kernel.git/arch/s390/include/asm/pgtable.h, branch linux-4.19.y

s390/mm: properly clear _PAGE_NOEXEC bit when it is not supported

2019-12-17T19:34:57Z

commit ab874f22d35a8058d8fdee5f13eb69d8867efeae upstream. On older HW or under a hypervisor, w/o the instruction-execution- protection (IEP) facility, and also w/o EDAT-1, a translation-specification exception may be recognized when bit 55 of a pte is one (_PAGE_NOEXEC). The current code tries to prevent setting _PAGE_NOEXEC in such cases, by removing it within set_pte_at(). However, ptep_set_access_flags() will modify a pte directly, w/o using set_pte_at(). There is at least one scenario where this can result in an active pte with _PAGE_NOEXEC set, which would then lead to a panic due to a translation-specification exception (write to swapped out page): do_swap_page pte = mk_pte (with _PAGE_NOEXEC bit) set_pte_at (will remove _PAGE_NOEXEC bit in page table, but keep it in local variable pte) vmf->orig_pte = pte (pte still contains _PAGE_NOEXEC bit) do_wp_page wp_page_reuse entry = vmf->orig_pte (still with _PAGE_NOEXEC bit) ptep_set_access_flags (writes entry with _PAGE_NOEXEC bit) Fix this by clearing _PAGE_NOEXEC already in mk_pte_phys(), where the pgprot value is applied, so that no pte with _PAGE_NOEXEC will ever be visible, if it is not supported. The check in set_pte_at() can then also be removed. Cc: # 4.11+ Fixes: 57d7f939e7bd ("s390: add no-execute support") Signed-off-by: Gerald Schaefer Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390/mm: fix mis-accounting of pgtable_bytes

2018-11-27T15:13:03Z

[ Upstream commit e12e4044aede97974f2222eb7f0ed726a5179a32 ] In case a fork or a clone system fails in copy_process and the error handling does the mmput() at the bad_fork_cleanup_mm label, the following warning messages will appear on the console: BUG: non-zero pgtables_bytes on freeing mm: 16384 The reason for that is the tricks we play with mm_inc_nr_puds() and mm_inc_nr_pmds() in init_new_context(). A normal 64-bit process has 3 levels of page table, the p4d level and the pud level are folded. On process termination the free_pud_range() function in mm/memory.c will subtract 16KB from pgtable_bytes with a mm_dec_nr_puds() call, but there actually is not really a pud table. One issue with this is the fact that pgtable_bytes is usually off by a few kilobytes, but the more severe problem is that for a failed fork or clone the free_pgtables() function is not called. In this case there is no mm_dec_nr_puds() or mm_dec_nr_pmds() that go together with the mm_inc_nr_puds() and mm_inc_nr_pmds in init_new_context(). The pgtable_bytes will be off by 16384 or 32768 bytes and we get the BUG message. The message itself is purely cosmetic, but annoying. To fix this override the mm_pmd_folded, mm_pud_folded and mm_p4d_folded function to check for the true size of the address space. Reported-by: Li Wang Tested-by: Li Wang Signed-off-by: Martin Schwidefsky Signed-off-by: Sasha Levin

s390/mm: Add huge page dirty sync support

2018-07-30T10:20:18Z

To do dirty loging with huge pages, we protect huge pmds in the gmap. When they are written to, we unprotect them and mark them dirty. We introduce the function gmap_test_and_clear_dirty_pmd which handles dirty sync for huge pages. Signed-off-by: Janosch Frank Acked-by: David Hildenbrand

s390/mm: Add gmap pmd invalidation and clearing

2018-07-30T10:20:17Z

If the host invalidates a pmd, we also have to invalidate the corresponding gmap pmds, as well as flush them from the TLB. This is necessary, as we don't share the pmd tables between host and guest as we do with ptes. The clearing part of these three new functions sets a guest pmd entry to _SEGMENT_ENTRY_EMPTY, so the guest will fault on it and we will re-link it. Flushing the gmap is not necessary in the host's lazy local and csp cases. Both purge the TLB completely. Signed-off-by: Janosch Frank Reviewed-by: Martin Schwidefsky Acked-by: David Hildenbrand

s390/mm: Add gmap pmd linking

2018-07-30T10:20:17Z

Let's allow pmds to be linked into gmap for the upcoming s390 KVM huge page support. Before this patch we copied the full userspace pmd entry. This is not correct, as it contains SW defined bits that might be interpreted differently in the GMAP context. Now we only copy over all hardware relevant information leaving out the software bits. Signed-off-by: Janosch Frank Reviewed-by: David Hildenbrand

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2018-06-12T18:34:04Z

Pull KVM updates from Paolo Bonzini: "Small update for KVM: ARM: - lazy context-switching of FPSIMD registers on arm64 - "split" regions for vGIC redistributor s390: - cleanups for nested - clock handling - crypto - storage keys - control register bits x86: - many bugfixes - implement more Hyper-V super powers - implement lapic_timer_advance_ns even when the LAPIC timer is emulated using the processor's VMX preemption timer. - two security-related bugfixes at the top of the branch" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (79 commits) kvm: fix typo in flag name kvm: x86: use correct privilege level for sgdt/sidt/fxsave/fxrstor access KVM: x86: pass kvm_vcpu to kvm_read_guest_virt and kvm_write_guest_virt_system KVM: x86: introduce linear_{read,write}_system kvm: nVMX: Enforce cpl=0 for VMX instructions kvm: nVMX: Add support for "VMWRITE to any supported field" kvm: nVMX: Restrict VMX capability MSR changes KVM: VMX: Optimize tscdeadline timer latency KVM: docs: nVMX: Remove known limitations as they do not exist now KVM: docs: mmu: KVM support exposing SLAT to guests kvm: no need to check return value of debugfs_create functions kvm: Make VM ioctl do valloc for some archs kvm: Change return type to vm_fault_t KVM: docs: mmu: Fix link to NPT presentation from KVM Forum 2008 kvm: x86: Amend the KVM_GET_SUPPORTED_CPUID API documentation KVM: x86: hyperv: declare KVM_CAP_HYPERV_TLBFLUSH capability KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE}_EX implementation KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE} implementation KVM: introduce kvm_make_vcpus_request_mask() API KVM: x86: hyperv: do rep check for each hypercall separately ...

