Re: [PATCH] KVM: Optimize kvm_arch_vcpu_ioctl_run function

Tianjia Zhang
2020-04-15T02:19:29Z

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.

Thanks,
Tianjia

>> ++vcpu->stat.signal_exits;
>> }
>> goto out;
>> }
>>
>> - if (vcpu->run->kvm_valid_regs & ~KVM_SYNC_X86_VALID_FIELDS) {
>> + if (kvm_run->kvm_valid_regs & ~KVM_SYNC_X86_VALID_FIELDS) {
>> r = -EINVAL;
>> goto out;
>> }
>>
>> - if (vcpu->run->kvm_dirty_regs) {
>> + if (kvm_run->kvm_dirty_regs) {
>> r = sync_regs(vcpu);
>> if (r != 0)
>> goto out;
>> @@ -8767,7 +8767,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
>>
>> out:
>> kvm_put_guest_fpu(vcpu);
>> - if (vcpu->run->kvm_valid_regs)
>> + if (kvm_run->kvm_valid_regs)
>> store_regs(vcpu);
>> post_kvm_run_save(vcpu);
>> kvm_sigset_deactivate(vcpu);
>> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
>> index 48d0ec44ad77..ab9d7966a4c8 100644
>> --- a/virt/kvm/arm/arm.c
>> +++ b/virt/kvm/arm/arm.c
>> @@ -659,7 +659,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
>> return ret;
>>
>> if (run->exit_reason == KVM_EXIT_MMIO) {
>> - ret = kvm_handle_mmio_return(vcpu, vcpu->run);
>> + ret = kvm_handle_mmio_return(vcpu, run);
>> if (ret)
>> return ret;
>> }
>