[PATCH v2 0/6] KVM: x86/mmu: refine memtype related mmu zap

Yan Zhao
2023-05-09T14:14:31Z

This series refines mmu zap caused by EPT memory type update.

The first 3 patches will only do mmu zap when the target is to update
memory type of EPT entries by introducing a help in patch 1 to skip
non-EPT cases.

The 4th patch will trigger zapping of EPT leaf entries if non-coherent
DMA devices count goes from 0 to 1 or from 1 to 0.

The 5th-6th patches reduces EPT zap count by introducing a per-VM based
guest MTRR and only zap EPT entries when this per-VM based guest MTRR
changes.

Changelog:
v1 --> v2:
1. Added a helper to skip non EPT case in patch 1
2. Added patch 2 to skip mmu zap when guest CR0_CD changes if EPT is not
enabled. (Chao Gao)
3. Added patch 3 to skip mmu zap when guest MTRR changes if EPT is not
enabled.
4. Do not mention TDX in patch 4 as the code is not merged yet (Chao Gao)
5. Added patches 5-6 to reduce EPT zap during guest bootup.

v1:
https://lore.kernel.org/all/20230508034700.7686-1-yan.y.zhao@intel.com/

Yan Zhao (6):
KVM: x86/mmu: add a new mmu zap helper to indicate memtype changes
KVM: x86/mmu: only zap EPT when guest CR0_CD changes
KVM: x86/mmu: only zap EPT when guest MTRR changes
KVM: x86/mmu: Zap all EPT leaf entries according noncoherent DMA count
KVM: x86: Keep a per-VM MTRR state
KVM: x86/mmu: use per-VM based MTRR for EPT

arch/x86/include/asm/kvm_host.h | 3 +
arch/x86/kvm/mmu.h | 1 +
arch/x86/kvm/mmu/mmu.c | 18 ++++-
arch/x86/kvm/mtrr.c | 112 +++++++++++++++++++++++++-------
arch/x86/kvm/vmx/vmx.c | 2 +-
arch/x86/kvm/x86.c | 10 ++-
arch/x86/kvm/x86.h | 6 +-
7 files changed, 122 insertions(+), 30 deletions(-)

base-commit: 5c291b93e5d665380dbecc6944973583f9565ee5
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2.17.1