[PATCH v2 00/10] KVM: arm/arm64: vgic: Improvements and optimizations

[PATCH v2 00/10] KVM: arm/arm64: vgic: Improvements and optimizations

[Christoffer Dall]

We can improve the performance of our VGIC implementation a bit and
clean up a lot of the implementation while we're at it.

At first, patch 1 may seem excessive for a single register, the VMCR,
but while it adds complexity it does move logic out of the critical path
and into the vcpu_load/put hooks, which are executed much more rarely.
It also provides an infrastructure to move more things into the
vgic_load/put functions later one.

Avoiding the need to take a spinlock in the common case where there are
no virtual interrupts in flight are actually measurable and well worth
the effort.

The implementation cleanups boil down to maintaining a single count of
the used LRs instead of an additional bitmap, avoiding the need to deal
with the MISR and EISR fields, and doing an early init of the VGIC to
avoid a number of vgic_initialized() checks.

Tested on Mustang and TC2, and Thunder-X.

Changelogs are in the patches.

Patches also available on:
git://git.kernel.org/pub/scm/linux/kernel/git/cdall/linux.git gic-optimize-v2

Thanks,
-Christoffer

Christoffer Dall (9):
  KVM: arm/arm64: vgic: Defer touching GICH_VMCR to vcpu_load/put
  KVM: arm/arm64: vgic: Get rid of live_lrs
  KVM: arm/arm64: vgic: Only set underflow when actually out of LRs
  KVM: arm/arm64: vgic: Get rid of unnecessary process_maintenance
    operation
  KVM: arm/arm64: vgic: Get rid of unnecessary save_maint_int_state
  KVM: arm/arm64: vgic: Get rid of MISR and EISR fields
  KVM: arm/arm64: vgic: Implement early VGIC init functionality
  KVM: arm/arm64: vgic: Don't check vgic_initialized in sync/flush
  KVM: arm/arm64: vgic: Improve sync_hwstate performance

Shih-Wei Li (1):
  KVM: arm/arm64: vgic: Avoid flushing vgic state when there's no
    pending IRQ

 arch/arm/include/asm/kvm_asm.h   |   3 ++
 arch/arm/kvm/arm.c               |  11 ++--
 arch/arm64/include/asm/kvm_asm.h |   2 +
 include/kvm/arm_vgic.h           |   9 ++--
 virt/kvm/arm/hyp/vgic-v2-sr.c    |  78 +++-------------------------
 virt/kvm/arm/hyp/vgic-v3-sr.c    |  79 +++++++---------------------
 virt/kvm/arm/vgic/vgic-init.c    | 108 ++++++++++++++++++++++++---------------
 virt/kvm/arm/vgic/vgic-v2.c      |  90 ++++++++++++++------------------
 virt/kvm/arm/vgic/vgic-v3.c      |  80 ++++++++++++++---------------
 virt/kvm/arm/vgic/vgic.c         |  60 ++++++++++++++++------
 virt/kvm/arm/vgic/vgic.h         |   8 ++-
 11 files changed, 234 insertions(+), 294 deletions(-)

-- 
2.9.0

[PATCH v2 01/10] KVM: arm/arm64: vgic: Defer touching GICH_VMCR to vcpu_load/put

[Christoffer Dall]

From: Christoffer Dall <cdall@cs.columbia.edu>

We don't have to save/restore the VMCR on every entry to/from the guest,
since on GICv2 we can access the control interface from EL1 and on VHE
systems with GICv3 we can access the control interface from KVM running
in EL2.

GICv3 systems without VHE become the rare case, which have to
save/restore the register in the put/load functions by doing an extra
jump to EL2 to access the EL2-only register state.

Note that userspace accesses may see out-of-date values if the VCPU is
running while accessing the VGIC state via the KVM device API, but this
is already the case and it is up to userspace to quiesce the CPUs before
reading the CPU registers from the GIC for an up-to-date view.

Signed-off-by: Christoffer Dall <cdall@cs.columbia.edu>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
---
Changes since v1:
 - Removed checking for in-context accesses in the uaccess handlers.
 arch/arm/include/asm/kvm_asm.h   |  3 +++
 arch/arm/kvm/arm.c               | 11 ++++++-----
 arch/arm64/include/asm/kvm_asm.h |  2 ++
 include/kvm/arm_vgic.h           |  3 +++
 virt/kvm/arm/hyp/vgic-v2-sr.c    |  3 ---
 virt/kvm/arm/hyp/vgic-v3-sr.c    | 14 ++++++++++----
 virt/kvm/arm/vgic/vgic-init.c    | 12 ++++++++++++
 virt/kvm/arm/vgic/vgic-v2.c      | 24 ++++++++++++++++++++++--
 virt/kvm/arm/vgic/vgic-v3.c      | 22 ++++++++++++++++++++--
 virt/kvm/arm/vgic/vgic.c         | 22 ++++++++++++++++++++++
 virt/kvm/arm/vgic/vgic.h         |  6 ++++++
 11 files changed, 106 insertions(+), 16 deletions(-)

diff --git a/arch/arm/include/asm/kvm_asm.h b/arch/arm/include/asm/kvm_asm.h
index 8ef0538..dd16044 100644
--- a/arch/arm/include/asm/kvm_asm.h
+++ b/arch/arm/include/asm/kvm_asm.h
@@ -75,7 +75,10 @@ extern void __init_stage2_translation(void);
 extern void __kvm_hyp_reset(unsigned long);
 
 extern u64 __vgic_v3_get_ich_vtr_el2(void);
+extern u64 __vgic_v3_read_vmcr(void);
+extern void __vgic_v3_write_vmcr(u32 vmcr);
 extern void __vgic_v3_init_lrs(void);
+
 #endif
 
 #endif /* __ARM_KVM_ASM_H__ */
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index d775aac..cfdf2f5 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -348,15 +348,14 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	vcpu->arch.host_cpu_context = this_cpu_ptr(kvm_host_cpu_state);
 
 	kvm_arm_set_running_vcpu(vcpu);
+
+	kvm_vgic_load(vcpu);
 }
 
 void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 {
-	/*
-	 * The arch-generic KVM code expects the cpu field of a vcpu to be -1
-	 * if the vcpu is no longer assigned to a cpu.  This is used for the
-	 * optimized make_all_cpus_request path.
-	 */
+	kvm_vgic_put(vcpu);
+
 	vcpu->cpu = -1;
 
 	kvm_arm_set_running_vcpu(NULL);
@@ -630,7 +629,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		 * non-preemptible context.
 		 */
 		preempt_disable();
+
 		kvm_pmu_flush_hwstate(vcpu);
+
 		kvm_timer_flush_hwstate(vcpu);
 		kvm_vgic_flush_hwstate(vcpu);
 
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index ec3553eb..49f99cd 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -59,6 +59,8 @@ extern void __kvm_tlb_flush_local_vmid(struct kvm_vcpu *vcpu);
 extern int __kvm_vcpu_run(struct kvm_vcpu *vcpu);
 
 extern u64 __vgic_v3_get_ich_vtr_el2(void);
+extern u64 __vgic_v3_read_vmcr(void);
+extern void __vgic_v3_write_vmcr(u32 vmcr);
 extern void __vgic_v3_init_lrs(void);
 
 extern u32 __kvm_get_mdcr_el2(void);
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index c0b3d99..8d7c3a7 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -307,6 +307,9 @@ bool kvm_vgic_map_is_active(struct kvm_vcpu *vcpu, unsigned int virt_irq);
 
 int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu);
 
