This patch series combines the previous armv7 and armv8 versions. For an FP and lmbench load it reduces fp/simd context switch from 30-50% down to near 0%. Results will vary with load but is no worse then current approach. In summary current lazy vfp/simd implementation switches hardware context only on guest access and again on exit to host, otherwise hardware context is skipped. This patch set builds on that functionality and executes a hardware context switch only when vCPU is scheduled out or returns to user space. Running floating point app on nearly idle system: ./tst-float 100000uS - (sleep for .1s) fp/simd switch reduced by 99%+ ./tst-float 10000uS - (sleep for .01s) reduced by 98%+ ./tst-float 1000uS - (sleep for 1ms) reduced by ~98% ... ./tst-float 1uS - reduced by 2%+ Tested on FastModels and Foundation Model (need to test on Juno) Tests Ran: ---------- armv7 - with CONFIG_VFP, CONFIG_NEON, CONFIG_KERNEL_MODE_NEON options enabled: - On host executed 12 fp applications - evenly pinned to cpus - Two guests - with 12 fp processes - also pinned to vpus. - Executing with various sleep intervals to measure ration between exits and fp/simd switch armv8: - added mix of armv7 and armv8 guests. These patches are based on earlier arm64 fp/simd optimization work - https://lists.cs.columbia.edu/pipermail/kvmarm/2015-July/015748.html And subsequent fixes by Marc and Christoffer at KVM Forum hackathon to handle 32-bit guest on 64 bit host - https://lists.cs.columbia.edu/pipermail/kvmarm/2015-August/016128.html Chances since v4->v5: - Followed up on Marcs comments - Removed dirty flag, and used trap bits to check for dirty fp/simd - Seperated host form hyp code - As a consequence for arm64 added a commend assember header file - Fixed up critical accesses to fpexec, and added isb - Converted defines to inline functions Changes since v3->v4: - Followup on Christoffers comments - Move fpexc handling to vcpu_load and vcpu_put - Enable and restore fpexc in EL2 mode when running a 32 bit guest on 64bit EL2 - rework hcptr handling Changes since v2->v3: - combined arm v7 and v8 into one short patch series - moved access to fpexec_el2 back to EL2 - Move host restore to EL1 from EL2 and call directly from host - optimize trap enable code - renamed some variables to match usage Changes since v1->v2: - Fixed vfp/simd trap configuration to enable trace trapping - Removed set_hcptr branch label - Fixed handling of FPEXC to restore guest and host versions on vcpu_put - Tested arm32/arm64 - rebased to 4.3-rc2 - changed a couple register accesses from 64 to 32 bit Mario Smarduch (3): add hooks for armv7 fp/simd lazy switch support enable enhanced armv7 fp/simd lazy switch enable enhanced armv8 fp/simd lazy switch arch/arm/include/asm/kvm_emulate.h | 55 ++++++++++++++++++ arch/arm/include/asm/kvm_host.h | 9 +++ arch/arm/kernel/asm-offsets.c | 2 + arch/arm/kvm/Makefile | 2 +- arch/arm/kvm/arm.c | 25 ++++++++ arch/arm/kvm/fpsimd_switch.S | 46 +++++++++++++++ arch/arm/kvm/interrupts.S | 32 +++-------- arch/arm/kvm/interrupts_head.S | 33 +++++------ arch/arm64/include/asm/kvm_asm.h | 2 + arch/arm64/include/asm/kvm_emulate.h | 16 ++++++ arch/arm64/include/asm/kvm_host.h | 15 +++++ arch/arm64/kernel/asm-offsets.c | 1 + arch/arm64/kvm/Makefile | 3 +- arch/arm64/kvm/fpsimd_switch.S | 38 ++++++++++++ arch/arm64/kvm/hyp.S | 108 +++++++++++++---------------------- arch/arm64/kvm/hyp_head.S | 48 ++++++++++++++++ 16 files changed, 322 insertions(+), 113 deletions(-) create mode 100644 arch/arm/kvm/fpsimd_switch.S create mode 100644 arch/arm64/kvm/fpsimd_switch.S create mode 100644 arch/arm64/kvm/hyp_head.S -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
