On Fri, Apr 24, 2020 at 02:22:40PM +0800, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
>
> Introduce generic fastpath handler to handle MSR fastpath, VMX-preemption
> timer fastpath etc. In addition, we can't observe benefit from single
> target IPI fastpath when APICv is disabled, let's just enable IPI and
> Timer fastpath when APICv is enabled for now.
There are three different changes being squished into a single patch:
- Refactor code to add helper
- Change !APICv behavior for WRMSR fastpath
- Introduce EXIT_FASTPATH_CONT_RUN
I don't think you necessarily need to break this into three separate
patches, but's the !APICv change needs to be a standalone patch, especially
given the shortlog. E.g. the refactoring could be introduced along with
the second fastpath case, and CONT_RUN could be introduced with its first
usage.
>
> Tested-by: Haiwei Li <lihaiwei@xxxxxxxxxxx>
> Cc: Haiwei Li <lihaiwei@xxxxxxxxxxx>
> Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> ---
> arch/x86/include/asm/kvm_host.h | 1 +
> arch/x86/kvm/vmx/vmx.c | 25 ++++++++++++++++++++-----
> 2 files changed, 21 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index f26df2c..6397723 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -188,6 +188,7 @@ enum {
> enum exit_fastpath_completion {
> EXIT_FASTPATH_NONE,
> EXIT_FASTPATH_SKIP_EMUL_INS,
> + EXIT_FASTPATH_CONT_RUN,
> };
>
> struct x86_emulate_ctxt;
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 766303b..f1f6638 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6559,6 +6559,20 @@ void vmx_update_host_rsp(struct vcpu_vmx *vmx, unsigned long host_rsp)
> }
> }
>
> +static enum exit_fastpath_completion vmx_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
> +{
> + if (!is_guest_mode(vcpu) && vcpu->arch.apicv_active) {
> + switch (to_vmx(vcpu)->exit_reason) {
> + case EXIT_REASON_MSR_WRITE:
> + return handle_fastpath_set_msr_irqoff(vcpu);
> + default:
> + return EXIT_FASTPATH_NONE;
> + }
> + }
> +
> + return EXIT_FASTPATH_NONE;
> +}
> +
> bool __vmx_vcpu_run(struct vcpu_vmx *vmx, unsigned long *regs, bool launched);
>
> static enum exit_fastpath_completion vmx_vcpu_run(struct kvm_vcpu *vcpu)
> @@ -6567,6 +6581,7 @@ static enum exit_fastpath_completion vmx_vcpu_run(struct kvm_vcpu *vcpu)
> struct vcpu_vmx *vmx = to_vmx(vcpu);
> unsigned long cr3, cr4;
>
> +cont_run:
> /* Record the guest's net vcpu time for enforced NMI injections. */
> if (unlikely(!enable_vnmi &&
> vmx->loaded_vmcs->soft_vnmi_blocked))
> @@ -6733,17 +6748,17 @@ static enum exit_fastpath_completion vmx_vcpu_run(struct kvm_vcpu *vcpu)
> if (unlikely(vmx->exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY))
> return EXIT_FASTPATH_NONE;
>
> - if (!is_guest_mode(vcpu) && vmx->exit_reason == EXIT_REASON_MSR_WRITE)
> - exit_fastpath = handle_fastpath_set_msr_irqoff(vcpu);
> - else
> - exit_fastpath = EXIT_FASTPATH_NONE;
> -
> vmx->loaded_vmcs->launched = 1;
> vmx->idt_vectoring_info = vmcs_read32(IDT_VECTORING_INFO_FIELD);
>
> vmx_recover_nmi_blocking(vmx);
> vmx_complete_interrupts(vmx);
>
> + exit_fastpath = vmx_exit_handlers_fastpath(vcpu);
> + /* static call is better with retpolines */
> + if (exit_fastpath == EXIT_FASTPATH_CONT_RUN)
> + goto cont_run;
> +
> return exit_fastpath;
> }
>
> --
> 2.7.4
>