+void kvm_vgic_load(struct kvm_vcpu *vcpu);
+void kvm_vgic_put(struct kvm_vcpu *vcpu);
+
 #define irqchip_in_kernel(k)	(!!((k)->arch.vgic.in_kernel))
 #define vgic_initialized(k)	((k)->arch.vgic.initialized)
 #define vgic_ready(k)		((k)->arch.vgic.ready)
diff --git a/virt/kvm/arm/hyp/vgic-v2-sr.c b/virt/kvm/arm/hyp/vgic-v2-sr.c
index c8aeb7b..d3d3b9b 100644
--- a/virt/kvm/arm/hyp/vgic-v2-sr.c
+++ b/virt/kvm/arm/hyp/vgic-v2-sr.c
@@ -114,8 +114,6 @@ void __hyp_text __vgic_v2_save_state(struct kvm_vcpu *vcpu)
 	if (!base)
 		return;
 
-	cpu_if->vgic_vmcr = readl_relaxed(base + GICH_VMCR);
-
 	if (vcpu->arch.vgic_cpu.live_lrs) {
 		cpu_if->vgic_apr = readl_relaxed(base + GICH_APR);
 
@@ -165,7 +163,6 @@ void __hyp_text __vgic_v2_restore_state(struct kvm_vcpu *vcpu)
 		}
 	}
 
-	writel_relaxed(cpu_if->vgic_vmcr, base + GICH_VMCR);
 	vcpu->arch.vgic_cpu.live_lrs = live_lrs;
 }
 
diff --git a/virt/kvm/arm/hyp/vgic-v3-sr.c b/virt/kvm/arm/hyp/vgic-v3-sr.c
index 3947095..e51ee7e 100644
--- a/virt/kvm/arm/hyp/vgic-v3-sr.c
+++ b/virt/kvm/arm/hyp/vgic-v3-sr.c
@@ -159,8 +159,6 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
 	if (!cpu_if->vgic_sre)
 		dsb(st);
 
-	cpu_if->vgic_vmcr  = read_gicreg(ICH_VMCR_EL2);
-
 	if (vcpu->arch.vgic_cpu.live_lrs) {
 		int i;
 		u32 max_lr_idx, nr_pri_bits;
@@ -261,8 +259,6 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)
 			live_lrs |= (1 << i);
 	}
 
-	write_gicreg(cpu_if->vgic_vmcr, ICH_VMCR_EL2);
-
 	if (live_lrs) {
 		write_gicreg(cpu_if->vgic_hcr, ICH_HCR_EL2);
 
@@ -326,3 +322,13 @@ u64 __hyp_text __vgic_v3_get_ich_vtr_el2(void)
 {
 	return read_gicreg(ICH_VTR_EL2);
 }
+
+u64 __hyp_text __vgic_v3_read_vmcr(void)
+{
+	return read_gicreg(ICH_VMCR_EL2);
+}
+
+void __hyp_text __vgic_v3_write_vmcr(u32 vmcr)
+{
+	write_gicreg(vmcr, ICH_VMCR_EL2);
+}
diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
index 702f810..3762fd1 100644
--- a/virt/kvm/arm/vgic/vgic-init.c
+++ b/virt/kvm/arm/vgic/vgic-init.c
@@ -262,6 +262,18 @@ int vgic_init(struct kvm *kvm)
 	vgic_debug_init(kvm);
 
 	dist->initialized = true;
+
+	/*
+	 * If we're initializing GICv2 on-demand when first running the VCPU
+	 * then we need to load the VGIC state onto the CPU.  We can detect
+	 * this easily by checking if we are in between vcpu_load and vcpu_put
+	 * when we just initialized the VGIC.
+	 */
+	preempt_disable();
+	vcpu = kvm_arm_get_running_vcpu();
+	if (vcpu)
+		kvm_vgic_load(vcpu);
+	preempt_enable();
 out:
 	return ret;
 }
diff --git a/virt/kvm/arm/vgic/vgic-v2.c b/virt/kvm/arm/vgic/vgic-v2.c
index 94cf4b9..5c91552 100644
--- a/virt/kvm/arm/vgic/vgic-v2.c
+++ b/virt/kvm/arm/vgic/vgic-v2.c
@@ -199,6 +199,7 @@ void vgic_v2_clear_lr(struct kvm_vcpu *vcpu, int lr)
 
 void vgic_v2_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcrp)
 {
+	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
 	u32 vmcr;
 
 	vmcr  = (vmcrp->ctlr << GICH_VMCR_CTRL_SHIFT) & GICH_VMCR_CTRL_MASK;
@@ -209,12 +210,15 @@ void vgic_v2_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcrp)
 	vmcr |= (vmcrp->pmr << GICH_VMCR_PRIMASK_SHIFT) &
 		GICH_VMCR_PRIMASK_MASK;
 
-	vcpu->arch.vgic_cpu.vgic_v2.vgic_vmcr = vmcr;
+	cpu_if->vgic_vmcr = vmcr;
 }
 
 void vgic_v2_get_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcrp)
 {
-	u32 vmcr = vcpu->arch.vgic_cpu.vgic_v2.vgic_vmcr;
+	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
+	u32 vmcr;
+
+	vmcr = cpu_if->vgic_vmcr;
 
 	vmcrp->ctlr = (vmcr & GICH_VMCR_CTRL_MASK) >>
 			GICH_VMCR_CTRL_SHIFT;
@@ -390,3 +394,19 @@ int vgic_v2_probe(const struct gic_kvm_info *info)
 
 	return ret;
 }
+
+void vgic_v2_load(struct kvm_vcpu *vcpu)
+{
+	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
+	struct vgic_dist *vgic = &vcpu->kvm->arch.vgic;
+
+	writel_relaxed(cpu_if->vgic_vmcr, vgic->vctrl_base + GICH_VMCR);
+}
+
+void vgic_v2_put(struct kvm_vcpu *vcpu)
+{
+	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
+	struct vgic_dist *vgic = &vcpu->kvm->arch.vgic;
+
+	cpu_if->vgic_vmcr = readl_relaxed(vgic->vctrl_base + GICH_VMCR);
+}
diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index edc6ee2..0baef2d 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -173,6 +173,7 @@ void vgic_v3_clear_lr(struct kvm_vcpu *vcpu, int lr)
 
 void vgic_v3_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcrp)
 {
+	struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
 	u32 vmcr;
 
 	/*
@@ -188,12 +189,15 @@ void vgic_v3_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcrp)
 	vmcr |= (vmcrp->grpen0 << ICH_VMCR_ENG0_SHIFT) & ICH_VMCR_ENG0_MASK;
 	vmcr |= (vmcrp->grpen1 << ICH_VMCR_ENG1_SHIFT) & ICH_VMCR_ENG1_MASK;
 
-	vcpu->arch.vgic_cpu.vgic_v3.vgic_vmcr = vmcr;
+	cpu_if->vgic_vmcr = vmcr;
 }
 
 void vgic_v3_get_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcrp)
 {
-	u32 vmcr = vcpu->arch.vgic_cpu.vgic_v3.vgic_vmcr;
+	struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
+	u32 vmcr;
+
+	vmcr = cpu_if->vgic_vmcr;
 
