Re: [PATCH v1 2/2] LoongArch: KVM: Add lasx support

[zhaotianrui]

在 2023/11/21 下午7:55, Huacai Chen 写道:
> On Tue, Nov 21, 2023 at 5:59 PM zhaotianrui <zhaotianrui@xxxxxxxxxxx> wrote:
> > 在 2023/11/16 下午3:19, WANG Xuerui 写道:
> > > On 11/15/23 17:19, Tianrui Zhao wrote:
> > > > This patch adds LASX support for LoongArch KVM. The LASX means
> > > > LoongArch 256-bits vector instruction.
> > > > There will be LASX exception in KVM when guest use the LASX
> > > > instruction. KVM will enable LASX and restore the vector
> > > > registers for guest then return to guest to continue running.
> > > >
> > > > Signed-off-by: Tianrui Zhao <zhaotianrui@xxxxxxxxxxx>
> > > > ---
> > > >    arch/loongarch/include/asm/kvm_host.h |  6 ++++
> > > >    arch/loongarch/include/asm/kvm_vcpu.h | 10 +++++++
> > > >    arch/loongarch/kernel/fpu.S           |  1 +
> > > >    arch/loongarch/kvm/exit.c             | 18 +++++++++++
> > > >    arch/loongarch/kvm/switch.S           | 16 ++++++++++
> > > >    arch/loongarch/kvm/trace.h            |  4 ++-
> > > >    arch/loongarch/kvm/vcpu.c             | 43 ++++++++++++++++++++++++++-
> > > >    7 files changed, 96 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/arch/loongarch/include/asm/kvm_host.h
> > > > b/arch/loongarch/include/asm/kvm_host.h
> > > > index 6c65c25169..4c05b5eca0 100644
> > > > --- a/arch/loongarch/include/asm/kvm_host.h
> > > > +++ b/arch/loongarch/include/asm/kvm_host.h
> > > > @@ -95,6 +95,7 @@ enum emulation_result {
> > > >    #define KVM_LARCH_SWCSR_LATEST    (0x1 << 1)
> > > >    #define KVM_LARCH_HWCSR_USABLE    (0x1 << 2)
> > > >    #define KVM_LARCH_LSX        (0x1 << 3)
> > > > +#define KVM_LARCH_LASX        (0x1 << 4)
> > > >      struct kvm_vcpu_arch {
> > > >        /*
> > > > @@ -181,6 +182,11 @@ static inline bool kvm_guest_has_lsx(struct
> > > > kvm_vcpu_arch *arch)
> > > >        return arch->cpucfg[2] & CPUCFG2_LSX;
> > > >    }
> > > >    +static inline bool kvm_guest_has_lasx(struct kvm_vcpu_arch *arch)
> > > > +{
> > > > +    return arch->cpucfg[2] & CPUCFG2_LASX;
> > > > +}
> > > > +
> > > >    /* Debug: dump vcpu state */
> > > >    int kvm_arch_vcpu_dump_regs(struct kvm_vcpu *vcpu);
> > > >    diff --git a/arch/loongarch/include/asm/kvm_vcpu.h
> > > > b/arch/loongarch/include/asm/kvm_vcpu.h
> > > > index c629771e12..4f87f16018 100644
> > > > --- a/arch/loongarch/include/asm/kvm_vcpu.h
> > > > +++ b/arch/loongarch/include/asm/kvm_vcpu.h
> > > > @@ -67,6 +67,16 @@ static inline void kvm_restore_lsx(struct
> > > > loongarch_fpu *fpu) { }
> > > >    static inline void kvm_restore_lsx_upper(struct loongarch_fpu *fpu)
> > > > { }
> > > >    #endif
> > > >    +#ifdef CONFIG_CPU_HAS_LASX
> > > > +void kvm_own_lasx(struct kvm_vcpu *vcpu);
> > > > +void kvm_save_lasx(struct loongarch_fpu *fpu);
> > > > +void kvm_restore_lasx(struct loongarch_fpu *fpu);
> > > > +#else
> > > > +static inline void kvm_own_lasx(struct kvm_vcpu *vcpu) { }
> > > > +static inline void kvm_save_lasx(struct loongarch_fpu *fpu) { }
> > > > +static inline void kvm_restore_lasx(struct loongarch_fpu *fpu) { }
> > > > +#endif
> > > > +
> > > >    void kvm_acquire_timer(struct kvm_vcpu *vcpu);
> > > >    void kvm_init_timer(struct kvm_vcpu *vcpu, unsigned long hz);
> > > >    void kvm_reset_timer(struct kvm_vcpu *vcpu);
> > > > diff --git a/arch/loongarch/kernel/fpu.S b/arch/loongarch/kernel/fpu.S
> > > > index d53ab10f46..f4524fe866 100644
> > > > --- a/arch/loongarch/kernel/fpu.S
> > > > +++ b/arch/loongarch/kernel/fpu.S
> > > > @@ -384,6 +384,7 @@ SYM_FUNC_START(_restore_lasx_upper)
> > > >        lasx_restore_all_upper a0 t0 t1
> > > >        jr    ra
> > > >    SYM_FUNC_END(_restore_lasx_upper)
> > > > +EXPORT_SYMBOL(_restore_lasx_upper)
> > > Why the added export? It doesn't seem necessary, given the previous
> > > patch doesn't have a similar export added for _restore_lsx_upper. (Or
> > > if it's truly needed it should probably become EXPORT_SYMBOL_GPL.)
> > It is needed to be exported, as it is called by kvm_own_lasx. However
> > the "_restore_lsx_upper" is not used in kvm.
> To keep consistency it is better to export both.
>
> Huacai
Thanks, I will export both functions.

Tianrui Zhao
> > Thanks
> > Tianrui Zhao