This series redesigns parts of KVM/ARM to optimize the performance on VHE systems. The general approach is to try to do as little work as possible when transitioning between the VM and the hypervisor. This has the benefit of lower latency when waiting for interrupts and delivering virtual interrupts, and reduces the overhead of emulating behavior and I/O in the host kernel. Patches 01 through 06 are not VHE specific, but rework parts of KVM/ARM that can be generally improved. We then add infrastructure to move more logic into vcpu_load and vcpu_put, we improve handling of VFP and debug registers. We then introduce a new world-switch function for VHE systems, which we can tweak and optimize for VHE systems. To do that, we rework a lot of the system register save/restore handling and emulation code that may need access to system registers, so that we can defer as many system register save/restore operations to vcpu_load and vcpu_put, and move this logic out of the VHE world switch function. We then optimize the configuration of traps. On non-VHE systems, both the host and VM kernels run in EL1, but because the host kernel should have full access to the underlying hardware, but the VM kernel should not, we essentially make the host kernel more privileged than the VM kernel despite them both running at the same privilege level by enabling VE traps when entering the VM and disabling those traps when exiting the VM. On VHE systems, the host kernel runs in EL2 and has full access to the hardware (as much as allowed by secure side software), and is unaffected by the trap configuration. That means we can configure the traps for VMs running in EL1 once, and don't have to switch them on and off for every entry/exit to/from the VM. Finally, we improve our VGIC handling by moving all save/restore logic out of the VHE world-switch, and we make it possible to truly only evaluate if the AP list is empty and not do *any* VGIC work if that is the case, and only do the minimal amount of work required in the course of the VGIC processing when we have virtual interrupts in flight. The patches are based on v4.16-rc1 with a fix for userspace irqchips and a patch from Dave Martin that moves CPU ID register traps out of the world switch. I've given the patches a fair amount of testing on Thunder-X, Mustang, Seattle, and TC2 (32-bit) for non-VHE testing, and tested VHE functionality on TX2. The patches are also available in the vhe-optimize-v4 branch on my kernel.org repository [1]. The vhe-optimize-v4-base branch contains prerequisites of this series. Changes since v3: - Rebased on v4.16-rc1 (fun!) - Removed VFP optimizations because it was discovered that the deferred approach taken in v3 was buggy (https://lists.cs.columbia.edu/pipermail/kvmarm/2018-February/029838.html) This causes a fair amount of changes throughout and I've removed affected reviewed-by and other tags as best I could to take this into account. - Used a switch-statement to handle deferred system registers instead of the macro approach taken in v3. - Addressed other review coments (tried to keep track of this with logs of changes in individual patches). - I ran Yury's IPI benchark test and other tests on TX2 and could not observe a performance regression, but rather an improvement of around 65%. I suspect the previous regression was due to the timer WFI problem solved for v4.16-rc1. - I haven't included Tomasz' reviewed-by, because I figured too much of the series has changed since v3. Changes since v2: - Rebased on v4.15-rc3. - Includes two additional patches that only does vcpu_load after kvm_vcpu_first_run_init and only for KVM_RUN. - Addressed review comments from v2 (detailed changelogs are in the individual patches). Thanks, -Christoffer [1]: git://git.kernel.org/pub/scm/linux/kernel/git/cdall/linux.git vhe-optimize-v4 Christoffer Dall (39): KVM: arm/arm64: Avoid vcpu_load for other vcpu ioctls than KVM_RUN KVM: arm/arm64: Move vcpu_load call after kvm_vcpu_first_run_init KVM: arm64: Avoid storing the vcpu