Changes since v1:
- Renamed the flags returned by set_spte
- Split up a couple of changes into separate patches and refactored some other
patches
- .set_cr3() handlers never flush TLB rather than taking that as parameter
- Generalized lockless CR3 switching to work acroos different MMU modes
- Implemented lockless CR3/EPTP switching for nested VMX L1<->L2 switches
- Added an LRU cache containing multiple fast-switchable roots instead
of limiting it to only the immediately previous one.
The performance of shadow paging is severely degraded in some workloads
when the guest kernel is using KPTI. This is primarily due to the vastly
increased number of CR3 switches that result from KPTI.
This patch series implements various optimizations to reduce some of this
overhead. Compared to the baseline, this results in a reduction from
~16m12s to ~4m44s for a 4-VCPU kernel compile benchmark and from ~25m5s to
~14m50s for a 1-VCPU kernel compile benchmark.
Junaid Shahid (17):
kvm: x86: Make sync_page() flush remote TLBs once only
kvm: x86: Avoid taking MMU lock in kvm_mmu_sync_roots if no sync is
needed
kvm: x86: Add fast CR3 switch code path
kvm: x86: Introduce kvm_mmu_calc_*_root_page_role()
kvm: x86: Introduce KVM_REQ_LOAD_CR3
kvm: x86: Add support for fast CR3 switch across different MMU modes
kvm: x86: Support resetting the MMU context without resetting roots
kvm: x86: Use fast CR3 switch for nested VMX
kvm: x86: Add ability to skip TLB flush when switching CR3
kvm: x86: Map guest PCIDs to host PCIDs
kvm: vmx: Support INVPCID in shadow paging mode
kvm: x86: Skip TLB flush on fast CR3 switch when indicated by guest
kvm: x86: Add a root_hpa parameter to kvm_mmu->invlpg()
kvm: x86: Support selectively freeing either current or previous MMU
root
kvm: x86: Skip shadow page resync on CR3 switch when indicated by
guest
kvm: x86: Flush only affected TLB entries in kvm_mmu_invlpg*
kvm: x86: Add multi-entry LRU cache for previous CR3s
arch/x86/include/asm/kvm_host.h | 30 ++-
arch/x86/kvm/mmu.c | 447 +++++++++++++++++++++++++++-----
arch/x86/kvm/mmu.h | 33 +++
arch/x86/kvm/paging_tmpl.h | 18 +-
arch/x86/kvm/svm.c | 12 +-
arch/x86/kvm/vmx.c | 155 ++++++++++-
arch/x86/kvm/x86.c | 17 +-
virt/kvm/kvm_main.c | 14 +-
8 files changed, 624 insertions(+), 102 deletions(-)
--
2.18.0.rc1.242.g61856ae69a-goog