 	/*
 	 * Ignore the FIQen bit, because GIC emulation always implies
@@ -383,3 +387,17 @@ int vgic_v3_probe(const struct gic_kvm_info *info)
 
 	return 0;
 }
+
+void vgic_v3_load(struct kvm_vcpu *vcpu)
+{
+	struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
+
+	kvm_call_hyp(__vgic_v3_write_vmcr, cpu_if->vgic_vmcr);
+}
+
+void vgic_v3_put(struct kvm_vcpu *vcpu)
+{
+	struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
+
+	cpu_if->vgic_vmcr = kvm_call_hyp(__vgic_v3_read_vmcr);
+}
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 654dfd4..2ac0def 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -656,6 +656,28 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
 	spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
 }
 
+void kvm_vgic_load(struct kvm_vcpu *vcpu)
+{
+	if (unlikely(!vgic_initialized(vcpu->kvm)))
+		return;
+
+	if (kvm_vgic_global_state.type == VGIC_V2)
+		vgic_v2_load(vcpu);
+	else
+		vgic_v3_load(vcpu);
+}
+
+void kvm_vgic_put(struct kvm_vcpu *vcpu)
+{
+	if (unlikely(!vgic_initialized(vcpu->kvm)))
+		return;
+
+	if (kvm_vgic_global_state.type == VGIC_V2)
+		vgic_v2_put(vcpu);
+	else
+		vgic_v3_put(vcpu);
+}
+
 int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu)
 {
 	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
index 91566f5..3f64220 100644
--- a/virt/kvm/arm/vgic/vgic.h
+++ b/virt/kvm/arm/vgic/vgic.h
@@ -132,6 +132,9 @@ int vgic_register_dist_iodev(struct kvm *kvm, gpa_t dist_base_address,
 
 void vgic_v2_init_lrs(void);
 
+void vgic_v2_load(struct kvm_vcpu *vcpu);
+void vgic_v2_put(struct kvm_vcpu *vcpu);
+
 static inline void vgic_get_irq_kref(struct vgic_irq *irq)
 {
 	if (irq->intid < VGIC_MIN_LPI)
@@ -152,6 +155,9 @@ int vgic_v3_probe(const struct gic_kvm_info *info);
 int vgic_v3_map_resources(struct kvm *kvm);
 int vgic_register_redist_iodevs(struct kvm *kvm, gpa_t dist_base_address);
 
+void vgic_v3_load(struct kvm_vcpu *vcpu);
+void vgic_v3_put(struct kvm_vcpu *vcpu);
+
 int vgic_register_its_iodevs(struct kvm *kvm);
 bool vgic_has_its(struct kvm *kvm);
 int kvm_vgic_register_its_device(void);
-- 
2.9.0

[PATCH v2 02/10] KVM: arm/arm64: vgic: Avoid flushing vgic state when there's no pending IRQ

[Christoffer Dall]

From: Shih-Wei Li <shihwei@cs.columbia.edu>

We do not need to flush vgic states in each world switch unless
there is pending IRQ queued to the vgic's ap list. We can thus reduce
the overhead by not grabbing the spinlock and not making the extra
function call to vgic_flush_lr_state.

Note: list_empty is a single atomic read (uses READ_ONCE) and can
therefore check if a list is empty or not without the need to take the
spinlock protecting the list.

Signed-off-by: Shih-Wei Li <shihwei@cs.columbia.edu>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
---
Changes since v1:
 - Added comment in kvm_vgic_flush_hwstate

 virt/kvm/arm/vgic/vgic.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 2ac0def..1043291 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -637,12 +637,17 @@ static void vgic_flush_lr_state(struct kvm_vcpu *vcpu)
 /* Sync back the hardware VGIC state into our emulation after a guest's run. */
 void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
 {
+	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+
 	if (unlikely(!vgic_initialized(vcpu->kvm)))
 		return;
 
 	vgic_process_maintenance_interrupt(vcpu);
 	vgic_fold_lr_state(vcpu);
 	vgic_prune_ap_list(vcpu);
+
+	/* Make sure we can fast-path in flush_hwstate */
+	vgic_cpu->used_lrs = 0;
 }
 
 /* Flush our emulation state into the GIC hardware before entering the guest. */
@@ -651,6 +656,18 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
 	if (unlikely(!vgic_initialized(vcpu->kvm)))
 		return;
 
+	/*
+	 * If there are no virtual interrupts active or pending for this
+	 * VCPU, then there is no work to do and we can bail out without
+	 * taking any lock.  There is a potential race with someone injecting
+	 * interrupts to the VCPU, but it is a benign race as the VCPU will
+	 * either observe the new interrupt before or after doing this check,
+	 * and introducing additional synchronization mechanism doesn't change
+	 * this.
+	 */
+	if (list_empty(&vcpu->arch.vgic_cpu.ap_list_head))
+		return;
+
 	spin_lock(&vcpu->arch.vgic_cpu.ap_list_lock);
 	vgic_flush_lr_state(vcpu);
 	spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
-- 
2.9.0

[PATCH v2 03/10] KVM: arm/arm64: vgic: Get rid of live_lrs

[Christoffer Dall]

From: Christoffer Dall <christoffer.dall@linaro.org>

There is no need to calculate and maintain live_lrs when we always
populate the lowest numbered LRs first on every entry and clear all LRs
on every exit.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 include/kvm/arm_vgic.h        |  2 --
 virt/kvm/arm/hyp/vgic-v2-sr.c | 39 ++++++++++-----------------------------
 virt/kvm/arm/hyp/vgic-v3-sr.c | 42 ++++++++++++------------------------------
 3 files changed, 22 insertions(+), 61 deletions(-)

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 8d7c3a7..fa12d99 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -264,8 +264,6 @@ struct vgic_cpu {
 	 */
 	struct list_head ap_list_head;
 
-	u64 live_lrs;
-
 	/*
 	 * Members below are used with GICv3 emulation only and represent
 	 * parts of the redistributor.
diff --git a/virt/kvm/arm/hyp/vgic-v2-sr.c b/virt/kvm/arm/hyp/vgic-v2-sr.c
index d3d3b9b..34b37ce 100644
--- a/virt/kvm/arm/hyp/vgic-v2-sr.c
+++ b/virt/kvm/arm/hyp/vgic-v2-sr.c
@@ -26,27 +26,23 @@ static void __hyp_text save_maint_int_state(struct kvm_vcpu *vcpu,
 					    void __iomem *base)
 {
 	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
-	int nr_lr = (kern_hyp_va(&kvm_vgic_global_state))->nr_lr;
+	u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
 	u32 eisr0, eisr1;
 	int i;
 	bool expect_mi;
 
 	expect_mi = !!(cpu_if->vgic_hcr & GICH_HCR_UIE);
 
-	for (i = 0; i < nr_lr; i++) {
-		if (!(vcpu->arch.vgic_cpu.live_lrs & (1UL << i)))
-				continue;
-
+	for (i = 0; i < used_lrs && !expect_mi; i++)
 		expect_mi |= (!(cpu_if->vgic_lr[i] & GICH_LR_HW) &&
 			      (cpu_if->vgic_lr[i] & GICH_LR_EOI));
-	}
 
 	if (expect_mi) {
 		cpu_if->vgic_misr = readl_relaxed(base + GICH_MISR);
 
 		if (cpu_if->vgic_misr & GICH_MISR_EOI) {
 			eisr0  = readl_relaxed(base + GICH_EISR0);
-			if (unlikely(nr_lr > 32))
+			if (unlikely(used_lrs > 32))
 				eisr1  = readl_relaxed(base + GICH_EISR1);
 			else
 				eisr1 = 0;
@@ -87,13 +83,10 @@ static void __hyp_text save_elrsr(struct kvm_vcpu *vcpu, void __iomem *base)
 static void __hyp_text save_lrs(struct kvm_vcpu *vcpu, void __iomem *base)
 {
 	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
-	int nr_lr = (kern_hyp_va(&kvm_vgic_global_state))->nr_lr;
 	int i;
+	u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
 
