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Subject: Re: [PATCH] LoongArch: KVM: Remove unnecessary CSR register saving
 during enter guest
To: maobibo <maobibo@loongson.cn>, Huacai Chen <chenhuacai@kernel.org>
Cc: kvm@vger.kernel.org, loongarch@lists.linux.dev,
 linux-kernel@vger.kernel.org
References: <20240112035039.833974-1-maobibo@loongson.cn>
 <b7c08e0d-bd7d-aea9-250e-1649e95599b7@loongson.cn>
From: zhaotianrui <zhaotianrui@loongson.cn>
Message-ID: <fbd8b226-1972-322b-d884-bb41d262dd16@loongson.cn>
Date: Thu, 1 Feb 2024 11:29:12 +0800
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Reviewed-by: Tianrui Zhao <zhaotianrui@loongson.cn>

在 2024/1/31 上午11:48, maobibo 写道:
> slightly ping :)
> 
> On 2024/1/12 上午11:50, Bibo Mao wrote:
>> Some CSR registers like CRMD/PRMD are saved during enter VM mode. However
>> they are not restored for actual use, saving for these CSR registers
>> can be removed.
>>
>> Signed-off-by: Bibo Mao <maobibo@loongson.cn>
>> ---
>>   arch/loongarch/kvm/switch.S | 6 ------
>>   1 file changed, 6 deletions(-)
>>
>> diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S
>> index 0ed9040307b7..905b90de50e8 100644
>> --- a/arch/loongarch/kvm/switch.S
>> +++ b/arch/loongarch/kvm/switch.S
>> @@ -213,12 +213,6 @@ SYM_FUNC_START(kvm_enter_guest)
>>       /* Save host GPRs */
>>       kvm_save_host_gpr a2
>> -    /* Save host CRMD, PRMD to stack */
>> -    csrrd    a3, LOONGARCH_CSR_CRMD
>> -    st.d    a3, a2, PT_CRMD
>> -    csrrd    a3, LOONGARCH_CSR_PRMD
>> -    st.d    a3, a2, PT_PRMD
>> -
>>       addi.d    a2, a1, KVM_VCPU_ARCH
>>       st.d    sp, a2, KVM_ARCH_HSP
>>       st.d    tp, a2, KVM_ARCH_HTP
>>
>> base-commit: de927f6c0b07d9e698416c5b287c521b07694cac
>>