| Message ID | 20220629150625.238286-16-vkuznets@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: VMX: Support TscScaling and EnclsExitingBitmap with eVMCS + use vmcs_config for L1 VMX MSRs | expand |
On Wed, Jun 29, 2022 at 8:07 AM Vitaly Kuznetsov <vkuznets@redhat.com> wrote: > > CPU_BASED_{INTR,NMI}_WINDOW_EXITING controls are toggled dynamically by > vmx_enable_{irq,nmi}_window, handle_interrupt_window(), handle_nmi_window() > but setup_vmcs_config() doesn't check their existence. Add the check and > filter the controls out in vmx_exec_control(). > > No (real) functional change intended as all existing CPUs supporting > VMX are supposed to have these controls. I'm pretty sure vIrtual NMIs and NMI-window exiting are not available on Prescott or Yonah. > Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Jim Mattson <jmattson@google.com>
Jim Mattson <jmattson@google.com> writes: > On Wed, Jun 29, 2022 at 8:07 AM Vitaly Kuznetsov <vkuznets@redhat.com> wrote: >> >> CPU_BASED_{INTR,NMI}_WINDOW_EXITING controls are toggled dynamically by >> vmx_enable_{irq,nmi}_window, handle_interrupt_window(), handle_nmi_window() >> but setup_vmcs_config() doesn't check their existence. Add the check and >> filter the controls out in vmx_exec_control(). >> >> No (real) functional change intended as all existing CPUs supporting >> VMX are supposed to have these controls. > > I'm pretty sure vIrtual NMIs and NMI-window exiting are not available > on Prescott or Yonah. > I seemed to have questioned their existence :-) But you're right, I should've said something like "all CPUs supported by KVM" instead (as pre-patch KVM toggles these controls unconditionally). >> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> > Reviewed-by: Jim Mattson <jmattson@google.com> > Thanks!
On Wed, Jun 29, 2022, Vitaly Kuznetsov wrote: > CPU_BASED_{INTR,NMI}_WINDOW_EXITING controls are toggled dynamically by > vmx_enable_{irq,nmi}_window, handle_interrupt_window(), handle_nmi_window() > but setup_vmcs_config() doesn't check their existence. Add the check and > filter the controls out in vmx_exec_control(). > > No (real) functional change intended as all existing CPUs supporting > VMX are supposed to have these controls. > > Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> > --- > arch/x86/kvm/vmx/vmx.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index da8bbba38d0e..89a3bbafa5af 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -2487,7 +2487,9 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf, > CPU_BASED_MWAIT_EXITING | > CPU_BASED_MONITOR_EXITING | > CPU_BASED_INVLPG_EXITING | > - CPU_BASED_RDPMC_EXITING; > + CPU_BASED_RDPMC_EXITING | > + CPU_BASED_INTR_WINDOW_EXITING | > + CPU_BASED_NMI_WINDOW_EXITING; Requiring NMI_WINDOW_EXITING is wrong, KVM doesn't use NMI_WINDOW_EXITING if enable_vnmi == false: if (!enable_vnmi || vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & GUEST_INTR_STATE_STI) { vmx_enable_irq_window(vcpu); return; } exec_controls_setbit(to_vmx(vcpu), CPU_BASED_NMI_WINDOW_EXITING); And enable_vnmi is cleared if PIN_BASED_VIRTUAL_NMIS are unsupported: if (!cpu_has_virtual_nmis()) enable_vnmi = 0; I suspect CPUs that don't support VIRTUAL_NMIS also don't support NMI_WINDOW_EXITING, and KVM explicitly supports such CPUs. See commit 8a1b43922d0d ("kvm: vmx: Reinstate support for CPUs without virtual NMI"). Making NMI_WINDOW_EXITING optional and then adding it to cpu_has_virtual_nmis() seems like the correct approach. diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h index 069d8d298e1d..c34890e9fc2a 100644 --- a/arch/x86/kvm/vmx/capabilities.h +++ b/arch/x86/kvm/vmx/capabilities.h @@ -82,7 +82,8 @@ static inline bool cpu_has_vmx_basic_inout(void) static inline bool cpu_has_virtual_nmis(void) { - return vmcs_config.pin_based_exec_ctrl & PIN_BASED_VIRTUAL_NMIS; + return vmcs_config.pin_based_exec_ctrl & PIN_BASED_VIRTUAL_NMIS && + vmcs_config.cpu_based_exec_ctrl & CPU_BASED_NMI_WINDOW_EXITING; } static inline bool cpu_has_vmx_preemption_timer(void) > opt = CPU_BASED_TPR_SHADOW | > CPU_BASED_USE_MSR_BITMAPS | > @@ -4300,6 +4302,10 @@ static u32 vmx_exec_control(struct vcpu_vmx *vmx) > { > u32 exec_control = vmcs_config.cpu_based_exec_ctrl; > > + /* INTR_WINDOW_EXITING and NMI_WINDOW_EXITING are toggled dynamically */ > + exec_control &= ~(CPU_BASED_INTR_WINDOW_EXITING | > + CPU_BASED_NMI_WINDOW_EXITING); > + > if (vmx->vcpu.arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT) > exec_control &= ~CPU_BASED_MOV_DR_EXITING; > > -- > 2.35.3 >
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index da8bbba38d0e..89a3bbafa5af 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -2487,7 +2487,9 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf, CPU_BASED_MWAIT_EXITING | CPU_BASED_MONITOR_EXITING | CPU_BASED_INVLPG_EXITING | - CPU_BASED_RDPMC_EXITING; + CPU_BASED_RDPMC_EXITING | + CPU_BASED_INTR_WINDOW_EXITING | + CPU_BASED_NMI_WINDOW_EXITING; opt = CPU_BASED_TPR_SHADOW | CPU_BASED_USE_MSR_BITMAPS | @@ -4300,6 +4302,10 @@ static u32 vmx_exec_control(struct vcpu_vmx *vmx) { u32 exec_control = vmcs_config.cpu_based_exec_ctrl; + /* INTR_WINDOW_EXITING and NMI_WINDOW_EXITING are toggled dynamically */ + exec_control &= ~(CPU_BASED_INTR_WINDOW_EXITING | + CPU_BASED_NMI_WINDOW_EXITING); + if (vmx->vcpu.arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT) exec_control &= ~CPU_BASED_MOV_DR_EXITING;
CPU_BASED_{INTR,NMI}_WINDOW_EXITING controls are toggled dynamically by vmx_enable_{irq,nmi}_window, handle_interrupt_window(), handle_nmi_window() but setup_vmcs_config() doesn't check their existence. Add the check and filter the controls out in vmx_exec_control(). No (real) functional change intended as all existing CPUs supporting VMX are supposed to have these controls. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> --- arch/x86/kvm/vmx/vmx.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)