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Message-ID: <f003f38d-37fd-43ed-ada6-fb2d5b282e91@xen0n.name>
Date: Thu, 16 Nov 2023 15:19:23 +0800
From: WANG Xuerui <kernel@...0n.name>
To: Tianrui Zhao <zhaotianrui@...ngson.cn>,
linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Huacai Chen <chenhuacai@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
loongarch@...ts.linux.dev, Jens Axboe <axboe@...nel.dk>,
Mark Brown <broonie@...nel.org>,
Alex Deucher <alexander.deucher@....com>,
Oliver Upton <oliver.upton@...ux.dev>, maobibo@...ngson.cn,
Xi Ruoyao <xry111@...111.site>
Subject: Re: [PATCH v1 2/2] LoongArch: KVM: Add lasx support
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@...ngson.cn>
> ---
> 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.)
--
WANG "xen0n" Xuerui
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