_t level_shifts[] = - { ZEROETH_SHIFT, FIRST_SHIFT, SECOND_SHIFT, THIRD_SHIFT }; const paddr_t level_size = level_sizes[level]; const paddr_t level_mask = level_masks[level]; const paddr_t level_shift = level_shifts[level]; @@ -713,7 +714,8 @@ static int apply_p2m_changes(struct domain *d, int rc, ret; struct p2m_domain *p2m = &d->arch.p2m; lpae_t *first = NULL, *second = NULL, *third = NULL; - paddr_t addr; + paddr_t addr, orig_maddr = maddr; + unsigned int level = 0; unsigned long cur_first_page = ~0, cur_first_offset = ~0, cur_second_offset = ~0; @@ -769,8 +771,9 @@ static int apply_p2m_changes(struct domain *d, * current hardware doesn't support super page mappings at * level 0 anyway */ + level = 1; ret = apply_one_level(d, &first[first_table_offset(addr)], - 1, flush_pt, op, + level, flush_pt, op, start_gpaddr, end_gpaddr, &addr, &maddr, &flush, mattr, t); @@ -790,8 +793,9 @@ static int apply_p2m_changes(struct domain *d, } /* else: second already valid */ + level = 2; ret = apply_one_level(d,&second[second_table_offset(addr)], - 2, flush_pt, op, + level, flush_pt, op, start_gpaddr, end_gpaddr, &addr, &maddr, &flush, mattr, t); @@ -809,8 +813,9 @@ static int apply_p2m_changes(struct domain *d, cur_second_offset = second_table_offset(addr); } + level = 3; ret = apply_one_level(d, &third[third_table_offset(addr)], - 3, flush_pt, op, + level, flush_pt, op, start_gpaddr, end_gpaddr, &addr, &maddr, &flush, mattr, t); @@ -844,6 +849,20 @@ out: if (third) unmap_domain_page(third); if (second) unmap_domain_page(second); if (first) unmap_domain_page(first); + if ( rc < 0 && ( op == INSERT || op == ALLOCATE ) && + addr != start_gpaddr ) + { + BUG_ON(addr == end_gpaddr); + /* + * addr keeps the address of the last successfully-inserted mapping, + * while apply_p2m_changes() considers an address range which is + * exclusive of end_gpaddr: add level_size to addr to obtain the + * right end of the range + */ + apply_p2m_changes(d, REMOVE, + start_gpaddr, addr + level_sizes[level], orig_maddr, + mattr, p2m_invalid); + } spin_unlock(&p2m->lock); -- 2.30.2