-	for (i = 0; i < nr_lr; i++) {
-		if (!(vcpu->arch.vgic_cpu.live_lrs & (1UL << i)))
-			continue;
-
+	for (i = 0; i < used_lrs; i++) {
 		if (cpu_if->vgic_elrsr & (1UL << i))
 			cpu_if->vgic_lr[i] &= ~GICH_LR_STATE;
 		else
@@ -110,11 +103,12 @@ void __hyp_text __vgic_v2_save_state(struct kvm_vcpu *vcpu)
 	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
 	struct vgic_dist *vgic = &kvm->arch.vgic;
 	void __iomem *base = kern_hyp_va(vgic->vctrl_base);
+	u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
 
 	if (!base)
 		return;
 
-	if (vcpu->arch.vgic_cpu.live_lrs) {
+	if (used_lrs) {
 		cpu_if->vgic_apr = readl_relaxed(base + GICH_APR);
 
 		save_maint_int_state(vcpu, base);
@@ -122,8 +116,6 @@ void __hyp_text __vgic_v2_save_state(struct kvm_vcpu *vcpu)
 		save_lrs(vcpu, base);
 
 		writel_relaxed(0, base + GICH_HCR);
-
-		vcpu->arch.vgic_cpu.live_lrs = 0;
 	} else {
 		cpu_if->vgic_eisr = 0;
 		cpu_if->vgic_elrsr = ~0UL;
@@ -139,31 +131,20 @@ void __hyp_text __vgic_v2_restore_state(struct kvm_vcpu *vcpu)
 	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
 	struct vgic_dist *vgic = &kvm->arch.vgic;
 	void __iomem *base = kern_hyp_va(vgic->vctrl_base);
-	int nr_lr = (kern_hyp_va(&kvm_vgic_global_state))->nr_lr;
 	int i;
-	u64 live_lrs = 0;
+	u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
 
 	if (!base)
 		return;
 
-
-	for (i = 0; i < nr_lr; i++)
-		if (cpu_if->vgic_lr[i] & GICH_LR_STATE)
-			live_lrs |= 1UL << i;
-
-	if (live_lrs) {
+	if (used_lrs) {
 		writel_relaxed(cpu_if->vgic_hcr, base + GICH_HCR);
 		writel_relaxed(cpu_if->vgic_apr, base + GICH_APR);
-		for (i = 0; i < nr_lr; i++) {
-			if (!(live_lrs & (1UL << i)))
-				continue;
-
+		for (i = 0; i < used_lrs; i++) {
 			writel_relaxed(cpu_if->vgic_lr[i],
 				       base + GICH_LR0 + (i * 4));
 		}
 	}
-
-	vcpu->arch.vgic_cpu.live_lrs = live_lrs;
 }
 
 #ifdef CONFIG_ARM64
diff --git a/virt/kvm/arm/hyp/vgic-v3-sr.c b/virt/kvm/arm/hyp/vgic-v3-sr.c
index e51ee7e..b3c36b6 100644
--- a/virt/kvm/arm/hyp/vgic-v3-sr.c
+++ b/virt/kvm/arm/hyp/vgic-v3-sr.c
@@ -118,18 +118,16 @@ static void __hyp_text __gic_v3_set_lr(u64 val, int lr)
 	}
 }
 
-static void __hyp_text save_maint_int_state(struct kvm_vcpu *vcpu, int nr_lr)
+static void __hyp_text save_maint_int_state(struct kvm_vcpu *vcpu)
 {
 	struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
 	int i;
 	bool expect_mi;
+	u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
 
 	expect_mi = !!(cpu_if->vgic_hcr & ICH_HCR_UIE);
 
-	for (i = 0; i < nr_lr; i++) {
-		if (!(vcpu->arch.vgic_cpu.live_lrs & (1UL << i)))
-				continue;
-
+	for (i = 0; i < used_lrs; i++) {
 		expect_mi |= (!(cpu_if->vgic_lr[i] & ICH_LR_HW) &&
 			      (cpu_if->vgic_lr[i] & ICH_LR_EOI));
 	}
@@ -150,6 +148,7 @@ static void __hyp_text save_maint_int_state(struct kvm_vcpu *vcpu, int nr_lr)
 void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
 {
 	struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
+	u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
 	u64 val;
 
 	/*
@@ -159,23 +158,19 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
 	if (!cpu_if->vgic_sre)
 		dsb(st);
 
-	if (vcpu->arch.vgic_cpu.live_lrs) {
+	if (used_lrs) {
 		int i;
-		u32 max_lr_idx, nr_pri_bits;
+		u32 nr_pri_bits;
 
 		cpu_if->vgic_elrsr = read_gicreg(ICH_ELSR_EL2);
 
 		write_gicreg(0, ICH_HCR_EL2);
 		val = read_gicreg(ICH_VTR_EL2);
-		max_lr_idx = vtr_to_max_lr_idx(val);
 		nr_pri_bits = vtr_to_nr_pri_bits(val);
 
-		save_maint_int_state(vcpu, max_lr_idx + 1);
-
-		for (i = 0; i <= max_lr_idx; i++) {
-			if (!(vcpu->arch.vgic_cpu.live_lrs & (1UL << i)))
-				continue;
+		save_maint_int_state(vcpu);
 
+		for (i = 0; i <= used_lrs; i++) {
 			if (cpu_if->vgic_elrsr & (1 << i))
 				cpu_if->vgic_lr[i] &= ~ICH_LR_STATE;
 			else
@@ -203,8 +198,6 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
 		default:
 			cpu_if->vgic_ap1r[0] = read_gicreg(ICH_AP1R0_EL2);
 		}
-
-		vcpu->arch.vgic_cpu.live_lrs = 0;
 	} else {
 		cpu_if->vgic_misr  = 0;
 		cpu_if->vgic_eisr  = 0;
@@ -232,9 +225,9 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
 void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)
 {
 	struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
+	u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
 	u64 val;
-	u32 max_lr_idx, nr_pri_bits;
-	u16 live_lrs = 0;
+	u32 nr_pri_bits;
 	int i;
 
 	/*
@@ -251,15 +244,9 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)
 	}
 
 	val = read_gicreg(ICH_VTR_EL2);
-	max_lr_idx = vtr_to_max_lr_idx(val);
 	nr_pri_bits = vtr_to_nr_pri_bits(val);
 
-	for (i = 0; i <= max_lr_idx; i++) {
-		if (cpu_if->vgic_lr[i] & ICH_LR_STATE)
-			live_lrs |= (1 << i);
-	}
-
-	if (live_lrs) {
+	if (used_lrs) {
 		write_gicreg(cpu_if->vgic_hcr, ICH_HCR_EL2);
 
 		switch (nr_pri_bits) {
@@ -282,12 +269,8 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)
 			write_gicreg(cpu_if->vgic_ap1r[0], ICH_AP1R0_EL2);
 		}
 
-		for (i = 0; i <= max_lr_idx; i++) {
-			if (!(live_lrs & (1 << i)))
-				continue;
-
+		for (i = 0; i < used_lrs; i++)
 			__gic_v3_set_lr(cpu_if->vgic_lr[i], i);
-		}
 	}
 
 	/*
@@ -299,7 +282,6 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)
 		isb();
 		dsb(sy);
 	}
-	vcpu->arch.vgic_cpu.live_lrs = live_lrs;
 
 	/*
 	 * Prevent the guest from touching the GIC system registers if
-- 
2.9.0

[PATCH v2 04/10] KVM: arm/arm64: vgic: Only set underflow when actually out of LRs

[Christoffer Dall]

We currently assume that all the interrupts in our AP list will be
queued to LRs, but that's not necessarily the case, because some of them
could have been migrated away to different VCPUs and only the VCPU
thread itself can remove interrupts from its AP list.

