On Mon, Dec 30, 2024 at 10:13 AM bibo mao <maobibo@xxxxxxxxxxx> wrote: > > Hi Huacai, > > On 2024/12/23 下午5:05, Huacai Chen wrote: > > 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. > After a second thought, update_pc() before return to user may be not > strictly right, since user VMM can dump registers including pc which is > advanced already. Agree, and we can see how others do. > > How about adding function kvm_complete_hypercall() like > kvm_complete_mmio_read(), such as: kvm_complete_user_service() maybe better? Since the "classic hypercall" doesn't come here. And we may also need to set vcpu->run->exit_reason for all cases, which is done in my version. Huacai > --- a/arch/loongarch/kvm/exit.c > +++ b/arch/loongarch/kvm/exit.c > +int kvm_complete_hypercall(struct kvm_vcpu *vcpu, struct kvm_run *run) > +{ > + update_pc(&vcpu->arch); > + kvm_write_reg(vcpu, LOONGARCH_GPR_A0, run->hypercall.ret); > +} > + > --- a/arch/loongarch/kvm/vcpu.c > +++ b/arch/loongarch/kvm/vcpu.c > @@ -1736,8 +1736,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu) > 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); > + kvm_complete_hypercall(vcpu, run); > + run->exit_reason = KVM_EXIT_UNKNOWN; > } > > Regards > Bibo Mao > > > > 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 > >>>> > >> > >> >
