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From: Peng Liang <liangpeng10@huawei.com>
To: Andrew Jones <drjones@redhat.com>
Cc: zhang.zhanghailiang@huawei.com, kvm@vger.kernel.org,
	maz@kernel.org, will@kernel.org, kvmarm@lists.cs.columbia.edu
Subject: Re: [RFC v2 6/7] kvm: arm64: make ID registers configurable
Date: Fri, 18 Sep 2020 17:26:37 +0800	[thread overview]
Message-ID: <96d2155f-6ba8-6eee-8eff-354c026232f3@huawei.com> (raw)
In-Reply-To: <20200918075039.36eezfwbsiearq3h@kamzik.brq.redhat.com>

On 9/18/2020 3:50 PM, Andrew Jones wrote:
> On Thu, Sep 17, 2020 at 08:01:00PM +0800, Peng Liang wrote:
>> It's time to make ID registers configurable.  When userspace (but not
>> guest) want to set the values of ID registers, save the value in
>> sysreg file so that guest can read the modified values.
>>
>> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>> Signed-off-by: Peng Liang <liangpeng10@huawei.com>
>> ---
>>  arch/arm64/kvm/sys_regs.c | 16 +++++++++-------
>>  1 file changed, 9 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
>> index a642ecfebe0a..881b66494524 100644
>> --- a/arch/arm64/kvm/sys_regs.c
>> +++ b/arch/arm64/kvm/sys_regs.c
>> @@ -1263,10 +1263,6 @@ static int set_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
>>  
>>  /*
>>   * cpufeature ID register user accessors
>> - *
>> - * For now, these registers are immutable for userspace, so no values
>> - * are stored, and for set_id_reg() we don't allow the effective value
>> - * to be changed.
>>   */
>>  static int __get_id_reg(struct kvm_vcpu *vcpu,
>>  			const struct sys_reg_desc *rd, void __user *uaddr,
>> @@ -1290,9 +1286,15 @@ static int __set_id_reg(struct kvm_vcpu *vcpu,
>>  	if (err)
>>  		return err;
>>  
>> -	/* This is what we mean by invariant: you can't change it. */
>> -	if (val != read_id_reg(vcpu, rd, raz))
>> -		return -EINVAL;
>> +	if (raz) {
>> +		if (val != read_id_reg(vcpu, rd, raz))
> 
> val != 0 ?

Thanks for you advise.  It will make it much clearer.  I'll change it in next
version.

Thanks,
Peng

> 
>> +			return -EINVAL;
>> +	} else {
>> +		u32 reg_id = sys_reg((u32)rd->Op0, (u32)rd->Op1, (u32)rd->CRn,
>> +				     (u32)rd->CRm, (u32)rd->Op2);
>> +		/* val should be checked in check_user */
> 
> It really doesn't make sense to share this trivial set_user function and
> have different check functions. Just don't share the set_user function.
> 
>> +		__vcpu_sys_reg(vcpu, ID_REG_INDEX(reg_id)) = val;
>> +	}
>>  
>>  	return 0;
>>  }
>> -- 
>> 2.26.2
>>
> 
> Thanks,
> drew
> 
> .
>
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WARNING: multiple messages have this Message-ID (diff)
From: Peng Liang <liangpeng10@huawei.com>
To: Andrew Jones <drjones@redhat.com>
Cc: <kvmarm@lists.cs.columbia.edu>, <kvm@vger.kernel.org>,
	<maz@kernel.org>, <will@kernel.org>,
	<zhang.zhanghailiang@huawei.com>, <xiexiangyou@huawei.com>
Subject: Re: [RFC v2 6/7] kvm: arm64: make ID registers configurable
Date: Fri, 18 Sep 2020 17:26:37 +0800	[thread overview]
Message-ID: <96d2155f-6ba8-6eee-8eff-354c026232f3@huawei.com> (raw)
In-Reply-To: <20200918075039.36eezfwbsiearq3h@kamzik.brq.redhat.com>

On 9/18/2020 3:50 PM, Andrew Jones wrote:
> On Thu, Sep 17, 2020 at 08:01:00PM +0800, Peng Liang wrote:
>> It's time to make ID registers configurable.  When userspace (but not
>> guest) want to set the values of ID registers, save the value in
>> sysreg file so that guest can read the modified values.
>>
>> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>> Signed-off-by: Peng Liang <liangpeng10@huawei.com>
>> ---
>>  arch/arm64/kvm/sys_regs.c | 16 +++++++++-------
>>  1 file changed, 9 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
>> index a642ecfebe0a..881b66494524 100644
>> --- a/arch/arm64/kvm/sys_regs.c
>> +++ b/arch/arm64/kvm/sys_regs.c
>> @@ -1263,10 +1263,6 @@ static int set_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
>>  
>>  /*
>>   * cpufeature ID register user accessors
>> - *
>> - * For now, these registers are immutable for userspace, so no values
>> - * are stored, and for set_id_reg() we don't allow the effective value
>> - * to be changed.
>>   */
>>  static int __get_id_reg(struct kvm_vcpu *vcpu,
>>  			const struct sys_reg_desc *rd, void __user *uaddr,
>> @@ -1290,9 +1286,15 @@ static int __set_id_reg(struct kvm_vcpu *vcpu,
>>  	if (err)
>>  		return err;
>>  
>> -	/* This is what we mean by invariant: you can't change it. */
>> -	if (val != read_id_reg(vcpu, rd, raz))
>> -		return -EINVAL;
>> +	if (raz) {
>> +		if (val != read_id_reg(vcpu, rd, raz))
> 
> val != 0 ?