mm: introduce ARCH_HAS_PTE_SPECIAL

2018-06-08T00:34:35Z

Currently the PTE special supports is turned on in per architecture header files. Most of the time, it is defined in arch/*/include/asm/pgtable.h depending or not on some other per architecture static definition. This patch introduce a new configuration variable to manage this directly in the Kconfig files. It would later replace __HAVE_ARCH_PTE_SPECIAL. Here notes for some architecture where the definition of __HAVE_ARCH_PTE_SPECIAL is not obvious: arm __HAVE_ARCH_PTE_SPECIAL which is currently defined in arch/arm/include/asm/pgtable-3level.h which is included by arch/arm/include/asm/pgtable.h when CONFIG_ARM_LPAE is set. So select ARCH_HAS_PTE_SPECIAL if ARM_LPAE. powerpc __HAVE_ARCH_PTE_SPECIAL is defined in 2 files: - arch/powerpc/include/asm/book3s/64/pgtable.h - arch/powerpc/include/asm/pte-common.h The first one is included if (PPC_BOOK3S & PPC64) while the second is included in all the other cases. So select ARCH_HAS_PTE_SPECIAL all the time. sparc: __HAVE_ARCH_PTE_SPECIAL is defined if defined(__sparc__) && defined(__arch64__) which are defined through the compiler in sparc/Makefile if !SPARC32 which I assume to be if SPARC64. So select ARCH_HAS_PTE_SPECIAL if SPARC64 There is no functional change introduced by this patch. Link: http://lkml.kernel.org/r/1523433816-14460-2-git-send-email-ldufour@linux.vnet.ibm.com Signed-off-by: Laurent Dufour Suggested-by: Jerome Glisse Reviewed-by: Jerome Glisse Acked-by: David Rientjes Cc: Michal Hocko Cc: "Aneesh Kumar K . V" Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Jonathan Corbet Cc: Catalin Marinas Cc: Will Deacon Cc: Yoshinori Sato Cc: Rich Felker Cc: David S. Miller Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Vineet Gupta Cc: Palmer Dabbelt Cc: Albert Ou Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: David Rientjes Cc: Robin Murphy Cc: Christophe LEROY Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

KVM: s390: Add storage key facility interpretation control

2018-05-17T07:00:41Z

Up to now we always expected to have the storage key facility available for our (non-VSIE) KVM guests. For huge page support, we need to be able to disable it, so let's introduce that now. We add the use_skf variable to manage KVM storage key facility usage. Also we rename use_skey in the mm context struct to uses_skeys to make it more clear that it is an indication that the vm actively uses storage keys. Signed-off-by: Janosch Frank Reviewed-by: Farhan Ali Reviewed-by: David Hildenbrand Acked-by: Christian Borntraeger Signed-off-by: Christian Borntraeger

s390/mm: modify pmdp_invalidate to return old value.

2018-02-01T01:18:38Z

It's required to avoid losing dirty and accessed bits. Link: http://lkml.kernel.org/r/20171213105756.69879-8-kirill.shutemov@linux.intel.com Signed-off-by: Martin Schwidefsky Signed-off-by: Kirill A. Shutemov Cc: Vlastimil Babka Cc: Andrea Arcangeli Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Revert "mm: replace p??_write with pte_access_permitted in fault + gup paths"

2017-12-16T02:53:22Z

This reverts commits 5c9d2d5c269c, c7da82b894e9, and e7fe7b5cae90. We'll probably need to revisit this, but basically we should not complicate the get_user_pages_fast() case, and checking the actual page table protection key bits will require more care anyway, since the protection keys depend on the exact state of the VM in question. Particularly when doing a "remote" page lookup (ie in somebody elses VM, not your own), you need to be much more careful than this was. Dave Hansen says: "So, the underlying bug here is that we now a get_user_pages_remote() and then go ahead and do the p*_access_permitted() checks against the current PKRU. This was introduced recently with the addition of the new p??_access_permitted() calls. We have checks in the VMA path for the "remote" gups and we avoid consulting PKRU for them. This got missed in the pkeys selftests because I did a ptrace read, but not a *write*. I also didn't explicitly test it against something where a COW needed to be done" It's also not entirely clear that it makes sense to check the protection key bits at this level at all. But one possible eventual solution is to make the get_user_pages_fast() case just abort if it sees protection key bits set, which makes us fall back to the regular get_user_pages() case, which then has a vma and can do the check there if we want to. We'll see. Somewhat related to this all: what we _do_ want to do some day is to check the PAGE_USER bit - it should obviously always be set for user pages, but it would be a good check to have back. Because we have no generic way to test for it, we lost it as part of moving over from the architecture-specific x86 GUP implementation to the generic one in commit e585513b76f7 ("x86/mm/gup: Switch GUP to the generic get_user_page_fast() implementation"). Cc: Peter Zijlstra Cc: Dan Williams Cc: Dave Hansen Cc: Kirill A. Shutemov Cc: "Jérôme Glisse" Cc: Andrew Morton Cc: Al Viro Signed-off-by: Linus Torvalds