On Fri, 24 Apr 2020 at 14:23, Wanpeng Li <kernellwp@xxxxxxxxx> wrote:
>
> From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
>
> Introduce need_cancel_enter_guest() helper, we need to check some
> conditions before doing CONT_RUN, in addition, it can also catch
> the case vmexit occurred while another event was being delivered
> to guest software since vmx_complete_interrupts() adds the request
> bit.
>
> Tested-by: Haiwei Li <lihaiwei@xxxxxxxxxxx>
> Cc: Haiwei Li <lihaiwei@xxxxxxxxxxx>
> Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> ---
> arch/x86/kvm/vmx/vmx.c | 12 +++++++-----
> arch/x86/kvm/x86.c | 10 ++++++++--
> arch/x86/kvm/x86.h | 1 +
> 3 files changed, 16 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index f1f6638..5c21027 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6577,7 +6577,7 @@ 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)
> {
> - enum exit_fastpath_completion exit_fastpath;
> + enum exit_fastpath_completion exit_fastpath = EXIT_FASTPATH_NONE;
> struct vcpu_vmx *vmx = to_vmx(vcpu);
> unsigned long cr3, cr4;
>
> @@ -6754,10 +6754,12 @@ static enum exit_fastpath_completion vmx_vcpu_run(struct kvm_vcpu *vcpu)
> 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;
> + if (!kvm_need_cancel_enter_guest(vcpu)) {
> + exit_fastpath = vmx_exit_handlers_fastpath(vcpu);
> + /* static call is better with retpolines */
> + if (exit_fastpath == EXIT_FASTPATH_CONT_RUN)
> + goto cont_run;
> + }
The kvm_need_cancel_enter_guest() should not before
vmx_exit_handlers_fastpath() which will break IPI fastpath. How about
applying something like below, otherwise, maybe introduce another
EXIT_FASTPATH_CONT_FAIL to indicate fails due to
kvm_need_cancel_enter_guest() if checking it after
vmx_exit_handlers_fastpath(), then we return 1 in vmx_handle_exit()
directly instead of kvm_skip_emulated_instruction(). VMX-preemption
timer exit doesn't need to skip emulated instruction but wrmsr
TSCDEADLINE MSR exit does which results in a little complex here.
Paolo, what do you think?
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 853d3af..9317924 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6564,6 +6564,9 @@ static enum exit_fastpath_completion
handle_fastpath_preemption_timer(struct kvm
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
+ if (kvm_need_cancel_enter_guest(vcpu))
+ return EXIT_FASTPATH_NONE;
+
if (!vmx->req_immediate_exit &&
!unlikely(vmx->loaded_vmcs->hv_timer_soft_disabled)) {
kvm_lapic_expired_hv_timer(vcpu);
@@ -6771,12 +6774,10 @@ static enum exit_fastpath_completion
vmx_vcpu_run(struct kvm_vcpu *vcpu)
vmx_recover_nmi_blocking(vmx);
vmx_complete_interrupts(vmx);
- if (!(kvm_need_cancel_enter_guest(vcpu))) {
- exit_fastpath = vmx_exit_handlers_fastpath(vcpu);
- if (exit_fastpath == EXIT_FASTPATH_CONT_RUN) {
- vmx_sync_pir_to_irr(vcpu);
- goto cont_run;
- }
+ exit_fastpath = vmx_exit_handlers_fastpath(vcpu);
+ if (exit_fastpath == EXIT_FASTPATH_CONT_RUN) {
+ vmx_sync_pir_to_irr(vcpu);
+ goto cont_run;
}
return exit_fastpath;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 99061ba..11b309c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1618,6 +1618,9 @@ static int
handle_fastpath_set_x2apic_icr_irqoff(struct kvm_vcpu *vcpu, u64 data
static int handle_fastpath_set_tscdeadline(struct kvm_vcpu *vcpu, u64 data)
{
+ if (kvm_need_cancel_enter_guest(vcpu))
+ return 1;
+
if (!kvm_x86_ops.set_hv_timer ||
kvm_mwait_in_guest(vcpu->kvm) ||
kvm_can_post_timer_interrupt(vcpu))
