[PATCH 4/9] KVM: arm/arm64: vgic: Get rid of unnecessary process_maintenance operation
Marc Zyngier
marc.zyngier at arm.com
Tue Mar 21 04:36:19 PDT 2017
On 20/03/17 10:58, Christoffer Dall wrote:
> From: Christoffer Dall <christoffer.dall at linaro.org>
>
> Since we always read back the LRs that we wrote to the guest and the
> MISR and EISR registers simply provide a summary of the configuration of
> the bits in the LRs, there is really no need to read back those status
> registers and process them. We can might as well just signal the
> notifyfd when folding the LR state and save some cycles in the process.
>
> Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
> ---
> virt/kvm/arm/vgic/vgic-v2.c | 55 ++++++++++-----------------------------------
> virt/kvm/arm/vgic/vgic-v3.c | 47 +++++++++++---------------------------
> virt/kvm/arm/vgic/vgic.c | 8 +++----
> virt/kvm/arm/vgic/vgic.h | 4 ++--
> 4 files changed, 31 insertions(+), 83 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-v2.c b/virt/kvm/arm/vgic/vgic-v2.c
> index dfe6e5e..0172754 100644
> --- a/virt/kvm/arm/vgic/vgic-v2.c
> +++ b/virt/kvm/arm/vgic/vgic-v2.c
> @@ -22,20 +22,6 @@
>
> #include "vgic.h"
>
> -/*
> - * Call this function to convert a u64 value to an unsigned long * bitmask
> - * in a way that works on both 32-bit and 64-bit LE and BE platforms.
> - *
> - * Warning: Calling this function may modify *val.
> - */
> -static unsigned long *u64_to_bitmask(u64 *val)
> -{
> -#if defined(CONFIG_CPU_BIG_ENDIAN) && BITS_PER_LONG == 32
> - *val = (*val >> 32) | (*val << 32);
> -#endif
> - return (unsigned long *)val;
> -}
> -
Getting rid of u64_to_bitmask makes me feel slightly better...
> static inline void vgic_v2_write_lr(int lr, u32 val)
> {
> void __iomem *base = kvm_vgic_global_state.vctrl_base;
> @@ -51,38 +37,10 @@ void vgic_v2_init_lrs(void)
> vgic_v2_write_lr(i, 0);
> }
>
> -void vgic_v2_process_maintenance(struct kvm_vcpu *vcpu)
> +void vgic_v2_clear_uie(struct kvm_vcpu *vcpu)
> {
> struct vgic_v2_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v2;
> -
> - if (cpuif->vgic_misr & GICH_MISR_EOI) {
> - u64 eisr = cpuif->vgic_eisr;
> - unsigned long *eisr_bmap = u64_to_bitmask(&eisr);
> - int lr;
> -
> - for_each_set_bit(lr, eisr_bmap, kvm_vgic_global_state.nr_lr) {
> - u32 intid = cpuif->vgic_lr[lr] & GICH_LR_VIRTUALID;
> -
> - WARN_ON(cpuif->vgic_lr[lr] & GICH_LR_STATE);
> -
> - /* Only SPIs require notification */
> - if (vgic_valid_spi(vcpu->kvm, intid))
> - kvm_notify_acked_irq(vcpu->kvm, 0,
> - intid - VGIC_NR_PRIVATE_IRQS);
> - }
> - }
> -
> - /* check and disable underflow maintenance IRQ */
> cpuif->vgic_hcr &= ~GICH_HCR_UIE;
> -
> - /*
> - * In the next iterations of the vcpu loop, if we sync the
> - * vgic state after flushing it, but before entering the guest
> - * (this happens for pending signals and vmid rollovers), then
> - * make sure we don't pick up any old maintenance interrupts
> - * here.
> - */
> - cpuif->vgic_eisr = 0;
> }
>
> void vgic_v2_set_underflow(struct kvm_vcpu *vcpu)
> @@ -92,6 +50,12 @@ void vgic_v2_set_underflow(struct kvm_vcpu *vcpu)
> cpuif->vgic_hcr |= GICH_HCR_UIE;
> }
>
> +static bool lr_signals_eoi_mi(u32 lr_val)
> +{
> + return !(lr_val & GICH_LR_STATE) && (lr_val & GICH_LR_EOI) &&
> + !(lr_val & GICH_LR_HW);
> +}
> +
> /*
> * transfer the content of the LRs back into the corresponding ap_list:
> * - active bit is transferred as is
> @@ -109,6 +73,11 @@ void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu)
> u32 intid = val & GICH_LR_VIRTUALID;
> struct vgic_irq *irq;
>
> + /* Notify fds when the guest EOI'ed a level-triggered SPI */
> + if (lr_signals_eoi_mi(val) && vgic_valid_spi(vcpu->kvm, intid))
> + kvm_notify_acked_irq(vcpu->kvm, 0,
> + intid - VGIC_NR_PRIVATE_IRQS);
> +
> irq = vgic_get_irq(vcpu->kvm, vcpu, intid);
>
> spin_lock(&irq->irq_lock);
> diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
> index 3d7796c..7880c5c 100644
> --- a/virt/kvm/arm/vgic/vgic-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-v3.c
> @@ -21,42 +21,9 @@
>
> #include "vgic.h"
>
> -void vgic_v3_process_maintenance(struct kvm_vcpu *vcpu)
> +void vgic_v3_clear_uie(struct kvm_vcpu *vcpu)
> {
> struct vgic_v3_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v3;
> - u32 model = vcpu->kvm->arch.vgic.vgic_model;
> -
> - if (cpuif->vgic_misr & ICH_MISR_EOI) {
> - unsigned long eisr_bmap = cpuif->vgic_eisr;
> - int lr;
> -
> - for_each_set_bit(lr, &eisr_bmap, kvm_vgic_global_state.nr_lr) {
> - u32 intid;
> - u64 val = cpuif->vgic_lr[lr];
> -
> - if (model == KVM_DEV_TYPE_ARM_VGIC_V3)
> - intid = val & ICH_LR_VIRTUAL_ID_MASK;
> - else
> - intid = val & GICH_LR_VIRTUALID;
> -
> - WARN_ON(cpuif->vgic_lr[lr] & ICH_LR_STATE);
> -
> - /* Only SPIs require notification */
> - if (vgic_valid_spi(vcpu->kvm, intid))
> - kvm_notify_acked_irq(vcpu->kvm, 0,
> - intid - VGIC_NR_PRIVATE_IRQS);
> - }
> -
> - /*
> - * In the next iterations of the vcpu loop, if we sync
> - * the vgic state after flushing it, but before
> - * entering the guest (this happens for pending
> - * signals and vmid rollovers), then make sure we
> - * don't pick up any old maintenance interrupts here.
