Re: [PATCH] KVM: Optimize kvm_arch_vcpu_ioctl_run function

Vitaly Kuznetsov
2020-04-15T09:07:53Z

Tianjia Zhang <tianjia.zhang@linux.alibaba.com> writes:

> On 2020/4/14 22:26, Vitaly Kuznetsov wrote:
>> Tianjia Zhang <tianjia.zhang@linux.alibaba.com> writes:
>>
>>> kvm_arch_vcpu_ioctl_run() is only called in the file kvm_main.c,
>>> where vcpu->run is the kvm_run parameter, so it has been replaced.
>>>
>>> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
>>> ---
>>> arch/x86/kvm/x86.c | 8 ++++----
>>> virt/kvm/arm/arm.c | 2 +-
>>> 2 files changed, 5 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>>> index 3bf2ecafd027..70e3f4abbd4d 100644
>>> --- a/arch/x86/kvm/x86.c
>>> +++ b/arch/x86/kvm/x86.c
>>> @@ -8726,18 +8726,18 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
>>> r = -EAGAIN;
>>> if (signal_pending(current)) {
>>> r = -EINTR;
>>> - vcpu->run->exit_reason = KVM_EXIT_INTR;
>>> + kvm_run->exit_reason = KVM_EXIT_INTR;
>>
>> I have a more generic question: why do we need to pass 'kvm_run' to
>> kvm_arch_vcpu_ioctl_run() if it can be extracted from 'struct kvm_vcpu'?
>> The only call site looks like
>>
>> virt/kvm/kvm_main.c: r = kvm_arch_vcpu_ioctl_run(vcpu, vcpu->run);
>>
>
> In the earlier version, kvm_run is used to pass parameters with user
> mode and is not included in the vcpu structure, so it has been retained
> until now.
>

In case this is no longer needed I'd suggest we drop 'kvm_run' parameter
and extract it from 'struct kvm_vcpu' when needed. This looks like a
natural add-on to your cleanup patch.

--
Vitaly