From a9d23e71d7716e394a772686bfd994f4e181b235 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Tue, 8 Mar 2016 12:21:41 +0100 Subject: s390/mm: shadow pages with real guest requested protection We really want to avoid manually handling protection for nested virtualization. By shadowing pages with the protection the guest asked us for, the SIE can handle most protection-related actions for us (e.g. special handling for MVPG) and we can directly forward protection exceptions to the guest. PTEs will now always be shadowed with the correct _PAGE_PROTECT flag. Unshadowing will take care of any guest changes to the parent PTE and any host changes to the host PTE. If the host PTE doesn't have the fitting access rights or is not available, we have to fix it up. Acked-by: Martin Schwidefsky Signed-off-by: David Hildenbrand Signed-off-by: Christian Borntraeger --- arch/s390/mm/pgtable.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) (limited to 'arch/s390/mm/pgtable.c') diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 5b02583fbf4c..293130b5aee7 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -463,29 +463,27 @@ int ptep_force_prot(struct mm_struct *mm, unsigned long addr, } int ptep_shadow_pte(struct mm_struct *mm, unsigned long saddr, - pte_t *sptep, pte_t *tptep, int write) + pte_t *sptep, pte_t *tptep, pte_t pte) { pgste_t spgste, tpgste; pte_t spte, tpte; int rc = -EAGAIN; + if (!(pte_val(*tptep) & _PAGE_INVALID)) + return 0; /* already shadowed */ spgste = pgste_get_lock(sptep); spte = *sptep; if (!(pte_val(spte) & _PAGE_INVALID) && - !(pte_val(spte) & _PAGE_PROTECT)) { - rc = 0; - if (!(pte_val(*tptep) & _PAGE_INVALID)) - /* Update existing mapping */ - ptep_flush_direct(mm, saddr, tptep); - else - rc = 1; + !((pte_val(spte) & _PAGE_PROTECT) && + !(pte_val(pte) & _PAGE_PROTECT))) { pgste_val(spgste) |= PGSTE_VSIE_BIT; tpgste = pgste_get_lock(tptep); pte_val(tpte) = (pte_val(spte) & PAGE_MASK) | - (write ? 0 : _PAGE_PROTECT); + (pte_val(pte) & _PAGE_PROTECT); /* don't touch the storage key - it belongs to parent pgste */ tpgste = pgste_set_pte(tptep, tpgste, tpte); pgste_set_unlock(tptep, tpgste); + rc = 1; } pgste_set_unlock(sptep, spgste); return rc; -- cgit v1.2.3