linux-stable.git/arch/x86/kernel/tboot.c, branch linux-rolling-stable

x86/e820: Drop obsolete E820_TYPE_RESERVED_KERN and related code

2025-02-21T15:05:00+00:00

E820_TYPE_RESERVED_KERN is a relict from the ancient history that was used
to early reserve setup_data, see:

  28bb22379513 ("x86: move reserve_setup_data to setup.c")

Nowadays setup_data is anyway reserved in memblock and there is no point in
carrying E820_TYPE_RESERVED_KERN that behaves exactly like E820_TYPE_RAM
but only complicates the code.

A bonus for removing E820_TYPE_RESERVED_KERN is a small but measurable
speedup of 20 microseconds in init_mem_mappings() on a VM with 32GB or RAM.

Signed-off-by: Mike Rapoport (Microsoft) 
Signed-off-by: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: Ard Biesheuvel 
Cc: Kees Cook 
Link: https://lore.kernel.org/r/20250214090651.3331663-5-rppt@kernel.org

mm: remove rb tree.

2022-09-27T02:46:16+00:00

Remove the RB tree and start using the maple tree for vm_area_struct
tracking.

Drop validate_mm() calls in expand_upwards() and expand_downwards() as the
lock is not held.

Link: https://lkml.kernel.org/r/20220906194824.2110408-18-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett 
Tested-by: Yu Zhao 
Cc: Catalin Marinas 
Cc: David Hildenbrand 
Cc: David Howells 
Cc: Davidlohr Bueso 
Cc: "Matthew Wilcox (Oracle)" 
Cc: SeongJae Park 
Cc: Sven Schnelle 
Cc: Vlastimil Babka 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

mm: start tracking VMAs with maple tree

2022-09-27T02:46:14+00:00

Start tracking the VMAs with the new maple tree structure in parallel with
the rb_tree.  Add debug and trace events for maple tree operations and
duplicate the rb_tree that is created on forks into the maple tree.

The maple tree is added to the mm_struct including the mm_init struct,
added support in required mm/mmap functions, added tracking in kernel/fork
for process forking, and used to find the unmapped_area and checked
against what the rbtree finds.

This also moves the mmap_lock() in exit_mmap() since the oom reaper call
does walk the VMAs.  Otherwise lockdep will be unhappy if oom happens.

When splitting a vma fails due to allocations of the maple tree nodes,
the error path in __split_vma() calls new->vm_ops->close(new).  The page
accounting for hugetlb is actually in the close() operation,  so it
accounts for the removal of 1/2 of the VMA which was not adjusted.  This
results in a negative exit value.  To avoid the negative charge, set
vm_start = vm_end and vm_pgoff = 0.

There is also a potential accounting issue in special mappings from
insert_vm_struct() failing to allocate, so reverse the charge there in
the failure scenario.

Link: https://lkml.kernel.org/r/20220906194824.2110408-9-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett 
Signed-off-by: Matthew Wilcox (Oracle) 
Tested-by: Yu Zhao 
Cc: Catalin Marinas 
Cc: David Hildenbrand 
Cc: David Howells 
Cc: Davidlohr Bueso 
Cc: SeongJae Park 
Cc: Sven Schnelle 
Cc: Vlastimil Babka 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

x86/boot/tboot: Move tboot_force_iommu() to Intel IOMMU

2022-07-15T08:21:30+00:00

tboot_force_iommu() is only called by the Intel IOMMU driver. Move the
helper into that driver. No functional change intended.

Signed-off-by: Lu Baolu 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Steve Wahl 
Link: https://lore.kernel.org/r/20220514014322.2927339-7-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel

x86: remove the IOMMU table infrastructure

2022-04-18T05:21:10+00:00

The IOMMU table tries to separate the different IOMMUs into different
backends, but actually requires various cross calls.

Rewrite the code to do the generic swiotlb/swiotlb-xen setup directly
in pci-dma.c and then just call into the IOMMU drivers.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Konrad Rzeszutek Wilk 
Tested-by: Boris Ostrovsky

x86/boot/tboot: Avoid Wstringop-overread-warning

2021-03-22T23:16:13+00:00

gcc-11 warns about using string operations on pointers that are
defined at compile time as offsets from a NULL pointer. Unfortunately
that also happens on the result of fix_to_virt(), which is a
compile-time constant for a constant input:

  arch/x86/kernel/tboot.c: In function 'tboot_probe':
  arch/x86/kernel/tboot.c:70:13: error: '__builtin_memcmp_eq' specified bound 16 exceeds source size 0 [-Werror=stringop-overread]
     70 |         if (memcmp(&tboot_uuid, &tboot->uuid, sizeof(tboot->uuid))) {
        |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I hope this can get addressed in gcc-11 before the release.

As a workaround, split up the tboot_probe() function in two halves
to separate the pointer generation from the usage. This is a bit
ugly, and hopefully gcc understands that the code is actually correct
before it learns to peek into the noinline function.

Signed-off-by: Arnd Bergmann 
Signed-off-by: Ingo Molnar 
Cc: Linus Torvalds 
Cc: Martin Sebor 
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578
Link: https://lore.kernel.org/r/20210322160253.4032422-3-arnd@kernel.org

mm/gup: prevent gup_fast from racing with COW during fork

2020-12-15T20:13:39+00:00

Since commit 70e806e4e645 ("mm: Do early cow for pinned pages during
fork() for ptes") pages under a FOLL_PIN will not be write protected
during COW for fork.  This means that pages returned from
pin_user_pages(FOLL_WRITE) should not become write protected while the pin
is active.

