Re: [PATCH v4 2/6] LoongArch: KVM: Add hypercall instruction emulation support

[maobibo]

On 2024/2/19 上午10:41, Huacai Chen wrote:
> Hi, Bibo,
>
> On Thu, Feb 1, 2024 at 11:19 AM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:
> > On LoongArch system, hypercall instruction is supported when system
> > runs on VM mode. This patch adds dummy function with hypercall
> > instruction emulation, rather than inject EXCCODE_INE invalid
> > instruction exception.
> >
> > Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
> > ---
> >   arch/loongarch/include/asm/Kbuild      |  1 -
> >   arch/loongarch/include/asm/kvm_para.h  | 26 ++++++++++++++++++++++++++
> >   arch/loongarch/include/uapi/asm/Kbuild |  2 --
> >   arch/loongarch/kvm/exit.c              | 10 ++++++++++
> >   4 files changed, 36 insertions(+), 3 deletions(-)
> >   create mode 100644 arch/loongarch/include/asm/kvm_para.h
> >   delete mode 100644 arch/loongarch/include/uapi/asm/Kbuild
> >
> > diff --git a/arch/loongarch/include/asm/Kbuild b/arch/loongarch/include/asm/Kbuild
> > index 93783fa24f6e..22991a6f0e2b 100644
> > --- a/arch/loongarch/include/asm/Kbuild
> > +++ b/arch/loongarch/include/asm/Kbuild
> > @@ -23,4 +23,3 @@ generic-y += poll.h
> >   generic-y += param.h
> >   generic-y += posix_types.h
> >   generic-y += resource.h
> > -generic-y += kvm_para.h
> > diff --git a/arch/loongarch/include/asm/kvm_para.h b/arch/loongarch/include/asm/kvm_para.h
> > new file mode 100644
> > index 000000000000..9425d3b7e486
> > --- /dev/null
> > +++ b/arch/loongarch/include/asm/kvm_para.h
> > @@ -0,0 +1,26 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#ifndef _ASM_LOONGARCH_KVM_PARA_H
> > +#define _ASM_LOONGARCH_KVM_PARA_H
> > +
> > +/*
> > + * LoongArch hypcall return code
> Maybe using "hypercall" in comments is better.
will modify in next patch.

> > + */
> > +#define KVM_HC_STATUS_SUCCESS          0
> > +#define KVM_HC_INVALID_CODE            -1UL
> > +#define KVM_HC_INVALID_PARAMETER       -2UL
> Maybe KVM_HCALL_SUCCESS/KVM_HCALL_INVALID_CODE/KVM_HCALL_PARAMETER is better.
yes, KVM_HCALL_xxxx sounds better. Will modify it.

Regards
Bibo Mao
> Huacai
>
> > +
> > +static inline unsigned int kvm_arch_para_features(void)
> > +{
> > +       return 0;
> > +}
> > +
> > +static inline unsigned int kvm_arch_para_hints(void)
> > +{
> > +       return 0;
> > +}
> > +
> > +static inline bool kvm_check_and_clear_guest_paused(void)
> > +{
> > +       return false;
> > +}
> > +#endif /* _ASM_LOONGARCH_KVM_PARA_H */
> > diff --git a/arch/loongarch/include/uapi/asm/Kbuild b/arch/loongarch/include/uapi/asm/Kbuild
> > deleted file mode 100644
> > index 4aa680ca2e5f..000000000000
> > --- a/arch/loongarch/include/uapi/asm/Kbuild
> > +++ /dev/null
> > @@ -1,2 +0,0 @@
> > -# SPDX-License-Identifier: GPL-2.0
> > -generic-y += kvm_para.h
> > diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
> > index ed1d89d53e2e..d15c71320a11 100644
> > --- a/arch/loongarch/kvm/exit.c
> > +++ b/arch/loongarch/kvm/exit.c
> > @@ -685,6 +685,15 @@ static int kvm_handle_lasx_disabled(struct kvm_vcpu *vcpu)
> >          return RESUME_GUEST;
> >   }
> >
> > +static int kvm_handle_hypcall(struct kvm_vcpu *vcpu)
> > +{
> > +       update_pc(&vcpu->arch);
> > +
> > +       /* Treat it as noop intruction, only set return value */
> > +       vcpu->arch.gprs[LOONGARCH_GPR_A0] = KVM_HC_INVALID_CODE;
> > +       return RESUME_GUEST;
> > +}
> > +
> >   /*
> >    * LoongArch KVM callback handling for unimplemented guest exiting
> >    */
> > @@ -716,6 +725,7 @@ static exit_handle_fn kvm_fault_tables[EXCCODE_INT_START] = {
> >          [EXCCODE_LSXDIS]                = kvm_handle_lsx_disabled,
> >          [EXCCODE_LASXDIS]               = kvm_handle_lasx_disabled,
> >          [EXCCODE_GSPR]                  = kvm_handle_gspr,
> > +       [EXCCODE_HVC]                   = kvm_handle_hypcall,
> >   };
> >
> >   int kvm_handle_fault(struct kvm_vcpu *vcpu, int fault)
> > --
> > 2.39.3