Sean Christopherson ca4efed095 KVM: Fully serialize gfn=>pfn cache refresh via mutex ...

commit 93984f19e7bce4c18084a6ef3dacafb155b806ed upstream.

Protect gfn=>pfn cache refresh with a mutex to fully serialize refreshes.
The refresh logic doesn't protect against

- concurrent unmaps, or refreshes with different GPAs (which may or may not
  happen in practice, for example if a cache is only used under vcpu->mutex;
  but it's allowed in the code)

- a false negative on the memslot generation.  If the first refresh sees
  a stale memslot generation, it will refresh the hva and generation before
  moving on to the hva=>pfn translation.  If it then drops gpc->lock, a
  different user of the cache can come along, acquire gpc->lock, see that
  the memslot generation is fresh, and skip the hva=>pfn update due to the
  userspace address also matching (because it too was updated).

The refresh path can already sleep during hva=>pfn resolution, so wrap
the refresh with a mutex to ensure that any given refresh runs to
completion before other callers can start their refresh.

Cc: stable@vger.kernel.org
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429210025.3293691-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2022-08-17 15:13:43 +02:00

..

kvm

KVM: Fully serialize gfn=>pfn cache refresh via mutex

2022-08-17 15:13:43 +02:00

lib

Revert "irqbypass: do not start cons/prod when failed connect"

2021-05-15 10:26:55 +01:00

Makefile

treewide: Add SPDX license identifier - Makefile/Kconfig

2019-05-21 10:50:46 +02:00