However, there is a small race where get_user_pages_fast(FOLL_PIN) can
establish a FOLL_PIN at the same time copy_present_page() is write
protecting it:

        CPU 0                             CPU 1
   get_user_pages_fast()
    internal_get_user_pages_fast()
                                       copy_page_range()
                                         pte_alloc_map_lock()
                                           copy_present_page()
                                             atomic_read(has_pinned) == 0
					     page_maybe_dma_pinned() == false
     atomic_set(has_pinned, 1);
     gup_pgd_range()
      gup_pte_range()
       pte_t pte = gup_get_pte(ptep)
       pte_access_permitted(pte)
       try_grab_compound_head()
                                             pte = pte_wrprotect(pte)
	                                     set_pte_at();
                                         pte_unmap_unlock()
      // GUP now returns with a write protected page

The first attempt to resolve this by using the write protect caused
problems (and was missing a barrrier), see commit f3c64eda3e50 ("mm: avoid
early COW write protect games during fork()")

Instead wrap copy_p4d_range() with the write side of a seqcount and check
the read side around gup_pgd_range().  If there is a collision then
get_user_pages_fast() fails and falls back to slow GUP.

Slow GUP is safe against this race because copy_page_range() is only
called while holding the exclusive side of the mmap_lock on the src
mm_struct.

[akpm@linux-foundation.org: coding style fixes]
  Link: https://lore.kernel.org/r/CAHk-=wi=iCnYCARbPGjkVJu9eyYeZ13N64tZYLdOB8CP5Q_PLw@mail.gmail.com

Link: https://lkml.kernel.org/r/2-v4-908497cf359a+4782-gup_fork_jgg@nvidia.com
Fixes: f3c64eda3e50 ("mm: avoid early COW write protect games during fork()")
Signed-off-by: Jason Gunthorpe 
Suggested-by: Linus Torvalds 
Reviewed-by: John Hubbard 
Reviewed-by: Jan Kara 
Reviewed-by: Peter Xu 
Acked-by: "Ahmed S. Darwish" 	[seqcount_t parts]
Cc: Andrea Arcangeli 
Cc: "Aneesh Kumar K.V" 
Cc: Christoph Hellwig 
Cc: Hugh Dickins 
Cc: Jann Horn 
Cc: Kirill Shutemov 
Cc: Kirill Tkhai 
Cc: Leon Romanovsky 
Cc: Michal Hocko 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

x86/tboot: Don't disable swiotlb when iommu is forced on

2020-11-25T12:07:32+00:00

After commit 327d5b2fee91c ("iommu/vt-d: Allow 32bit devices to uses DMA
domain"), swiotlb could also be used for direct memory access if IOMMU
is enabled but a device is configured to pass through the DMA translation.
Keep swiotlb when IOMMU is forced on, otherwise, some devices won't work
if "iommu=pt" kernel parameter is used.

Fixes: 327d5b2fee91 ("iommu/vt-d: Allow 32bit devices to uses DMA domain")
Reported-and-tested-by: Adrian Huang 
Signed-off-by: Lu Baolu 
Link: https://lore.kernel.org/r/20201125014124.4070776-1-baolu.lu@linux.intel.com
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=210237
Signed-off-by: Will Deacon

iommu/vt-d: Avoid panic if iommu init fails in tboot system

2020-11-18T13:09:07+00:00

"intel_iommu=off" command line is used to disable iommu but iommu is force
enabled in a tboot system for security reason.

However for better performance on high speed network device, a new option
"intel_iommu=tboot_noforce" is introduced to disable the force on.

By default kernel should panic if iommu init fail in tboot for security
reason, but it's unnecessory if we use "intel_iommu=tboot_noforce,off".

Fix the code setting force_on and move intel_iommu_tboot_noforce
from tboot code to intel iommu code.

Fixes: 7304e8f28bb2 ("iommu/vt-d: Correctly disable Intel IOMMU force on")
Signed-off-by: Zhenzhong Duan 
Tested-by: Lukasz Hawrylko 
Acked-by: Lu Baolu 
Link: https://lore.kernel.org/r/20201110071908.3133-1-zhenzhong.duan@gmail.com
Signed-off-by: Will Deacon

mmap locking API: add MMAP_LOCK_INITIALIZER

2020-06-09T16:39:14+00:00

Define a new initializer for the mmap locking api.  Initially this just
evaluates to __RWSEM_INITIALIZER as the API is defined as wrappers around
rwsem.

Signed-off-by: Michel Lespinasse 
Signed-off-by: Andrew Morton 
Reviewed-by: Laurent Dufour 
Reviewed-by: Vlastimil Babka 
Reviewed-by: Daniel Jordan 
Cc: Davidlohr Bueso 
Cc: David Rientjes 
Cc: Hugh Dickins 
Cc: Jason Gunthorpe 
Cc: Jerome Glisse 
Cc: John Hubbard 
Cc: Liam Howlett 
Cc: Matthew Wilcox 
Cc: Peter Zijlstra 
Cc: Ying Han 
Link: http://lkml.kernel.org/r/20200520052908.204642-9-walken@google.com
Signed-off-by: Linus Torvalds