1. 19 3月, 2018 7 次提交
  2. 17 2月, 2018 1 次提交
    • W
      arm64: mm: Use READ_ONCE/WRITE_ONCE when accessing page tables · 20a004e7
      Will Deacon 提交于
      In many cases, page tables can be accessed concurrently by either another
      CPU (due to things like fast gup) or by the hardware page table walker
      itself, which may set access/dirty bits. In such cases, it is important
      to use READ_ONCE/WRITE_ONCE when accessing page table entries so that
      entries cannot be torn, merged or subject to apparent loss of coherence
      due to compiler transformations.
      
      Whilst there are some scenarios where this cannot happen (e.g. pinned
      kernel mappings for the linear region), the overhead of using READ_ONCE
      /WRITE_ONCE everywhere is minimal and makes the code an awful lot easier
      to reason about. This patch consistently uses these macros in the arch
      code, as well as explicitly namespacing pointers to page table entries
      from the entries themselves by using adopting a 'p' suffix for the former
      (as is sometimes used elsewhere in the kernel source).
      Tested-by: NYury Norov <ynorov@caviumnetworks.com>
      Tested-by: NRichard Ruigrok <rruigrok@codeaurora.org>
      Reviewed-by: NMarc Zyngier <marc.zyngier@arm.com>
      Signed-off-by: NWill Deacon <will.deacon@arm.com>
      Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
      20a004e7
  3. 09 1月, 2018 1 次提交
  4. 08 1月, 2018 5 次提交
  5. 23 12月, 2017 4 次提交
  6. 21 8月, 2017 1 次提交
  7. 09 4月, 2017 1 次提交
  8. 04 4月, 2017 1 次提交
  9. 21 3月, 2017 3 次提交
  10. 30 1月, 2017 2 次提交
  11. 12 1月, 2017 1 次提交
  12. 05 11月, 2016 1 次提交
    • M
      arm/arm64: KVM: Perform local TLB invalidation when multiplexing vcpus on a single CPU · 94d0e598
      Marc Zyngier 提交于
      Architecturally, TLBs are private to the (physical) CPU they're
      associated with. But when multiple vcpus from the same VM are
      being multiplexed on the same CPU, the TLBs are not private
      to the vcpus (and are actually shared across the VMID).
      
      Let's consider the following scenario:
      
      - vcpu-0 maps PA to VA
      - vcpu-1 maps PA' to VA
      
      If run on the same physical CPU, vcpu-1 can hit TLB entries generated
      by vcpu-0 accesses, and access the wrong physical page.
      
      The solution to this is to keep a per-VM map of which vcpu ran last
      on each given physical CPU, and invalidate local TLBs when switching
      to a different vcpu from the same VM.
      Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
      Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
      94d0e598
  13. 12 9月, 2016 1 次提交
  14. 08 9月, 2016 1 次提交
  15. 04 7月, 2016 8 次提交
  16. 29 6月, 2016 1 次提交
  17. 10 5月, 2016 1 次提交
    • C
      kvm: arm64: Enable hardware updates of the Access Flag for Stage 2 page tables · 06485053
      Catalin Marinas 提交于
      The ARMv8.1 architecture extensions introduce support for hardware
      updates of the access and dirty information in page table entries. With
      VTCR_EL2.HA enabled (bit 21), when the CPU accesses an IPA with the
      PTE_AF bit cleared in the stage 2 page table, instead of raising an
      Access Flag fault to EL2 the CPU sets the actual page table entry bit
      (10). To ensure that kernel modifications to the page table do not
      inadvertently revert a bit set by hardware updates, certain Stage 2
      software pte/pmd operations must be performed atomically.
      
      The main user of the AF bit is the kvm_age_hva() mechanism. The
      kvm_age_hva_handler() function performs a "test and clear young" action
      on the pte/pmd. This needs to be atomic in respect of automatic hardware
      updates of the AF bit. Since the AF bit is in the same position for both
      Stage 1 and Stage 2, the patch reuses the existing
      ptep_test_and_clear_young() functionality if
      __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG is defined. Otherwise, the
      existing pte_young/pte_mkold mechanism is preserved.
      
      The kvm_set_s2pte_readonly() (and the corresponding pmd equivalent) have
      to perform atomic modifications in order to avoid a race with updates of
      the AF bit. The arm64 implementation has been re-written using
      exclusives.
      
      Currently, kvm_set_s2pte_writable() (and pmd equivalent) take a pointer
      argument and modify the pte/pmd in place. However, these functions are
      only used on local variables rather than actual page table entries, so
      it makes more sense to follow the pte_mkwrite() approach for stage 1
      attributes. The change to kvm_s2pte_mkwrite() makes it clear that these
      functions do not modify the actual page table entries.
      
      The (pte|pmd)_mkyoung() uses on Stage 2 entries (setting the AF bit
      explicitly) do not need to be modified since hardware updates of the
      dirty status are not supported by KVM, so there is no possibility of
      losing such information.
      Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
      Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
      Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>
      06485053