linux-kernel - Re: [RFC 5/5] LoongArch: KVM: Enable separate vmid feature

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Message-ID: <f0f1f709-9ae0-3b7e-a074-94538e4c3d89@loongson.cn>
Date: Wed, 4 Dec 2024 11:58:19 +0800
From: bibo mao <maobibo@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: Tianrui Zhao <zhaotianrui@...ngson.cn>, WANG Xuerui <kernel@...0n.name>,
 kvm@...r.kernel.org, loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [RFC 5/5] LoongArch: KVM: Enable separate vmid feature



On 2024/12/3 上午10:48, Huacai Chen wrote:
> Hi, Bibo,
> 
> I think you need to probe LOONGARCH_CPU_GUESTID at the end of
> cpu_probe_common(), otherwise cpu_has_guestid is always false.
yes, it is always false now.
Will negotiate with HW guys and add real probe mechanism.

Regards
Bibo Mao
> 
> Huacai
> 
> On Wed, Nov 13, 2024 at 11:17 AM Bibo Mao <maobibo@...ngson.cn> wrote:
>>
>> With CSR GTLBC shortname for Guest TLB Control Register, separate vmid
>> feature will be enabled if bit 14 CSR_GTLBC_USEVMID is set. Enable
>> this feature if cpu_has_guestid is true when KVM module is loaded.
>>
>> Signed-off-by: Bibo Mao <maobibo@...ngson.cn>
>> ---
>>   arch/loongarch/include/asm/loongarch.h | 2 ++
>>   arch/loongarch/kvm/main.c              | 4 +++-
>>   2 files changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/loongarch/include/asm/loongarch.h b/arch/loongarch/include/asm/loongarch.h
>> index 64ad277e096e..5fee5db3bea0 100644
>> --- a/arch/loongarch/include/asm/loongarch.h
>> +++ b/arch/loongarch/include/asm/loongarch.h
>> @@ -326,6 +326,8 @@
>>   #define  CSR_GTLBC_TGID_WIDTH          8
>>   #define  CSR_GTLBC_TGID_SHIFT_END      (CSR_GTLBC_TGID_SHIFT + CSR_GTLBC_TGID_WIDTH - 1)
>>   #define  CSR_GTLBC_TGID                        (_ULCAST_(0xff) << CSR_GTLBC_TGID_SHIFT)
>> +#define  CSR_GTLBC_USEVMID_SHIFT       14
>> +#define  CSR_GTLBC_USEVMID             (_ULCAST_(0x1) << CSR_GTLBC_USEVMID_SHIFT)
>>   #define  CSR_GTLBC_TOTI_SHIFT          13
>>   #define  CSR_GTLBC_TOTI                        (_ULCAST_(0x1) << CSR_GTLBC_TOTI_SHIFT)
>>   #define  CSR_GTLBC_USETGID_SHIFT       12
>> diff --git a/arch/loongarch/kvm/main.c b/arch/loongarch/kvm/main.c
>> index f89d1df885d7..50c977d8b414 100644
>> --- a/arch/loongarch/kvm/main.c
>> +++ b/arch/loongarch/kvm/main.c
>> @@ -336,7 +336,7 @@ int kvm_arch_enable_virtualization_cpu(void)
>>          write_csr_gcfg(0);
>>          write_csr_gstat(0);
>>          write_csr_gintc(0);
>> -       clear_csr_gtlbc(CSR_GTLBC_USETGID | CSR_GTLBC_TOTI);
>> +       clear_csr_gtlbc(CSR_GTLBC_USETGID | CSR_GTLBC_TOTI | CSR_GTLBC_USEVMID);
>>
>>          /*
>>           * Enable virtualization features granting guest direct control of
>> @@ -359,6 +359,8 @@ int kvm_arch_enable_virtualization_cpu(void)
>>
>>          /* Enable using TGID  */
>>          set_csr_gtlbc(CSR_GTLBC_USETGID);
>> +       if (cpu_has_guestid)
>> +               set_csr_gtlbc(CSR_GTLBC_USEVMID);
>>          kvm_debug("GCFG:%lx GSTAT:%lx GINTC:%lx GTLBC:%lx",
>>                    read_csr_gcfg(), read_csr_gstat(), read_csr_gintc(), read_csr_gtlbc());
>>
>> --
>> 2.39.3
>>