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  1. 05 Sep, 2014 5 commits
  3. 03 Sep, 2014 6 commits
    • Paolo Bonzini's avatar
      KVM: nSVM: propagate the NPF EXITINFO to the guest · 5e352519
      Paolo Bonzini authored 
      This is similar to what the EPT code does with the exit qualification.
This allows the guest to see a valid value for bits 33:32.
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      5e352519
    • Paolo Bonzini's avatar
      KVM: x86: reserve bit 8 of non-leaf PDPEs and PML4Es in 64-bit mode on AMD · a0c0feb5
      Paolo Bonzini authored 
      Bit 8 would be the "global" bit, which does not quite make sense for non-leaf
page table entries.  Intel ignores it; AMD ignores it in PDEs, but reserves it
in PDPEs and PML4Es.  The SVM test is relying on this behavior, so enforce it.
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      a0c0feb5
    • Tiejun Chen's avatar
      KVM: mmio: cleanup kvm_set_mmio_spte_mask · d1431483
      Tiejun Chen authored 
      Just reuse rsvd_bits() inside kvm_set_mmio_spte_mask()
for slightly better code.
Signed-off-by: default avatarTiejun Chen <tiejun.chen@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      d1431483
    • David Matlack's avatar
      kvm: x86: fix stale mmio cache bug · 56f17dd3
      David Matlack authored 
      The following events can lead to an incorrect KVM_EXIT_MMIO bubbling
up to userspace:

(1) Guest accesses gpa X without a memory slot. The gfn is cached in
struct kvm_vcpu_arch (mmio_gfn). On Intel EPT-enabled hosts, KVM sets
the SPTE write-execute-noread so that future accesses cause
EPT_MISCONFIGs.

(2) Host userspace creates a memory slot via KVM_SET_USER_MEMORY_REGION
covering the page just accessed.

(3) Guest attempts to read or write to gpa X again. On Intel, this
generates an EPT_MISCONFIG. The memory slot generation number that
was incremented in (2) would normally take care of this but we fast
path mmio faults through quickly_check_mmio_pf(), which only checks
the per-vcpu mmio cache. Since we hit the cache, KVM passes a
KVM_EXIT_MMIO up to userspace.

This patch fixes the issue by using the memslot generation number
to validate the mmio cache.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarDavid Matlack <dmatlack@google.com>
[xiaoguangrong: adjust the code to make it simpler for stable-tree fix.]
Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Reviewed-by: default avatarDavid Matlack <dmatlack@google.com>
Reviewed-by: default avatarXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Tested-by: default avatarDavid Matlack <dmatlack@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      56f17dd3
    • David Matlack's avatar
      kvm: fix potentially corrupt mmio cache · ee3d1570
      David Matlack authored 
      vcpu exits and memslot mutations can run concurrently as long as the
vcpu does not aquire the slots mutex. Thus it is theoretically possible
for memslots to change underneath a vcpu that is handling an exit.

If we increment the memslot generation number again after
synchronize_srcu_expedited(), vcpus can safely cache memslot generation
without maintaining a single rcu_dereference through an entire vm exit.
And much of the x86/kvm code does not maintain a single rcu_dereference
of the current memslots during each exit.

We can prevent the following case:

   vcpu (CPU 0)                             | thread (CPU 1)
--------------------------------------------+--------------------------
1  vm exit                                  |
2  srcu_read_unlock(&kvm->srcu)             |
3  decide to cache something based on       |
     old memslots                           |
4                                           | change memslots
                                            | (increments generation)
5                                           | synchronize_srcu(&kvm->srcu);
6  retrieve generation # from new memslots  |
7  tag cache with new memslot generation    |
8  srcu_read_unlock(&kvm->srcu)             |
...                                         |
   <action based on cache occurs even       |
    though the caching decision was based   |
    on the old memslots>                    |
...                                         |
   <action *continues* to occur until next  |
    memslot generation change, which may    |
    be never>                               |
                                            |

By incrementing the generation after synchronizing with kvm->srcu readers,
we ensure that the generation retrieved in (6) will become invalid soon
after (8).

