[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v2 2/4] x86/mm: skip super-page alignment checks for non-present entries
INVALID_MFN is ~0, so by it having all bits as 1s it doesn't fulfill the super-page address alignment checks for L3 and L2 entries. Skip the alignment checks if the new entry is a non-present one. This fixes a regression introduced by 0b6b51a69f4d, where the switch from 0 to INVALID_MFN caused all super-pages to be shattered when attempting to remove mappings by passing INVALID_MFN instead of 0. Fixes: 0b6b51a69f4d ('xen/mm: Switch map_pages_to_xen to use MFN typesafe') Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx> --- Changes since v1: - Detect non-present entries from the flags contents rather than checking the mfn parameter. --- xen/arch/x86/mm.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index 8afb63c855b9..64b8054891da 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -5232,9 +5232,17 @@ int map_pages_to_xen( } \ } while (0) -/* Check if a (virt, mfn) tuple is aligned for a given slot level. */ -#define IS_LnE_ALIGNED(v, m, n) \ - IS_ALIGNED(PFN_DOWN(v) | mfn_x(m), (1UL << (PAGETABLE_ORDER * (n - 1))) - 1) +/* + * Check if a (virt, mfn) tuple is aligned for a given slot level. m must not + * be INVALID_MFN, since alignment is only relevant for present entries. + */ +#define IS_LnE_ALIGNED(v, m, n) ({ \ + mfn_t m_ = m; \ + \ + ASSERT(!mfn_eq(m_, INVALID_MFN)); \ + IS_ALIGNED(PFN_DOWN(v) | mfn_x(m_), \ + (1UL << (PAGETABLE_ORDER * (n - 1))) - 1); \ +}) #define IS_L2E_ALIGNED(v, m) IS_LnE_ALIGNED(v, m, 2) #define IS_L3E_ALIGNED(v, m) IS_LnE_ALIGNED(v, m, 3) @@ -5255,7 +5263,8 @@ int map_pages_to_xen( L3T_LOCK(current_l3page); ol3e = *pl3e; - if ( cpu_has_page1gb && IS_L3E_ALIGNED(virt, mfn) && + if ( cpu_has_page1gb && + (!(flags & _PAGE_PRESENT) || IS_L3E_ALIGNED(virt, mfn)) && nr_mfns >= (1UL << (L3_PAGETABLE_SHIFT - PAGE_SHIFT)) && !(flags & (_PAGE_PAT | MAP_SMALL_PAGES)) ) { @@ -5374,7 +5383,7 @@ int map_pages_to_xen( if ( !pl2e ) goto out; - if ( IS_L2E_ALIGNED(virt, mfn) && + if ( (!(flags & _PAGE_PRESENT) || IS_L2E_ALIGNED(virt, mfn)) && (nr_mfns >= (1u << PAGETABLE_ORDER)) && !(flags & (_PAGE_PAT|MAP_SMALL_PAGES)) ) { @@ -5544,7 +5553,8 @@ int map_pages_to_xen( check_l3: if ( cpu_has_page1gb && (flags == PAGE_HYPERVISOR) && - ((nr_mfns == 0) || IS_L3E_ALIGNED(virt, mfn)) ) + ((nr_mfns == 0) || !(flags & _PAGE_PRESENT) || + IS_L3E_ALIGNED(virt, mfn)) ) { unsigned long base_mfn; const l2_pgentry_t *l2t; -- 2.46.0
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