Therefore, slightly change the logic to only setting the underflow
interrupt when we actually run out of LRs.

As it turns out, this allows us to further simplify the handling in
vgic_sync_hwstate in later patches.

Signed-off-by: Christoffer Dall <cdall@linaro.org>
---
Changes since v1:
 - New patch

 virt/kvm/arm/vgic/vgic.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 1043291..442f7df 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -601,10 +601,8 @@ static void vgic_flush_lr_state(struct kvm_vcpu *vcpu)
 
 	DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&vgic_cpu->ap_list_lock));
 
-	if (compute_ap_list_depth(vcpu) > kvm_vgic_global_state.nr_lr) {
-		vgic_set_underflow(vcpu);
+	if (compute_ap_list_depth(vcpu) > kvm_vgic_global_state.nr_lr)
 		vgic_sort_ap_list(vcpu);
-	}
 
 	list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list) {
 		spin_lock(&irq->irq_lock);
@@ -623,8 +621,12 @@ static void vgic_flush_lr_state(struct kvm_vcpu *vcpu)
 next:
 		spin_unlock(&irq->irq_lock);
 
-		if (count == kvm_vgic_global_state.nr_lr)
+		if (count == kvm_vgic_global_state.nr_lr) {
+			if (!list_is_last(&irq->ap_list,
+					  &vgic_cpu->ap_list_head))
+				vgic_set_underflow(vcpu);
 			break;
+		}
 	}
 
 	vcpu->arch.vgic_cpu.used_lrs = count;
-- 
2.9.0

[PATCH v2 05/10] KVM: arm/arm64: vgic: Get rid of unnecessary process_maintenance operation

[Christoffer Dall]

From: Christoffer Dall <christoffer.dall@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.

We now clear the underflow bit in the fold_lr_state functions as we only
need to clear this bit if we had used all the LRs, so this is as good a
place as any to do that work.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
Changes since v1:
 - Moved the clearing of the UIE bit into fold_lr_state
   [Did not apply Marc's reviewed-by tag as the patch changed enough
    to not carry that forward.]

 virt/kvm/arm/vgic/vgic-v2.c | 59 +++++++++------------------------------------
 virt/kvm/arm/vgic/vgic-v3.c | 51 ++++++++++-----------------------------
 virt/kvm/arm/vgic/vgic.c    |  9 -------
 virt/kvm/arm/vgic/vgic.h    |  2 --
 4 files changed, 25 insertions(+), 96 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-v2.c b/virt/kvm/arm/vgic/vgic-v2.c
index 5c91552..f9c4329 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;
-}
-
 static inline void vgic_v2_write_lr(int lr, u32 val)
 {
 	void __iomem *base = kvm_vgic_global_state.vctrl_base;
@@ -51,45 +37,17 @@ void vgic_v2_init_lrs(void)
 		vgic_v2_write_lr(i, 0);
 }
 
-void vgic_v2_process_maintenance(struct kvm_vcpu *vcpu)
+void vgic_v2_set_underflow(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;
+	cpuif->vgic_hcr |= GICH_HCR_UIE;
 }
 
-void vgic_v2_set_underflow(struct kvm_vcpu *vcpu)
+static bool lr_signals_eoi_mi(u32 lr_val)
 {
-	struct vgic_v2_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v2;
-
-	cpuif->vgic_hcr |= GICH_HCR_UIE;
+	return !(lr_val & GICH_LR_STATE) && (lr_val & GICH_LR_EOI) &&
+	       !(lr_val & GICH_LR_HW);
 }
 
 /*
@@ -104,11 +62,18 @@ void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu)
 	struct vgic_v2_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v2;
 	int lr;
 
+	cpuif->vgic_hcr &= ~GICH_HCR_UIE;
+
 	for (lr = 0; lr < vcpu->arch.vgic_cpu.used_lrs; lr++) {
 		u32 val = cpuif->vgic_lr[lr];
 		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 0baef2d..c7ac9b1 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -21,50 +21,17 @@
 
 #include "vgic.h"
 
-void vgic_v3_process_maintenance(struct kvm_vcpu *vcpu)
+void vgic_v3_set_underflow(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;
+	cpuif->vgic_hcr |= ICH_HCR_UIE;
 }
 
-void vgic_v3_set_underflow(struct kvm_vcpu *vcpu)
+static bool lr_signals_eoi_mi(u64 lr_val)
 {
-	struct vgic_v3_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v3;
-
-	cpuif->vgic_hcr |= ICH_HCR_UIE;
+	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)
@@ -73,6 +40,8 @@ void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu)
 	u32 model = vcpu->kvm->arch.vgic.vgic_model;
 	int lr;
 
+	cpuif->vgic_hcr &= ~ICH_HCR_UIE;
+
 	for (lr = 0; lr < vcpu->arch.vgic_cpu.used_lrs; lr++) {
 		u64 val = cpuif->vgic_lr[lr];
 		u32 intid;
@@ -82,6 +51,12 @@ 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 442f7df..b64b143 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -527,14 +527,6 @@ 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)
-{
-	if (kvm_vgic_global_state.type == VGIC_V2)
-		vgic_v2_process_maintenance(vcpu);
-	else
-		vgic_v3_process_maintenance(vcpu);
-}
-
 static inline void vgic_fold_lr_state(struct kvm_vcpu *vcpu)
 {
 	if (kvm_vgic_global_state.type == VGIC_V2)
@@ -644,7 +636,6 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
 	if (unlikely(!vgic_initialized(vcpu->kvm)))
 		return;
 
-	vgic_process_maintenance_interrupt(vcpu);
 	vgic_fold_lr_state(vcpu);
 	vgic_prune_ap_list(vcpu);
 
diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
index 3f64220..63b67e8 100644
--- a/virt/kvm/arm/vgic/vgic.h
+++ b/virt/kvm/arm/vgic/vgic.h
@@ -112,7 +112,6 @@ 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_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 +142,6 @@ 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_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);
-- 
2.9.0

[PATCH v2 06/10] KVM: arm/arm64: vgic: Get rid of unnecessary save_maint_int_state

[Christoffer Dall]

From: Christoffer Dall <christoffer.dall@linaro.org>

Now when we don't look at the MISR and EISR values anymore, we can get
rid of the logic to save them in the GIC save/restore code.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 virt/kvm/arm/hyp/vgic-v2-sr.c | 40 ----------------------------------------
 virt/kvm/arm/hyp/vgic-v3-sr.c | 29 -----------------------------
 2 files changed, 69 deletions(-)

diff --git a/virt/kvm/arm/hyp/vgic-v2-sr.c b/virt/kvm/arm/hyp/vgic-v2-sr.c
index 34b37ce..a4c3bb0 100644
--- a/virt/kvm/arm/hyp/vgic-v2-sr.c
+++ b/virt/kvm/arm/hyp/vgic-v2-sr.c
@@ -22,45 +22,6 @@
 #include <asm/kvm_emulate.h>
 #include <asm/kvm_hyp.h>
 