Thanks for you advise.  It will make it much clearer.  I'll change it in next
version.

Thanks,
Peng

> 
>> +			return -EINVAL;
>> +	} else {
>> +		u32 reg_id = sys_reg((u32)rd->Op0, (u32)rd->Op1, (u32)rd->CRn,
>> +				     (u32)rd->CRm, (u32)rd->Op2);
>> +		/* val should be checked in check_user */
> 
> It really doesn't make sense to share this trivial set_user function and
> have different check functions. Just don't share the set_user function.
> 
>> +		__vcpu_sys_reg(vcpu, ID_REG_INDEX(reg_id)) = val;
>> +	}
>>  
>>  	return 0;
>>  }
>> -- 
>> 2.26.2
>>
> 
> Thanks,
> drew
> 
> .
>

  reply	other threads:[~2020-09-18  9:26 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-17 12:00 [RFC v2 0/7] kvm: arm64: emulate ID registers Peng Liang
2020-09-17 12:00 ` Peng Liang
2020-09-17 12:00 ` [RFC v2 1/7] arm64: add a helper function to traverse arm64_ftr_regs Peng Liang
2020-09-17 12:00   ` Peng Liang
2020-09-18  7:18   ` Andrew Jones
2020-09-18  7:18     ` Andrew Jones
2020-09-18  9:24     ` Peng Liang
2020-09-18  9:24       ` Peng Liang
2020-09-18 10:28       ` Andrew Jones
2020-09-18 10:28         ` Andrew Jones
2020-09-18 11:58         ` Peng Liang
2020-09-18 11:58           ` Peng Liang
2020-09-17 12:00 ` [RFC v2 2/7] arm64: introduce check_features Peng Liang
2020-09-17 12:00   ` Peng Liang
2020-09-18  7:30   ` Andrew Jones
2020-09-18  7:30     ` Andrew Jones
2020-09-18  9:25     ` Peng Liang
2020-09-18  9:25       ` Peng Liang
2020-09-17 12:00 ` [RFC v2 3/7] kvm: arm64: save ID registers to sys_regs file Peng Liang
2020-09-17 12:00   ` Peng Liang
2020-09-18  7:34   ` Andrew Jones
2020-09-18  7:34     ` Andrew Jones
2020-09-17 12:00 ` [RFC v2 4/7] kvm: arm64: introduce check_user Peng Liang
2020-09-17 12:00   ` Peng Liang
2020-09-18  7:41   ` Andrew Jones
2020-09-18  7:41     ` Andrew Jones
2020-09-18  9:25     ` Peng Liang
2020-09-18  9:25       ` Peng Liang
2020-09-17 12:00 ` [RFC v2 5/7] kvm: arm64: implement check_user for ID registers Peng Liang
2020-09-17 12:00   ` Peng Liang
2020-09-18  7:46   ` Andrew Jones
2020-09-18  7:46     ` Andrew Jones
2020-09-18  9:26     ` Peng Liang
2020-09-18  9:26       ` Peng Liang
2020-09-17 12:01 ` [RFC v2 6/7] kvm: arm64: make ID registers configurable Peng Liang
2020-09-17 12:01   ` Peng Liang
2020-09-18  7:50   ` Andrew Jones
2020-09-18  7:50     ` Andrew Jones
2020-09-18  9:26     ` Peng Liang [this message]
2020-09-18  9:26       ` Peng Liang
2020-09-17 12:01 ` [RFC v2 7/7] kvm: arm64: add KVM_CAP_ARM_CPU_FEATURE extension Peng Liang
2020-09-17 12:01   ` Peng Liang
2020-09-18  7:55   ` Andrew Jones
2020-09-18  7:55     ` Andrew Jones
2020-09-18  9:26     ` Peng Liang
2020-09-18  9:26       ` Peng Liang
2020-09-18  8:01 ` [RFC v2 0/7] kvm: arm64: emulate ID registers Andrew Jones
2020-09-18  8:01   ` Andrew Jones
2020-09-18  9:51   ` Peng Liang
2020-09-18  9:51     ` Peng Liang
2020-09-18 10:20     ` Andrew Jones
2020-09-18 10:20       ` Andrew Jones

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