Re: [PATCH] KVM: Optimize kvm_arch_vcpu_ioctl_run function

Vitaly Kuznetsov
2020-04-14T14:26:25Z

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);

> ++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;
> }

--
Vitaly