> - */
> - cpuif->vgic_eisr = 0;
> - }
> -
> cpuif->vgic_hcr &= ~ICH_HCR_UIE;
> }
>
> @@ -67,6 +34,12 @@ void vgic_v3_set_underflow(struct kvm_vcpu *vcpu)
> cpuif->vgic_hcr |= ICH_HCR_UIE;
> }
>
> +static bool lr_signals_eoi_mi(u64 lr_val)
> +{
> + return !(lr_val & ICH_LR_STATE) && (lr_val & ICH_LR_EOI) &&
> + !(lr_val & ICH_LR_HW);
> +}
> +
> void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu)
> {
> struct vgic_v3_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v3;
> @@ -82,6 +55,12 @@ void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu)
> intid = val & ICH_LR_VIRTUAL_ID_MASK;
> else
> intid = val & GICH_LR_VIRTUALID;
> +
> + /* Notify fds when the guest EOI'ed a level-triggered IRQ */
> + if (lr_signals_eoi_mi(val) && vgic_valid_spi(vcpu->kvm, intid))
> + kvm_notify_acked_irq(vcpu->kvm, 0,
> + intid - VGIC_NR_PRIVATE_IRQS);
> +
> irq = vgic_get_irq(vcpu->kvm, vcpu, intid);
> if (!irq) /* An LPI could have been unmapped. */
> continue;
> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
> index 1436c2e..f5b3c25 100644
> --- a/virt/kvm/arm/vgic/vgic.c
> +++ b/virt/kvm/arm/vgic/vgic.c
> @@ -527,12 +527,12 @@ static void vgic_prune_ap_list(struct kvm_vcpu *vcpu)
> spin_unlock(&vgic_cpu->ap_list_lock);
> }
>
> -static inline void vgic_process_maintenance_interrupt(struct kvm_vcpu *vcpu)
> +static inline void vgic_clear_uie(struct kvm_vcpu *vcpu)
> {
> if (kvm_vgic_global_state.type == VGIC_V2)
> - vgic_v2_process_maintenance(vcpu);
> + vgic_v2_clear_uie(vcpu);
> else
> - vgic_v3_process_maintenance(vcpu);
> + vgic_v3_clear_uie(vcpu);
> }
>
> static inline void vgic_fold_lr_state(struct kvm_vcpu *vcpu)
> @@ -642,7 +642,7 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
> if (unlikely(!vgic_initialized(vcpu->kvm)))
> return;
>
> - vgic_process_maintenance_interrupt(vcpu);
> + vgic_clear_uie(vcpu);
> vgic_fold_lr_state(vcpu);
nit: If you moved vgic_*_clear_uie() into vgic_*_fold_lr_state, you
could get rid of this call, extra prototypes, and save yourself the
extra check. Not a big deal though.
> vgic_prune_ap_list(vcpu);
>
> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
> index 3f64220..72ba9ee 100644
> --- a/virt/kvm/arm/vgic/vgic.h
> +++ b/virt/kvm/arm/vgic/vgic.h
> @@ -112,7 +112,7 @@ void vgic_kick_vcpus(struct kvm *kvm);
> int vgic_check_ioaddr(struct kvm *kvm, phys_addr_t *ioaddr,
> phys_addr_t addr, phys_addr_t alignment);
>
> -void vgic_v2_process_maintenance(struct kvm_vcpu *vcpu);
> +void vgic_v2_clear_uie(struct kvm_vcpu *vcpu);
> void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu);
> void vgic_v2_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr);
> void vgic_v2_clear_lr(struct kvm_vcpu *vcpu, int lr);
> @@ -143,7 +143,7 @@ static inline void vgic_get_irq_kref(struct vgic_irq *irq)
> kref_get(&irq->refcount);
> }
>
> -void vgic_v3_process_maintenance(struct kvm_vcpu *vcpu);
> +void vgic_v3_clear_uie(struct kvm_vcpu *vcpu);
> void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu);
> void vgic_v3_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr);
> void vgic_v3_clear_lr(struct kvm_vcpu *vcpu, int lr);
>
Reviewed-by: Marc Zyngier <marc.zyngier at arm.com>
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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