| Message ID | 20191023123119.271229148@linutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | entry: Provide generic implementation for host and guest entry/exit work | expand |
On Wed, Oct 23, 2019 at 02:27:22PM +0200, Thomas Gleixner wrote: > Use the generic infrastructure to check for and handle pending work before > entering into guest mode. > > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > --- > arch/x86/kvm/Kconfig | 1 + > arch/x86/kvm/x86.c | 17 +++++------------ > 2 files changed, 6 insertions(+), 12 deletions(-) > > --- a/arch/x86/kvm/Kconfig > +++ b/arch/x86/kvm/Kconfig > @@ -42,6 +42,7 @@ config KVM > select HAVE_KVM_MSI > select HAVE_KVM_CPU_RELAX_INTERCEPT > select HAVE_KVM_NO_POLL > + select KVM_EXIT_TO_GUEST_WORK > select KVM_GENERIC_DIRTYLOG_READ_PROTECT > select KVM_VFIO > select SRCU > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -52,6 +52,7 @@ > #include <linux/irqbypass.h> > #include <linux/sched/stat.h> > #include <linux/sched/isolation.h> > +#include <linux/entry-common.h> > #include <linux/mem_encrypt.h> > > #include <trace/events/kvm.h> > @@ -8115,8 +8116,8 @@ static int vcpu_enter_guest(struct kvm_v > if (kvm_lapic_enabled(vcpu) && vcpu->arch.apicv_active) > kvm_x86_ops->sync_pir_to_irr(vcpu); > > - if (vcpu->mode == EXITING_GUEST_MODE || kvm_request_pending(vcpu) > - || need_resched() || signal_pending(current)) { > + if (vcpu->mode == EXITING_GUEST_MODE || kvm_request_pending(vcpu) || > + exit_to_guestmode_work_pending()) { The terms EXIT_TO_GUEST and exit_to_guestmode are very confusing, as they're inverted from the usual virt terminology of VM-Enter (enter guest) and VM-Exit (exit guest). The conflict is most obvious here, with the above "vcpu->mode == EXITING_GUEST_MODE", which is checking to see if the vCPU is being forced to exit *from* guest mode because was kicked by some other part of KVM. Maybe XFER_TO_GUEST? I.e. avoid entry/exit entirely, so that neither the entry code or KVM ends up with a confusing name. > vcpu->mode = OUTSIDE_GUEST_MODE; > smp_wmb(); > local_irq_enable(); > @@ -8309,17 +8310,9 @@ static int vcpu_run(struct kvm_vcpu *vcp > > kvm_check_async_pf_completion(vcpu); > > - if (signal_pending(current)) { > - r = -EINTR; > - vcpu->run->exit_reason = KVM_EXIT_INTR; > - ++vcpu->stat.signal_exits; > + r = exit_to_guestmode(kvm, vcpu); Ditto here. If the run loop is stripped down to the core functionality, it effectively looks like: for (;;) { r = vcpu_enter_guest(vcpu); if (r <= 0) break; ... r = exit_to_guestmode(kvm, vcpu); if (r) break; } Appending _handle_work to the function would also be helpful so that it's somewhat clear the function isn't related to the core vcpu_enter_guest() functionality, e.g.: for (;;) { r = vcpu_enter_guest(vcpu); if (r <= 0) break; ... r = xfer_to_guestmode_handle_work(kvm, vcpu); if (r) break; } > + if (r) > break; > - } > - if (need_resched()) { > - srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx); > - cond_resched(); > - vcpu->srcu_idx = srcu_read_lock(&kvm->srcu); > - } > } > > srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx); > >
--- a/arch/x86/kvm/Kconfig +++ b/arch/x86/kvm/Kconfig @@ -42,6 +42,7 @@ config KVM select HAVE_KVM_MSI select HAVE_KVM_CPU_RELAX_INTERCEPT select HAVE_KVM_NO_POLL + select KVM_EXIT_TO_GUEST_WORK select KVM_GENERIC_DIRTYLOG_READ_PROTECT select KVM_VFIO select SRCU --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -52,6 +52,7 @@ #include <linux/irqbypass.h> #include <linux/sched/stat.h> #include <linux/sched/isolation.h> +#include <linux/entry-common.h> #include <linux/mem_encrypt.h> #include <trace/events/kvm.h> @@ -8115,8 +8116,8 @@ static int vcpu_enter_guest(struct kvm_v if (kvm_lapic_enabled(vcpu) && vcpu->arch.apicv_active) kvm_x86_ops->sync_pir_to_irr(vcpu); - if (vcpu->mode == EXITING_GUEST_MODE || kvm_request_pending(vcpu) - || need_resched() || signal_pending(current)) { + if (vcpu->mode == EXITING_GUEST_MODE || kvm_request_pending(vcpu) || + exit_to_guestmode_work_pending()) { vcpu->mode = OUTSIDE_GUEST_MODE; smp_wmb(); local_irq_enable(); @@ -8309,17 +8310,9 @@ static int vcpu_run(struct kvm_vcpu *vcp kvm_check_async_pf_completion(vcpu); - if (signal_pending(current)) { - r = -EINTR; - vcpu->run->exit_reason = KVM_EXIT_INTR; - ++vcpu->stat.signal_exits; + r = exit_to_guestmode(kvm, vcpu); + if (r) break; - } - if (need_resched()) { - srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx); - cond_resched(); - vcpu->srcu_idx = srcu_read_lock(&kvm->srcu); - } } srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
Use the generic infrastructure to check for and handle pending work before entering into guest mode. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- arch/x86/kvm/Kconfig | 1 + arch/x86/kvm/x86.c | 17 +++++------------ 2 files changed, 6 insertions(+), 12 deletions(-)