[PATCH v2 0/6] KVM/arm64: Cache maintenance relaxations

Marc Zyngier
2018-05-30T12:47:00Z

This small series makes use of features recently introduced in the
ARMv8 architecture to relax the cache maintenance operations on CPUs
that implement these features.

FWB is the most important one. It allows stage-2 to enforce the
cacheability of memory, no matter what the guest says. It also
mandates that the whole machine is cache coherent (no non-coherent
I/O), meaning we can drop a whole class of cache maintenance
operations.

FWB, when combined with CTL_EL0.{IDC,DIC} allows the removal of all
cache maintenance and tracking of pages being executed.

We also take the opportunity to drop a few useless CMOs that were
applied to the HYP page tables, but that were never necessary. This
ended up requiring quite a few changes in out page table accessors so
that they get consistent barriers. These barriers are a bit on the
heavy side, and could be further optimized, although that's probably
for a different patch series

* From v1:
- Reordered the series in a slightly more consistent order
- Added patches refactoring the PT accessors before dropping
the CMOs
- Removed final dsb(ishst) from the last patch, as all PT accessors
now have their own barriers
- Collected Acks from Catalin

Marc Zyngier (6):
arm64: KVM: Add support for Stage-2 control of memory types and
cacheability
arm64: KVM: Handle Set/Way CMOs as NOPs if FWB is present
arm64: KVM: Avoid marking pages as XN in Stage-2 if CTR_EL0.DIC is set
KVM: arm/arm64: Consolidate page-table accessors
KVM: arm/arm64: Stop using {pmd,pud,pgd}_populate
KVM: arm/arm64: Remove unnecessary CMOs when creating HYP page tables

arch/arm/include/asm/kvm_mmu.h | 14 ++-------
arch/arm64/include/asm/cpucaps.h | 3 +-
arch/arm64/include/asm/kvm_arm.h | 1 +
arch/arm64/include/asm/kvm_emulate.h | 2 ++
arch/arm64/include/asm/kvm_mmu.h | 32 +++++++++++++------
arch/arm64/include/asm/memory.h | 7 +++++
arch/arm64/include/asm/pgtable-prot.h | 24 ++++++++++++--
arch/arm64/include/asm/sysreg.h | 1 +
arch/arm64/kernel/cpufeature.c | 20 ++++++++++++
arch/arm64/kvm/sys_regs.c | 8 ++++-
virt/kvm/arm/mmu.c | 45 ++++++++++++++++++++++-----
11 files changed, 125 insertions(+), 32 deletions(-)

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2.17.1