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This improves KVM world-switch when KVM RISC-V is running as a Guest under some other hypervisor. Signed-off-by: Anup Patel Reviewed-by: Atish Patra --- arch/riscv/include/asm/kvm_nacl.h | 32 +++++++++++++++++++++ arch/riscv/kvm/vcpu.c | 48 ++++++++++++++++++++++++++++--- arch/riscv/kvm/vcpu_switch.S | 29 +++++++++++++++++++ 3 files changed, 105 insertions(+), 4 deletions(-) diff --git a/arch/riscv/include/asm/kvm_nacl.h b/arch/riscv/include/asm/kvm= _nacl.h index a704e8000a58..5e74238ea525 100644 --- a/arch/riscv/include/asm/kvm_nacl.h +++ b/arch/riscv/include/asm/kvm_nacl.h @@ -12,6 +12,8 @@ #include #include =20 +struct kvm_vcpu_arch; + DECLARE_STATIC_KEY_FALSE(kvm_riscv_nacl_available); #define kvm_riscv_nacl_available() \ static_branch_unlikely(&kvm_riscv_nacl_available) @@ -43,6 +45,10 @@ void __kvm_riscv_nacl_hfence(void *shmem, unsigned long page_num, unsigned long page_count); =20 +void __kvm_riscv_nacl_switch_to(struct kvm_vcpu_arch *vcpu_arch, + unsigned long sbi_ext_id, + unsigned long sbi_func_id); + int kvm_riscv_nacl_enable(void); =20 void kvm_riscv_nacl_disable(void); @@ -64,6 +70,32 @@ int kvm_riscv_nacl_init(void); #define nacl_shmem_fast() \ (kvm_riscv_nacl_available() ? nacl_shmem() : NULL) =20 +#define nacl_scratch_read_long(__shmem, __offset) \ +({ \ + unsigned long *__p =3D (__shmem) + \ + SBI_NACL_SHMEM_SCRATCH_OFFSET + \ + (__offset); \ + lelong_to_cpu(*__p); \ +}) + +#define nacl_scratch_write_long(__shmem, __offset, __val) \ +do { \ + unsigned long *__p =3D (__shmem) + \ + SBI_NACL_SHMEM_SCRATCH_OFFSET + \ + (__offset); \ + *__p =3D cpu_to_lelong(__val); \ +} while (0) + +#define nacl_scratch_write_longs(__shmem, __offset, __array, __count) \ +do { \ + unsigned int __i; \ + unsigned long *__p =3D (__shmem) + \ + SBI_NACL_SHMEM_SCRATCH_OFFSET + \ + (__offset); \ + for (__i =3D 0; __i < (__count); __i++) \ + __p[__i] =3D cpu_to_lelong((__array)[__i]); \ +} while (0) + #define nacl_sync_hfence(__e) \ sbi_ecall(SBI_EXT_NACL, SBI_EXT_NACL_SYNC_HFENCE, \ (__e), 0, 0, 0, 0, 0) diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c index 00baaf1b0136..fe849fb1aaab 100644 --- a/arch/riscv/kvm/vcpu.c +++ b/arch/riscv/kvm/vcpu.c @@ -759,19 +759,59 @@ static __always_inline void kvm_riscv_vcpu_swap_in_ho= st_state(struct kvm_vcpu *v */ static void noinstr kvm_riscv_vcpu_enter_exit(struct kvm_vcpu *vcpu) { + void *nsh; struct kvm_cpu_context *gcntx =3D &vcpu->arch.guest_context; struct kvm_cpu_context *hcntx =3D &vcpu->arch.host_context; =20 