-static void __hyp_text save_maint_int_state(struct kvm_vcpu *vcpu,
-					    void __iomem *base)
-{
-	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
-	u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
-	u32 eisr0, eisr1;
-	int i;
-	bool expect_mi;
-
-	expect_mi = !!(cpu_if->vgic_hcr & GICH_HCR_UIE);
-
-	for (i = 0; i < used_lrs && !expect_mi; i++)
-		expect_mi |= (!(cpu_if->vgic_lr[i] & GICH_LR_HW) &&
-			      (cpu_if->vgic_lr[i] & GICH_LR_EOI));
-
-	if (expect_mi) {
-		cpu_if->vgic_misr = readl_relaxed(base + GICH_MISR);
-
-		if (cpu_if->vgic_misr & GICH_MISR_EOI) {
-			eisr0  = readl_relaxed(base + GICH_EISR0);
-			if (unlikely(used_lrs > 32))
-				eisr1  = readl_relaxed(base + GICH_EISR1);
-			else
-				eisr1 = 0;
-		} else {
-			eisr0 = eisr1 = 0;
-		}
-	} else {
-		cpu_if->vgic_misr = 0;
-		eisr0 = eisr1 = 0;
-	}
-
-#ifdef CONFIG_CPU_BIG_ENDIAN
-	cpu_if->vgic_eisr = ((u64)eisr0 << 32) | eisr1;
-#else
-	cpu_if->vgic_eisr = ((u64)eisr1 << 32) | eisr0;
-#endif
-}
-
 static void __hyp_text save_elrsr(struct kvm_vcpu *vcpu, void __iomem *base)
 {
 	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
@@ -111,7 +72,6 @@ void __hyp_text __vgic_v2_save_state(struct kvm_vcpu *vcpu)
 	if (used_lrs) {
 		cpu_if->vgic_apr = readl_relaxed(base + GICH_APR);
 
-		save_maint_int_state(vcpu, base);
 		save_elrsr(vcpu, base);
 		save_lrs(vcpu, base);
 
diff --git a/virt/kvm/arm/hyp/vgic-v3-sr.c b/virt/kvm/arm/hyp/vgic-v3-sr.c
index b3c36b6..41bbbb0 100644
--- a/virt/kvm/arm/hyp/vgic-v3-sr.c
+++ b/virt/kvm/arm/hyp/vgic-v3-sr.c
@@ -118,33 +118,6 @@ static void __hyp_text __gic_v3_set_lr(u64 val, int lr)
 	}
 }
 
-static void __hyp_text save_maint_int_state(struct kvm_vcpu *vcpu)
-{
-	struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
-	int i;
-	bool expect_mi;
-	u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
-
-	expect_mi = !!(cpu_if->vgic_hcr & ICH_HCR_UIE);
-
-	for (i = 0; i < used_lrs; i++) {
-		expect_mi |= (!(cpu_if->vgic_lr[i] & ICH_LR_HW) &&
-			      (cpu_if->vgic_lr[i] & ICH_LR_EOI));
-	}
-
-	if (expect_mi) {
-		cpu_if->vgic_misr  = read_gicreg(ICH_MISR_EL2);
-
-		if (cpu_if->vgic_misr & ICH_MISR_EOI)
-			cpu_if->vgic_eisr = read_gicreg(ICH_EISR_EL2);
-		else
-			cpu_if->vgic_eisr = 0;
-	} else {
-		cpu_if->vgic_misr = 0;
-		cpu_if->vgic_eisr = 0;
-	}
-}
-
 void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
 {
 	struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
@@ -168,8 +141,6 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
 		val = read_gicreg(ICH_VTR_EL2);
 		nr_pri_bits = vtr_to_nr_pri_bits(val);
 
-		save_maint_int_state(vcpu);
-
 		for (i = 0; i <= used_lrs; i++) {
 			if (cpu_if->vgic_elrsr & (1 << i))
 				cpu_if->vgic_lr[i] &= ~ICH_LR_STATE;
-- 
2.9.0

[PATCH v2 07/10] KVM: arm/arm64: vgic: Get rid of MISR and EISR fields

[Christoffer Dall]

From: Christoffer Dall <christoffer.dall@linaro.org>

We don't use these fields anymore so let's nuke them completely.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 include/kvm/arm_vgic.h        | 4 ----
 virt/kvm/arm/hyp/vgic-v2-sr.c | 2 --
 virt/kvm/arm/hyp/vgic-v3-sr.c | 2 --
 3 files changed, 8 deletions(-)

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index fa12d99..581a59e 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -225,8 +225,6 @@ struct vgic_dist {
 struct vgic_v2_cpu_if {
 	u32		vgic_hcr;
 	u32		vgic_vmcr;
-	u32		vgic_misr;	/* Saved only */
-	u64		vgic_eisr;	/* Saved only */
 	u64		vgic_elrsr;	/* Saved only */
 	u32		vgic_apr;
 	u32		vgic_lr[VGIC_V2_MAX_LRS];
@@ -236,8 +234,6 @@ struct vgic_v3_cpu_if {
 	u32		vgic_hcr;
 	u32		vgic_vmcr;
 	u32		vgic_sre;	/* Restored only, change ignored */
-	u32		vgic_misr;	/* Saved only */
-	u32		vgic_eisr;	/* Saved only */
 	u32		vgic_elrsr;	/* Saved only */
 	u32		vgic_ap0r[4];
 	u32		vgic_ap1r[4];
diff --git a/virt/kvm/arm/hyp/vgic-v2-sr.c b/virt/kvm/arm/hyp/vgic-v2-sr.c
index a4c3bb0..a3f18d3 100644
--- a/virt/kvm/arm/hyp/vgic-v2-sr.c
+++ b/virt/kvm/arm/hyp/vgic-v2-sr.c
@@ -77,9 +77,7 @@ void __hyp_text __vgic_v2_save_state(struct kvm_vcpu *vcpu)
 
 		writel_relaxed(0, base + GICH_HCR);
 	} else {
-		cpu_if->vgic_eisr = 0;
 		cpu_if->vgic_elrsr = ~0UL;
-		cpu_if->vgic_misr = 0;
 		cpu_if->vgic_apr = 0;
 	}
 }
diff --git a/virt/kvm/arm/hyp/vgic-v3-sr.c b/virt/kvm/arm/hyp/vgic-v3-sr.c
index 41bbbb0..3d0b1dd 100644
--- a/virt/kvm/arm/hyp/vgic-v3-sr.c
+++ b/virt/kvm/arm/hyp/vgic-v3-sr.c
@@ -170,8 +170,6 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
 			cpu_if->vgic_ap1r[0] = read_gicreg(ICH_AP1R0_EL2);
 		}
 	} else {
-		cpu_if->vgic_misr  = 0;
-		cpu_if->vgic_eisr  = 0;
 		cpu_if->vgic_elrsr = 0xffff;
 		cpu_if->vgic_ap0r[0] = 0;
 		cpu_if->vgic_ap0r[1] = 0;
-- 
2.9.0

[PATCH v2 08/10] KVM: arm/arm64: vgic: Implement early VGIC init functionality

[Christoffer Dall]

