I also tried to port an untested version, but I think your version is a tested one. https://github.com/chenhuacai/linux/commit/e6596b0e45c80756794aba74ac086c5c0e0306eb And I have some questions: 1, "user service" is not only for syscall, so you rename it? 2, Why 4.19 doesn't need something like "vcpu->run->hypercall.args[0] = kvm_read_reg(vcpu, LOONGARCH_GPR_A0);" 3, I think my version about "vcpu->run->exit_reason = KVM_EXIT_HYPERCALL;" and "update_pc()" is a little better than yours, so you can improve them. Huacai On Mon, Dec 23, 2024 at 4:54 PM bibo mao <maobibo@xxxxxxxxxxx> wrote: > > > > On 2024/12/23 下午4:50, Huacai Chen wrote: > > Hi, Bibo, > > > > Is this patch trying to do the same thing as "LoongArch: add hypcall > > to emulate syscall in kvm" in 4.19? > yes, it is to do so -:) > > Regards > Bibo Mao > > > > Huacai > > > > On Mon, Dec 23, 2024 at 4:42 PM Bibo Mao <maobibo@xxxxxxxxxxx> wrote: > >> > >> Some VMMs provides special hypercall service in usermode, KVM need > >> not handle the usermode hypercall service and pass it to VMM and > >> let VMM handle it. > >> > >> Here new code KVM_HCALL_CODE_USER is added for user-mode hypercall > >> service, KVM loads all six registers to VMM. > >> > >> Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx> > >> --- > >> arch/loongarch/include/asm/kvm_host.h | 1 + > >> arch/loongarch/include/asm/kvm_para.h | 2 ++ > >> arch/loongarch/include/uapi/asm/kvm_para.h | 1 + > >> arch/loongarch/kvm/exit.c | 22 ++++++++++++++++++++++ > >> arch/loongarch/kvm/vcpu.c | 3 +++ > >> 5 files changed, 29 insertions(+) > >> > >> diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h > >> index 7b8367c39da8..590982cd986e 100644 > >> --- a/arch/loongarch/include/asm/kvm_host.h > >> +++ b/arch/loongarch/include/asm/kvm_host.h > >> @@ -162,6 +162,7 @@ enum emulation_result { > >> #define LOONGARCH_PV_FEAT_UPDATED BIT_ULL(63) > >> #define LOONGARCH_PV_FEAT_MASK (BIT(KVM_FEATURE_IPI) | \ > >> BIT(KVM_FEATURE_STEAL_TIME) | \ > >> + BIT(KVM_FEATURE_USER_HCALL) | \ > >> BIT(KVM_FEATURE_VIRT_EXTIOI)) > >> > >> struct kvm_vcpu_arch { > >> diff --git a/arch/loongarch/include/asm/kvm_para.h b/arch/loongarch/include/asm/kvm_para.h > >> index c4e84227280d..d3c00de484f6 100644 > >> --- a/arch/loongarch/include/asm/kvm_para.h > >> +++ b/arch/loongarch/include/asm/kvm_para.h > >> @@ -13,12 +13,14 @@ > >> > >> #define KVM_HCALL_CODE_SERVICE 0 > >> #define KVM_HCALL_CODE_SWDBG 1 > >> +#define KVM_HCALL_CODE_USER 2 > >> > >> #define KVM_HCALL_SERVICE HYPERCALL_ENCODE(HYPERVISOR_KVM, KVM_HCALL_CODE_SERVICE) > >> #define KVM_HCALL_FUNC_IPI 1 > >> #define KVM_HCALL_FUNC_NOTIFY 2 > >> > >> #define KVM_HCALL_SWDBG HYPERCALL_ENCODE(HYPERVISOR_KVM, KVM_HCALL_CODE_SWDBG) > >> +#define KVM_HCALL_USER_SERVICE