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 <[email protected]>
>> Signed-off-by: Peng Liang <[email protected]>
>> ---
>> 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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