9 Commits

Author SHA1 Message Date
Ben Gardon
29cf0f5007 kvm: x86/mmu: NX largepage recovery for TDP MMU
When KVM maps a largepage backed region at a lower level in order to
make it executable (i.e. NX large page shattering), it reduces the TLB
performance of that region. In order to avoid making this degradation
permanent, KVM must periodically reclaim shattered NX largepages by
zapping them and allowing them to be rebuilt in the page fault handler.

With this patch, the TDP MMU does not respect KVM's rate limiting on
reclaim. It traverses the entire TDP structure every time. This will be
addressed in a future patch.

Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell
machine. This series introduced no new failures.

This series can be viewed in Gerrit at:
	https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538

Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20201014182700.2888246-21-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-10-23 03:42:16 -04:00
Ben Gardon
bb18842e21 kvm: x86/mmu: Add TDP MMU PF handler
Add functions to handle page faults in the TDP MMU. These page faults
are currently handled in much the same way as the x86 shadow paging
based MMU, however the ordering of some operations is slightly
different. Future patches will add eager NX splitting, a fast page fault
handler, and parallel page faults.

Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell
machine. This series introduced no new failures.

This series can be viewed in Gerrit at:
	https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538

Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20201014182700.2888246-11-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-10-23 03:42:04 -04:00
Ben Gardon
2f2fad0897 kvm: x86/mmu: Add functions to handle changed TDP SPTEs
The existing bookkeeping done by KVM when a PTE is changed is spread
around several functions. This makes it difficult to remember all the
stats, bitmaps, and other subsystems that need to be updated whenever a
PTE is modified. When a non-leaf PTE is marked non-present or becomes a
leaf PTE, page table memory must also be freed. To simplify the MMU and
facilitate the use of atomic operations on SPTEs in future patches, create
functions to handle some of the bookkeeping required as a result of
a change.

Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell
machine. This series introduced no new failures.

This series can be viewed in Gerrit at:
	https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538

Signed-off-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-10-21 18:17:01 -04:00
Ben Gardon
02c00b3a2f kvm: x86/mmu: Allocate and free TDP MMU roots
The TDP MMU must be able to allocate paging structure root pages and track
the usage of those pages. Implement a similar, but separate system for root
page allocation to that of the x86 shadow paging implementation. When
future patches add synchronization model changes to allow for parallel
page faults, these pages will need to be handled differently from the
x86 shadow paging based MMU's root pages.

Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell
machine. This series introduced no new failures.

This series can be viewed in Gerrit at:
	https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538

Signed-off-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-10-21 18:17:00 -04:00
Paolo Bonzini
5a9624affe KVM: mmu: extract spte.h and spte.c
The SPTE format will be common to both the shadow and the TDP MMU.

Extract code that implements the format to a separate module, as a
first step towards adding the TDP MMU and putting mmu.c on a diet.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-10-21 18:16:59 -04:00
Sean Christopherson
e47c4aee5b KVM: x86/mmu: Rename page_header() to to_shadow_page()
Rename KVM's accessor for retrieving a 'struct kvm_mmu_page' from the
associated host physical address to better convey what the function is
doing.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200622202034.15093-7-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-07-08 16:21:55 -04:00
Sean Christopherson
573546820b KVM: x86/mmu: Add sptep_to_sp() helper to wrap shadow page lookup
Introduce sptep_to_sp() to reduce the boilerplate code needed to get the
shadow page associated with a spte pointer, and to improve readability
as it's not immediately obvious that "page_header" is a KVM-specific
accessor for retrieving a shadow page.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200622202034.15093-6-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-07-08 16:21:55 -04:00
Sean Christopherson
985ab27801 KVM: x86/mmu: Make kvm_mmu_page definition and accessor internal-only
Make 'struct kvm_mmu_page' MMU-only, nothing outside of the MMU should
be poking into the gory details of shadow pages.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200622202034.15093-5-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-07-08 16:21:54 -04:00
Sean Christopherson
6ca9a6f3ad KVM: x86/mmu: Add MMU-internal header
Add mmu/mmu_internal.h to hold declarations and definitions that need
to be shared between various mmu/ files, but should not be used by
anything outside of the MMU.

Begin populating mmu_internal.h with declarations of the helpers used by
page_track.c.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200622202034.15093-4-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-07-08 16:21:54 -04:00