Implement early initialization for both the distributor and the CPU
interfaces.  The basic idea is that even though the VGIC is not
functional or not requested from user space, the critical path of the
run loop can still call VGIC functions that just won't do anything,
without them having to check additional initialization flags to ensure
they don't look at uninitialized data structures.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
---
 virt/kvm/arm/vgic/vgic-init.c | 96 +++++++++++++++++++++++++------------------
 1 file changed, 56 insertions(+), 40 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
index 3762fd1..25fd1b9 100644
--- a/virt/kvm/arm/vgic/vgic-init.c
+++ b/virt/kvm/arm/vgic/vgic-init.c
@@ -24,7 +24,12 @@
 
 /*
  * Initialization rules: there are multiple stages to the vgic
- * initialization, both for the distributor and the CPU interfaces.
+ * initialization, both for the distributor and the CPU interfaces.  The basic
+ * idea is that even though the VGIC is not functional or not requested from
+ * user space, the critical path of the run loop can still call VGIC functions
+ * that just won't do anything, without them having to check additional
+ * initialization flags to ensure they don't look at uninitialized data
+ * structures.
  *
  * Distributor:
  *
@@ -39,23 +44,67 @@
  *
  * CPU Interface:
  *
- * - kvm_vgic_cpu_early_init(): initialization of static data that
+ * - kvm_vgic_vcpu_early_init(): initialization of static data that
  *   doesn't depend on any sizing information or emulation type. No
  *   allocation is allowed there.
  */
 
 /* EARLY INIT */
 
-/*
- * Those 2 functions should not be needed anymore but they
- * still are called from arm.c
+/**
+ * kvm_vgic_early_init() - Initialize static VGIC VCPU data structures
+ * @kvm: The VM whose VGIC districutor should be initialized
+ *
+ * Only do initialization of static structures that don't require any
+ * allocation or sizing information from userspace.  vgic_init() called
+ * kvm_vgic_dist_init() which takes care of the rest.
  */
 void kvm_vgic_early_init(struct kvm *kvm)
 {
+	struct vgic_dist *dist = &kvm->arch.vgic;
+
+	INIT_LIST_HEAD(&dist->lpi_list_head);
+	spin_lock_init(&dist->lpi_list_lock);
 }
 
+/**
+ * kvm_vgic_vcpu_early_init() - Initialize static VGIC VCPU data structures
+ * @vcpu: The VCPU whose VGIC data structures whould be initialized
+ *
+ * Only do initialization, but do not actually enable the VGIC CPU interface
+ * yet.
+ */
 void kvm_vgic_vcpu_early_init(struct kvm_vcpu *vcpu)
 {
+	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+	int i;
+
+	INIT_LIST_HEAD(&vgic_cpu->ap_list_head);
+	spin_lock_init(&vgic_cpu->ap_list_lock);
+
+	/*
+	 * Enable and configure all SGIs to be edge-triggered and
+	 * configure all PPIs as level-triggered.
+	 */
+	for (i = 0; i < VGIC_NR_PRIVATE_IRQS; i++) {
+		struct vgic_irq *irq = &vgic_cpu->private_irqs[i];
+
+		INIT_LIST_HEAD(&irq->ap_list);
+		spin_lock_init(&irq->irq_lock);
+		irq->intid = i;
+		irq->vcpu = NULL;
+		irq->target_vcpu = vcpu;
+		irq->targets = 1U << vcpu->vcpu_id;
+		kref_init(&irq->refcount);
+		if (vgic_irq_is_sgi(i)) {
+			/* SGIs */
+			irq->enabled = 1;
+			irq->config = VGIC_CONFIG_EDGE;
+		} else {
+			/* PPIs */
+			irq->config = VGIC_CONFIG_LEVEL;
+		}
+	}
 }
 
 /* CREATION */
@@ -148,9 +197,6 @@ static int kvm_vgic_dist_init(struct kvm *kvm, unsigned int nr_spis)
 	struct kvm_vcpu *vcpu0 = kvm_get_vcpu(kvm, 0);
 	int i;
 
-	INIT_LIST_HEAD(&dist->lpi_list_head);
-	spin_lock_init(&dist->lpi_list_lock);
-
 	dist->spis = kcalloc(nr_spis, sizeof(struct vgic_irq), GFP_KERNEL);
 	if (!dist->spis)
 		return  -ENOMEM;
@@ -181,41 +227,11 @@ static int kvm_vgic_dist_init(struct kvm *kvm, unsigned int nr_spis)
 }
 
 /**
- * kvm_vgic_vcpu_init: initialize the vcpu data structures and
- * enable the VCPU interface
- * @vcpu: the VCPU which's VGIC should be initialized
+ * kvm_vgic_vcpu_init() - Enable the VCPU interface
+ * @vcpu: the VCPU which's VGIC should be enabled
  */
 static void kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu)
 {
-	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
-	int i;
-
-	INIT_LIST_HEAD(&vgic_cpu->ap_list_head);
-	spin_lock_init(&vgic_cpu->ap_list_lock);
-
-	/*
-	 * Enable and configure all SGIs to be edge-triggered and
-	 * configure all PPIs as level-triggered.
-	 */
-	for (i = 0; i < VGIC_NR_PRIVATE_IRQS; i++) {
-		struct vgic_irq *irq = &vgic_cpu->private_irqs[i];
-
-		INIT_LIST_HEAD(&irq->ap_list);
-		spin_lock_init(&irq->irq_lock);
-		irq->intid = i;
-		irq->vcpu = NULL;
-		irq->target_vcpu = vcpu;
-		irq->targets = 1U << vcpu->vcpu_id;
-		kref_init(&irq->refcount);
-		if (vgic_irq_is_sgi(i)) {
-			/* SGIs */
-			irq->enabled = 1;
-			irq->config = VGIC_CONFIG_EDGE;
-		} else {
-			/* PPIs */
-			irq->config = VGIC_CONFIG_LEVEL;
-		}
-	}
 	if (kvm_vgic_global_state.type == VGIC_V2)
 		vgic_v2_enable(vcpu);
 	else
-- 
2.9.0

[PATCH v2 09/10] KVM: arm/arm64: vgic: Don't check vgic_initialized in sync/flush

[Christoffer Dall]

Now when we do an early init of the static parts of the VGIC data
structures, we can do things like checking if the AP lists are empty
directly without having to explicitly check if the vgic is initialized
and reduce a bit of work in our critical path.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
---
Changes since v1:
 - Moved note about checking list_empty to other patch commit message
 - Removed check in both sync/flush in this patch

 virt/kvm/arm/vgic/vgic.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index b64b143..04a405a 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -633,9 +633,6 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
 {
 	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
 
-	if (unlikely(!vgic_initialized(vcpu->kvm)))
-		return;
-
 	vgic_fold_lr_state(vcpu);
 	vgic_prune_ap_list(vcpu);
 
@@ -646,9 +643,6 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
 /* Flush our emulation state into the GIC hardware before entering the guest. */
 void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
 {
-	if (unlikely(!vgic_initialized(vcpu->kvm)))
-		return;
-
 	/*
 	 * If there are no virtual interrupts active or pending for this
 	 * VCPU, then there is no work to do and we can bail out without
-- 
2.9.0

[PATCH v2 10/10] KVM: arm/arm64: vgic: Improve sync_hwstate performance

[Christoffer Dall]

There is no need to call any functions to fold LRs when we don't use any
LRs and we don't need to mess with overflow flags, take spinlocks, or
prune the AP list if the AP list is empty.

Note: list_empty is a single atomic read (uses READ_ONCE) and can
therefore check if a list is empty or not without the need to take the
spinlock protecting the list.