HYPERCALL_ENCODE(HYPERVISOR_KVM, KVM_HCALL_CODE_USER) > >> > >> /* > >> * LoongArch hypercall return code > >> diff --git a/arch/loongarch/include/uapi/asm/kvm_para.h b/arch/loongarch/include/uapi/asm/kvm_para.h > >> index b0604aa9b4bb..76d802ef01ce 100644 > >> --- a/arch/loongarch/include/uapi/asm/kvm_para.h > >> +++ b/arch/loongarch/include/uapi/asm/kvm_para.h > >> @@ -17,5 +17,6 @@ > >> #define KVM_FEATURE_STEAL_TIME 2 > >> /* BIT 24 - 31 are features configurable by user space vmm */ > >> #define KVM_FEATURE_VIRT_EXTIOI 24 > >> +#define KVM_FEATURE_USER_HCALL 25 > >> > >> #endif /* _UAPI_ASM_KVM_PARA_H */ > >> diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c > >> index a7893bd01e73..1a85cd4fb6a5 100644 > >> --- a/arch/loongarch/kvm/exit.c > >> +++ b/arch/loongarch/kvm/exit.c > >> @@ -873,6 +873,28 @@ static int kvm_handle_hypercall(struct kvm_vcpu *vcpu) > >> vcpu->stat.hypercall_exits++; > >> kvm_handle_service(vcpu); > >> break; > >> + case KVM_HCALL_USER_SERVICE: > >> + if (!kvm_guest_has_pv_feature(vcpu, KVM_FEATURE_USER_HCALL)) { > >> + kvm_write_reg(vcpu, LOONGARCH_GPR_A0, KVM_HCALL_INVALID_CODE); > >> + break; > >> + } > >> + > >> + vcpu->run->exit_reason = KVM_EXIT_HYPERCALL; > >> + vcpu->run->hypercall.nr = KVM_HCALL_USER_SERVICE; > >> + vcpu->run->hypercall.args[0] = kvm_read_reg(vcpu, LOONGARCH_GPR_A0); > >> + vcpu->run->hypercall.args[1] = kvm_read_reg(vcpu, LOONGARCH_GPR_A1); > >> + vcpu->run->hypercall.args[2] = kvm_read_reg(vcpu, LOONGARCH_GPR_A2); > >> + vcpu->run->hypercall.args[3] = kvm_read_reg(vcpu, LOONGARCH_GPR_A3); > >> + vcpu->run->hypercall.args[4] = kvm_read_reg(vcpu, LOONGARCH_GPR_A4); > >> + vcpu->run->hypercall.args[5] = kvm_read_reg(vcpu, LOONGARCH_GPR_A5); > >> + vcpu->run->hypercall.flags = 0; > >> + /* > >> + * Set invalid return value by default > >> + * Need user-mode VMM modify it > >> + */ > >> + vcpu->run->hypercall.ret = KVM_HCALL_INVALID_CODE; > >> + ret = RESUME_HOST; > >> + break; > >> case KVM_HCALL_SWDBG: > >> /* KVM_HCALL_SWDBG only in effective when SW_BP is enabled */ > >> if (vcpu->guest_debug & KVM_GUESTDBG_SW_BP_MASK) { > >> diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c > >> index d18a4a270415..8c46ad1872ee 100644 > >> --- a/arch/loongarch/kvm/vcpu.c > >> +++ b/arch/loongarch/kvm/vcpu.c > >> @@ -1735,6 +1735,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu) > >> if (run->exit_reason == KVM_EXIT_LOONGARCH_IOCSR) { > >> if (!run->iocsr_io.is_write) > >> kvm_complete_iocsr_read(vcpu, run); > >> + } else if (run->exit_reason == KVM_EXIT_HYPERCALL) { > >> + kvm_write_reg(vcpu, LOONGARCH_GPR_A0, run->hypercall.ret); > >> + update_pc(&vcpu->arch); > >> } > >> > >> if (!vcpu->wants_to_run) > >> > >> base-commit: 48f506ad0b683d3e7e794efa60c5785c4fdc86fa > >> -- > >> 2.39.3 > >> > >
