diff options
| author | Janosch Frank | 2017-03-02 15:23:42 +0100 |
|---|---|---|
| committer | Martin Schwidefsky | 2017-03-02 17:17:16 +0100 |
| commit | 2e4d88009f57057df7672fa69a32b5224af54d37 (patch) | |
| tree | 06e098c4ba6b3f091a3262b60ff562069f73ee11 /arch | |
| parent | 7afbeb6df2aa5f9e3a0fc228817a85c16dea0faa (diff) | |
KVM: s390: Fix guest migration for huge guests resulting in panic
While we can technically not run huge page guests right now, we can
setup a guest with huge pages. Trying to migrate it will trigger a
VM_BUG_ON and, if the kernel is not configured to panic on a BUG, it
will happily try to work on non-existing page table entries.
With this patch, we always return "dirty" if we encounter a large page
when migrating. This at least fixes the immediate problem until we
have proper handling for both kind of pages.
Fixes: 15f36eb ("KVM: s390: Add proper dirty bitmap support to S390 kvm.")
Cc: <stable@vger.kernel.org> # 3.16+
Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/s390/mm/pgtable.c | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index b48dc5f1900b..463e5ef02304 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -608,12 +608,29 @@ void ptep_zap_key(struct mm_struct *mm, unsigned long addr, pte_t *ptep) bool test_and_clear_guest_dirty(struct mm_struct *mm, unsigned long addr) { spinlock_t *ptl; + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; pgste_t pgste; pte_t *ptep; pte_t pte; bool dirty; - ptep = get_locked_pte(mm, addr, &ptl); + pgd = pgd_offset(mm, addr); + pud = pud_alloc(mm, pgd, addr); + if (!pud) + return false; + pmd = pmd_alloc(mm, pud, addr); + if (!pmd) + return false; + /* We can't run guests backed by huge pages, but userspace can + * still set them up and then try to migrate them without any + * migration support. + */ + if (pmd_large(*pmd)) + return true; + + ptep = pte_alloc_map_lock(mm, pmd, addr, &ptl); if (unlikely(!ptep)) return false; |