kvm_riscv_vcpu_swap_in_guest_state(vcpu); guest_state_enter_irqoff(); =20 - hcntx->hstatus =3D ncsr_swap(CSR_HSTATUS, gcntx->hstatus); + if (kvm_riscv_nacl_sync_sret_available()) { + nsh =3D nacl_shmem(); =20 - nsync_csr(-1UL); + if (kvm_riscv_nacl_autoswap_csr_available()) { + hcntx->hstatus =3D + nacl_csr_read(nsh, CSR_HSTATUS); + nacl_scratch_write_long(nsh, + SBI_NACL_SHMEM_AUTOSWAP_OFFSET + + SBI_NACL_SHMEM_AUTOSWAP_HSTATUS, + gcntx->hstatus); + nacl_scratch_write_long(nsh, + SBI_NACL_SHMEM_AUTOSWAP_OFFSET, + SBI_NACL_SHMEM_AUTOSWAP_FLAG_HSTATUS); + } else if (kvm_riscv_nacl_sync_csr_available()) { + hcntx->hstatus =3D nacl_csr_swap(nsh, + CSR_HSTATUS, gcntx->hstatus); + } else { + hcntx->hstatus =3D csr_swap(CSR_HSTATUS, gcntx->hstatus); + } =20 - __kvm_riscv_switch_to(&vcpu->arch); + nacl_scratch_write_longs(nsh, + SBI_NACL_SHMEM_SRET_OFFSET + + SBI_NACL_SHMEM_SRET_X(1), + &gcntx->ra, + SBI_NACL_SHMEM_SRET_X_LAST); + + __kvm_riscv_nacl_switch_to(&vcpu->arch, SBI_EXT_NACL, + SBI_EXT_NACL_SYNC_SRET); + + if (kvm_riscv_nacl_autoswap_csr_available()) { + nacl_scratch_write_long(nsh, + SBI_NACL_SHMEM_AUTOSWAP_OFFSET, + 0); + gcntx->hstatus =3D nacl_scratch_read_long(nsh, + SBI_NACL_SHMEM_AUTOSWAP_OFFSET + + SBI_NACL_SHMEM_AUTOSWAP_HSTATUS); + } else { + gcntx->hstatus =3D csr_swap(CSR_HSTATUS, hcntx->hstatus); + } + } else { + hcntx->hstatus =3D csr_swap(CSR_HSTATUS, gcntx->hstatus); =20 - gcntx->hstatus =3D csr_swap(CSR_HSTATUS, hcntx->hstatus); + __kvm_riscv_switch_to(&vcpu->arch); + + gcntx->hstatus =3D csr_swap(CSR_HSTATUS, hcntx->hstatus); + } =20 vcpu->arch.last_exit_cpu =3D vcpu->cpu; guest_state_exit_irqoff(); diff --git a/arch/riscv/kvm/vcpu_switch.S b/arch/riscv/kvm/vcpu_switch.S index 9f13e5ce6a18..47686bcb21e0 100644 --- a/arch/riscv/kvm/vcpu_switch.S +++ b/arch/riscv/kvm/vcpu_switch.S @@ -218,6 +218,35 @@ SYM_FUNC_START(__kvm_riscv_switch_to) ret SYM_FUNC_END(__kvm_riscv_switch_to) =20 + /* + * Parameters: + * A0 <=3D Pointer to struct kvm_vcpu_arch + * A1 <=3D SBI extension ID + * A2 <=3D SBI function ID + */ +SYM_FUNC_START(__kvm_riscv_nacl_switch_to) + SAVE_HOST_GPRS + + SAVE_HOST_AND_RESTORE_GUEST_CSRS .Lkvm_nacl_switch_return + + /* Resume Guest using SBI nested acceleration */ + add a6, a2, zero + add a7, a1, zero + ecall + + /* Back to Host */ + .align 2 +.Lkvm_nacl_switch_return: + SAVE_GUEST_GPRS + + SAVE_GUEST_AND_RESTORE_HOST_CSRS + + RESTORE_HOST_GPRS + + /* Return to C code */ + ret +SYM_FUNC_END(__kvm_riscv_nacl_switch_to) + SYM_CODE_START(__kvm_riscv_unpriv_trap) /* * We assume that faulting unpriv load/store instruction is --=20 2.34.1