diff options
| author | Marc Zyngier <maz@kernel.org> | 2023-01-12 15:48:40 +0000 |
|---|---|---|
| committer | Oliver Upton <oliver.upton@linux.dev> | 2023-01-12 21:18:08 +0000 |
| commit | fd2b165ce2ccdaad7d5972987acac259cff66ccb (patch) | |
| tree | 648093d96ab32be7382e719cef6c0755243d4ace | |
| parent | 59d78a2ec0e9cfba5935f3a0d3f14a771461cded (diff) | |
KVM: arm64: vgic-v3: Limit IPI-ing when accessing GICR_{C,S}ACTIVER0
When a vcpu is accessing *its own* redistributor's SGIs/PPIs, there
is no point in doing a stop-the-world operation. Instead, we can
just let the access occur as we do with GICv2.
This is a very minor optimisation for a non-nesting guest, but
a potentially major one for a nesting L1 hypervisor which is
likely to access the emulated registers pretty often (on each
vcpu switch, at the very least).
Reported-by: Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230112154840.1808595-1-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
| -rw-r--r-- | arch/arm64/kvm/vgic/vgic-mmio.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/arch/arm64/kvm/vgic/vgic-mmio.c b/arch/arm64/kvm/vgic/vgic-mmio.c index b32d434c1d4a..e67b3b2c8044 100644 --- a/arch/arm64/kvm/vgic/vgic-mmio.c +++ b/arch/arm64/kvm/vgic/vgic-mmio.c @@ -473,9 +473,10 @@ int vgic_uaccess_write_cpending(struct kvm_vcpu *vcpu, * active state can be overwritten when the VCPU's state is synced coming back * from the guest. * - * For shared interrupts as well as GICv3 private interrupts, we have to - * stop all the VCPUs because interrupts can be migrated while we don't hold - * the IRQ locks and we don't want to be chasing moving targets. + * For shared interrupts as well as GICv3 private interrupts accessed from the + * non-owning CPU, we have to stop all the VCPUs because interrupts can be + * migrated while we don't hold the IRQ locks and we don't want to be chasing + * moving targets. * * For GICv2 private interrupts we don't have to do anything because * userspace accesses to the VGIC state already require all VCPUs to be @@ -484,7 +485,8 @@ int vgic_uaccess_write_cpending(struct kvm_vcpu *vcpu, */ static void vgic_access_active_prepare(struct kvm_vcpu *vcpu, u32 intid) { - if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3 || + if ((vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3 && + vcpu != kvm_get_running_vcpu()) || intid >= VGIC_NR_PRIVATE_IRQS) kvm_arm_halt_guest(vcpu->kvm); } @@ -492,7 +494,8 @@ static void vgic_access_active_prepare(struct kvm_vcpu *vcpu, u32 intid) /* See vgic_access_active_prepare */ static void vgic_access_active_finish(struct kvm_vcpu *vcpu, u32 intid) { - if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3 || + if ((vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3 && + vcpu != kvm_get_running_vcpu()) || intid >= VGIC_NR_PRIVATE_IRQS) kvm_arm_resume_guest(vcpu->kvm); } |