Keeping the existing increment is not strictly necessary, but we
do keep it and just move it for consistency from update_memslots to
install_new_memslots.  It invalidates old cached MMIOs immediately,
instead of having to wait for the end of synchronize_srcu_expedited,
which makes the code more clearly correct in case CPU 1 is preempted
right after synchronize_srcu() returns.

To avoid halving the generation space in SPTEs, always presume that the
low bit of the generation is zero when reconstructing a generation number
out of an SPTE.  This effectively disables MMIO caching in SPTEs during
the call to synchronize_srcu_expedited.  Using the low bit this way is
somewhat like a seqcount---where the protected thing is a cache, and
instead of retrying we can simply punt if we observe the low bit to be 1.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarDavid Matlack <dmatlack@google.com>
Reviewed-by: default avatarXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Reviewed-by: default avatarDavid Matlack <dmatlack@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      ee3d1570
    • Paolo Bonzini's avatar
      KVM: do not bias the generation number in kvm_current_mmio_generation · 00f034a1
      Paolo Bonzini authored 
      The next patch will give a meaning (a la seqcount) to the low bit of the
generation number.  Ensure that it matches between kvm->memslots->generation
and kvm_current_mmio_generation().

Cc: stable@vger.kernel.org
Reviewed-by: default avatarDavid Matlack <dmatlack@google.com>
Reviewed-by: default avatarXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      00f034a1
  5. 29 Aug, 2014 13 commits
  7. 26 Aug, 2014 4 commits
    • Paolo Bonzini's avatar
      Merge tag 'kvm-s390-next-20140825' of... · a7428c3d
      Paolo Bonzini authored 
      Merge tag 'kvm-s390-next-20140825' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

KVM: s390: Fixes and features for 3.18 part 1

1. The usual cleanups: get rid of duplicate code, use defines, factor
   out the sync_reg handling, additional docs for sync_regs, better
   error handling on interrupt injection
2. We use KVM_REQ_TLB_FLUSH instead of open coding tlb flushes
3. Additional registers for kvm_run sync regs. This is usually not
   needed in the fast path due to eventfd/irqfd, but kvm stat claims
   that we reduced the overhead of console output by ~50% on my system
4. A rework of the gmap infrastructure. This is the 2nd step towards
   host large page support (after getting rid of the storage key
   dependency). We introduces two radix trees to store the guest-to-host
   and host-to-guest translations. This gets us rid of most of
   the page-table walks in the gmap code. Only one in __gmap_link is left,
   this one is required to link the shadow page table to the process page
   table. Finally this contains the plumbing to support gmap page tables
   with less than 5 levels.
      a7428c3d
    • Martin Schwidefsky's avatar
      KVM: s390/mm: remove outdated gmap data structures · f079e952
      Martin Schwidefsky authored 
      The radix tree rework removed all code that uses the gmap_rmap
and gmap_pgtable data structures. Remove these outdated definitions.
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      f079e952
    • Martin Schwidefsky's avatar
      KVM: s390/mm: support gmap page tables with less than 5 levels · c6c956b8
      Martin Schwidefsky authored 
      Add an addressing limit to the gmap address spaces and only allocate
the page table levels that are needed for the given limit. The limit
is fixed and can not be changed after a gmap has been created.
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      c6c956b8
    • Martin Schwidefsky's avatar
      KVM: s390/mm: use radix trees for guest to host mappings · 527e30b4
      Martin Schwidefsky authored 
      Store the target address for the gmap segments in a radix tree
instead of using invalid segment table entries. gmap_translate
becomes a simple radix_tree_lookup, gmap_fault is split into the
address translation with gmap_translate and the part that does
the linking of the gmap shadow page table with the process page
table.
A second radix tree is used to keep the pointers to the segment
table entries for segments that are mapped in the guest address
space. On unmap of a segment the pointer is retrieved from the
radix tree and is used to carry out the segment invalidation in
the gmap shadow page table. As the radix tree can only store one
pointer, each host segment may only be mapped to exactly one
guest location.
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      527e30b4
  9. 25 Aug, 2014 12 commits
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