pointer on the stack KVM: arm64: Rework hyp_panic for VHE and non-VHE KVM: arm/arm64: Get rid of vcpu->arch.irq_lines KVM: arm/arm64: Add kvm_vcpu_load_sysregs and kvm_vcpu_put_sysregs KVM: arm/arm64: Introduce vcpu_el1_is_32bit KVM: arm64: Move debug dirty flag calculation out of world switch KVM: arm64: Slightly improve debug save/restore functions KVM: arm64: Improve debug register save/restore flow KVM: arm64: Factor out fault info population and gic workarounds KVM: arm64: Introduce VHE-specific kvm_vcpu_run KVM: arm64: Remove kern_hyp_va() use in VHE switch function KVM: arm64: Don't deactivate VM on VHE systems KVM: arm64: Remove noop calls to timer save/restore from VHE switch KVM: arm64: Move userspace system registers into separate function KVM: arm64: Rewrite sysreg alternatives to static keys KVM: arm64: Introduce separate VHE/non-VHE sysreg save/restore functions KVM: arm/arm64: Remove leftover comment from kvm_vcpu_run_vhe KVM: arm64: Unify non-VHE host/guest sysreg save and restore functions KVM: arm64: Don't save the host ELR_EL2 and SPSR_EL2 on VHE systems KVM: arm64: Change 32-bit handling of VM system registers KVM: arm64: Rewrite system register accessors to read/write functions KVM: arm64: Introduce framework for accessing deferred sysregs KVM: arm/arm64: Prepare to handle deferred save/restore of SPSR_EL1 KVM: arm64: Prepare to handle deferred save/restore of ELR_EL1 KVM: arm64: Defer saving/restoring 64-bit sysregs to vcpu load/put on VHE KVM: arm64: Prepare to handle deferred save/restore of 32-bit registers KVM: arm64: Defer saving/restoring 32-bit sysregs to vcpu load/put KVM: arm64: Move common VHE/non-VHE trap config in separate functions KVM: arm64: Directly call VHE and non-VHE FPSIMD enabled functions KVM: arm64: Configure c15, PMU, and debug register traps on cpu load/put for VHE KVM: arm64: Cleanup __activate_traps and __deactive_traps for VHE and non-VHE KVM: arm/arm64: Get rid of vgic_elrsr KVM: arm/arm64: Handle VGICv2 save/restore from the main VGIC code KVM: arm/arm64: Move arm64-only vgic-v2-sr.c file to arm64 KVM: arm/arm64: Handle VGICv3 save/restore from the main VGIC code on VHE KVM: arm/arm64: Move VGIC APR save/restore to vgic put/load KVM: arm/arm64: Avoid VGICv3 save/restore on VHE with no IRQs Shih-Wei Li (1): KVM: arm64: Move HCR_INT_OVERRIDE to default HCR_EL2 guest flag arch/arm/include/asm/kvm_asm.h | 5 +- arch/arm/include/asm/kvm_emulate.h | 21 +- arch/arm/include/asm/kvm_host.h | 6 +- arch/arm/include/asm/kvm_hyp.h | 4 + arch/arm/kvm/emulate.c | 4 +- arch/arm/kvm/hyp/Makefile | 1 - arch/arm/kvm/hyp/switch.c | 16 +- arch/arm64/include/asm/kvm_arm.h | 4 +- arch/arm64/include/asm/kvm_asm.h | 18 +- arch/arm64/include/asm/kvm_emulate.h | 74 +++-- arch/arm64/include/asm/kvm_host.h | 46 ++- arch/arm64/include/asm/kvm_hyp.h | 29 +- arch/arm64/include/asm/kvm_mmu.h | 2 +- arch/arm64/kernel/asm-offsets.c | 1 + arch/arm64/kvm/debug.c | 28 +- arch/arm64/kvm/guest.c | 3 - arch/arm64/kvm/hyp/Makefile | 2 +- arch/arm64/kvm/hyp/debug-sr.c | 88 ++--- arch/arm64/kvm/hyp/entry.S | 6 +- arch/arm64/kvm/hyp/hyp-entry.S | 31 +- arch/arm64/kvm/hyp/switch.c | 373 +++++++++++++--------- arch/arm64/kvm/hyp/sysreg-sr.c | 172 ++++++++-- {virt/kvm/arm => arch/arm64/kvm}/hyp/vgic-v2-sr.c | 81 ----- arch/arm64/kvm/inject_fault.c | 24 +- arch/arm64/kvm/regmap.c | 67 +++- arch/arm64/kvm/sys_regs.c | 166 +++++++--- arch/arm64/kvm/sys_regs.h | 4 +- arch/arm64/kvm/sys_regs_generic_v8.c | 4 +- include/kvm/arm_vgic.h | 2 - virt/kvm/arm/aarch32.c | 2 +- virt/kvm/arm/arch_timer.c | 4 - virt/kvm/arm/arm.c | 50 ++- virt/kvm/arm/hyp/timer-sr.c | 44 +-- virt/kvm/arm/hyp/vgic-v3-sr.c | 244 ++++++++------ virt/kvm/arm/mmu.c | 6 +- virt/kvm/arm/pmu.c | 37 +-- virt/kvm/arm/vgic/vgic-init.c | 11 - virt/kvm/arm/vgic/vgic-v2.c | 61 +++- virt/kvm/arm/vgic/vgic-v3.c | 12 +- virt/kvm/arm/vgic/vgic.c | 21 ++ virt/kvm/arm/vgic/vgic.h | 3 + 41 files changed, 1104 insertions(+), 673 deletions(-) rename {virt/kvm/arm => arch/arm64/kvm}/hyp/vgic-v2-sr.c (51%) -- 2.14.2