Signed-off-by: Christoffer Dall <cdall@linaro.org>
---
Changes since v1:
 - Moved clearing used_lrs into fold_lr_state
 - Moved hunk that removes check for vgic_initialized into previous
   patch

 virt/kvm/arm/vgic/vgic-v2.c |  7 +++++--
 virt/kvm/arm/vgic/vgic-v3.c |  7 +++++--
 virt/kvm/arm/vgic/vgic.c    | 10 ++++++----
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-v2.c b/virt/kvm/arm/vgic/vgic-v2.c
index f9c4329..a1fc07a 100644
--- a/virt/kvm/arm/vgic/vgic-v2.c
+++ b/virt/kvm/arm/vgic/vgic-v2.c
@@ -59,12 +59,13 @@ static bool lr_signals_eoi_mi(u32 lr_val)
  */
 void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu)
 {
-	struct vgic_v2_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v2;
+	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+	struct vgic_v2_cpu_if *cpuif = &vgic_cpu->vgic_v2;
 	int lr;
 
 	cpuif->vgic_hcr &= ~GICH_HCR_UIE;
 
-	for (lr = 0; lr < vcpu->arch.vgic_cpu.used_lrs; lr++) {
+	for (lr = 0; lr < vgic_cpu->used_lrs; lr++) {
 		u32 val = cpuif->vgic_lr[lr];
 		u32 intid = val & GICH_LR_VIRTUALID;
 		struct vgic_irq *irq;
@@ -106,6 +107,8 @@ void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu)
 		spin_unlock(&irq->irq_lock);
 		vgic_put_irq(vcpu->kvm, irq);
 	}
+
+	vgic_cpu->used_lrs = 0;
 }
 
 /*
diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index c7ac9b1..2bcee2e 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -36,13 +36,14 @@ static bool lr_signals_eoi_mi(u64 lr_val)
 
 void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu)
 {
-	struct vgic_v3_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v3;
+	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+	struct vgic_v3_cpu_if *cpuif = &vgic_cpu->vgic_v3;
 	u32 model = vcpu->kvm->arch.vgic.vgic_model;
 	int lr;
 
 	cpuif->vgic_hcr &= ~ICH_HCR_UIE;
 
-	for (lr = 0; lr < vcpu->arch.vgic_cpu.used_lrs; lr++) {
+	for (lr = 0; lr < vgic_cpu->used_lrs; lr++) {
 		u64 val = cpuif->vgic_lr[lr];
 		u32 intid;
 		struct vgic_irq *irq;
@@ -92,6 +93,8 @@ void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu)
 		spin_unlock(&irq->irq_lock);
 		vgic_put_irq(vcpu->kvm, irq);
 	}
+
+	vgic_cpu->used_lrs = 0;
 }
 
 /* Requires the irq to be locked already */
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 04a405a..3d0979c 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -633,11 +633,13 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
 {
 	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
 
-	vgic_fold_lr_state(vcpu);
-	vgic_prune_ap_list(vcpu);
+	/* An empty ap_list_head implies used_lrs == 0 */
+	if (list_empty(&vcpu->arch.vgic_cpu.ap_list_head))
+		return;
 
-	/* Make sure we can fast-path in flush_hwstate */
-	vgic_cpu->used_lrs = 0;
+	if (vgic_cpu->used_lrs)
+		vgic_fold_lr_state(vcpu);
+	vgic_prune_ap_list(vcpu);
 }
 
 /* Flush our emulation state into the GIC hardware before entering the guest. */
-- 
2.9.0

[PATCH v2 01/10] KVM: arm/arm64: vgic: Defer touching GICH_VMCR to vcpu_load/put

[Marc Zyngier]

On 21/03/17 21:10, Christoffer Dall wrote:
> From: Christoffer Dall <cdall@cs.columbia.edu>
> 
> We don't have to save/restore the VMCR on every entry to/from the guest,
> since on GICv2 we can access the control interface from EL1 and on VHE
> systems with GICv3 we can access the control interface from KVM running
> in EL2.
> 
> GICv3 systems without VHE become the rare case, which have to
> save/restore the register in the put/load functions by doing an extra
> jump to EL2 to access the EL2-only register state.
> 
> Note that userspace accesses may see out-of-date values if the VCPU is
> running while accessing the VGIC state via the KVM device API, but this
> is already the case and it is up to userspace to quiesce the CPUs before
> reading the CPU registers from the GIC for an up-to-date view.
> 
> Signed-off-by: Christoffer Dall <cdall@cs.columbia.edu>
> Signed-off-by: Christoffer Dall <cdall@linaro.org>

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

	M.
-- 
Jazz is not dead. It just smells funny...

[PATCH v2 02/10] KVM: arm/arm64: vgic: Avoid flushing vgic state when there's no pending IRQ

[Marc Zyngier]

On 21/03/17 21:10, Christoffer Dall wrote:
> From: Shih-Wei Li <shihwei@cs.columbia.edu>
> 
> We do not need to flush vgic states in each world switch unless
> there is pending IRQ queued to the vgic's ap list. We can thus reduce
> the overhead by not grabbing the spinlock and not making the extra
> function call to vgic_flush_lr_state.
> 
> Note: list_empty is a single atomic read (uses READ_ONCE) and can
> therefore check if a list is empty or not without the need to take the
> spinlock protecting the list.
> 
> Signed-off-by: Shih-Wei Li <shihwei@cs.columbia.edu>
> Signed-off-by: Christoffer Dall <cdall@linaro.org>

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

	M.
-- 
Jazz is not dead. It just smells funny...

[PATCH v2 04/10] KVM: arm/arm64: vgic: Only set underflow when actually out of LRs

[Marc Zyngier]

On 21/03/17 21:10, Christoffer Dall wrote:
> We currently assume that all the interrupts in our AP list will be
> queued to LRs, but that's not necessarily the case, because some of them
> could have been migrated away to different VCPUs and only the VCPU
> thread itself can remove interrupts from its AP list.
> 
> Therefore, slightly change the logic to only setting the underflow
> interrupt when we actually run out of LRs.
> 
> As it turns out, this allows us to further simplify the handling in
> vgic_sync_hwstate in later patches.
> 
> Signed-off-by: Christoffer Dall <cdall@linaro.org>

Acked-by: Marc Zyngier <marc.zyngier@arm.com>

	M.
-- 
Jazz is not dead. It just smells funny...

[PATCH v2 05/10] KVM: arm/arm64: vgic: Get rid of unnecessary process_maintenance operation

[Marc Zyngier]

On 21/03/17 21:10, Christoffer Dall wrote:
> From: Christoffer Dall <christoffer.dall@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
                                  ^^^
Typo.

> notifyfd when folding the LR state and save some cycles in the process.
> 
> We now clear the underflow bit in the fold_lr_state functions as we only
> need to clear this bit if we had used all the LRs, so this is as good a
> place as any to do that work.
> 
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

	M.
-- 
Jazz is not dead. It just smells funny...

[PATCH v2 10/10] KVM: arm/arm64: vgic: Improve sync_hwstate performance

[Marc Zyngier]

On 21/03/17 21:10, Christoffer Dall wrote:
> There is no need to call any functions to fold LRs when we don't use any
> LRs and we don't need to mess with overflow flags, take spinlocks, or
> prune the AP list if the AP list is empty.
> 
> Note: list_empty is a single atomic read (uses READ_ONCE) and can
> therefore check if a list is empty or not without the need to take the
> spinlock protecting the list.
> 
> Signed-off-by: Christoffer Dall <cdall@linaro.org>

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

	M.
-- 
Jazz is not dead. It just smells funny...