The KVM RISC-V hypervisor might be running as a guest under some other host hypervisor in which case the complete H-extension functionality will be trap-n-emulated by the host hypervisor. In this case, the KVM RISC-V performance can be accelerated using the SBI nested acceleration (NACL) extension if the host hypervisor provides it. These series extends KVM RISC-V to use SBI NACL extension whenever underlying SBI implementation (aka host hypervisor) provides it. These patches can also be found in the riscv_sbi_nested_v2 branch at: https://github.com/avpatel/linux.git To test these patches, run KVM RISC-V as Guest under latest Xvisor found at: https://github.com/xvisor/xvisor.git For the steps to test on Xvisor, refer the Xvisor documentation <xvisor_source>/docs/riscv/riscv64-qemu.txt with two small changes: 1) In step#11, make sure compressed kvm.ko, guest kernel image, and kvmtool are present in the rootfs.img 2) In step#14, make sure AIA is available to Xvisor by using "virt,aia=aplic-imsic" as the QEMU machine name. Changes since v1: - Dropped nacl_shmem_fast() macro from PATCH8 - Added comments in PATCH8 about which back-to-back ncsr_xyz() macros are sub-optimal - Moved nacl_scratch_xyz() macros to PATCH8 Anup Patel (13): RISC-V: KVM: Order the object files alphabetically RISC-V: KVM: Save/restore HSTATUS in C source RISC-V: KVM: Save/restore SCOUNTEREN in C source RISC-V: KVM: Break down the __kvm_riscv_switch_to() into macros RISC-V: KVM: Replace aia_set_hvictl() with aia_hvictl_value() RISC-V: KVM: Don't setup SGEI for zero guest external interrupts RISC-V: Add defines for the SBI nested acceleration extension RISC-V: KVM: Add common nested acceleration support RISC-V: KVM: Use nacl_csr_xyz() for accessing H-extension CSRs RISC-V: KVM: Use nacl_csr_xyz() for accessing AIA CSRs RISC-V: KVM: Use SBI sync SRET call when available RISC-V: KVM: Save trap CSRs in kvm_riscv_vcpu_enter_exit() RISC-V: KVM: Use NACL HFENCEs for KVM request based HFENCEs arch/riscv/include/asm/kvm_nacl.h | 245 ++++++++++++++++++++++++++++++ arch/riscv/include/asm/sbi.h | 120 +++++++++++++++ arch/riscv/kvm/Makefile | 27 ++-- arch/riscv/kvm/aia.c | 114 +++++++++----- arch/riscv/kvm/main.c | 51 ++++++- arch/riscv/kvm/mmu.c | 4 +- arch/riscv/kvm/nacl.c | 152 ++++++++++++++++++ arch/riscv/kvm/tlb.c | 57 ++++--- arch/riscv/kvm/vcpu.c | 184 ++++++++++++++++------ arch/riscv/kvm/vcpu_switch.S | 137 +++++++++++------ arch/riscv/kvm/vcpu_timer.c | 28 ++-- 11 files changed, 941 insertions(+), 178 deletions(-) create mode 100644 arch/riscv/include/asm/kvm_nacl.h create mode 100644 arch/riscv/kvm/nacl.c -- 2.43.0
