[Xen-devel] [PATCH v6 04/10] xen/arm: support HW interrupts, do not request maintenance_interrupts

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

If the irq to be injected is an hardware irq (p->desc != NULL), set
GICH_LR_HW. Do not set GICH_LR_MAINTENANCE_IRQ.

Remove the code to EOI a physical interrupt on behalf of the guest
because it has become unnecessary.

Introduce a new function, gic_clear_lrs, that goes over the GICH_LR
registers, clear the invalid ones and free the corresponding interrupts
from the inflight queue if appropriate. Add the interrupt to lr_pending
if the GIC_IRQ_GUEST_PENDING is still set.

Call gic_clear_lrs on entry to the hypervisor to make sure that the
calculation in Xen of the highest priority interrupt currently inflight
is correct and accurate and not based on stale data.

In vgic_vcpu_inject_irq, if the target is a vcpu running on another
pcpu, we are already sending an SGI to the other pcpu so that it would
pick up the new IRQ to inject.  Now also send an SGI to the other pcpu
even if the IRQ is already inflight, so that it can clear the LR
corresponding to the previous injection as well as injecting the new
interrupt.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

---

Changes in v6:
- remove double spin_lock on the vgic.lock introduced in v5.

Changes in v5:
- do not rename virtual_irq to irq;
- replace "const long unsigned int" with "const unsigned long";
- remove useless "& GICH_LR_PHYSICAL_MASK" in gic_set_lr;
- add a comment in maintenance_interrupts to explain its new purpose.
- introduce gic_clear_one_lr.

Changes in v4:
- merged patch #3 and #4 into a single patch.

Changes in v2:
- remove the EOI code, now unnecessary;
- do not assume physical IRQ == virtual IRQ;
- refactor gic_set_lr.
---
 xen/arch/arm/gic.c        |  137 +++++++++++++++++++++------------------------
 xen/arch/arm/traps.c      |   10 ++++
 xen/arch/arm/vgic.c       |    3 +-
 xen/include/asm-arm/gic.h |    1 +
 4 files changed, 76 insertions(+), 75 deletions(-)

diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index a7b29d8..e1165e3 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -68,6 +68,8 @@ static DEFINE_PER_CPU(u8, gic_cpu_id);
 /* Maximum cpu interface per GIC */
 #define NR_GIC_CPU_IF 8
 
+static void gic_clear_one_lr(struct vcpu *v, int i);
+
 static unsigned int gic_cpu_mask(const cpumask_t *cpumask)
 {
     unsigned int cpu;
@@ -626,16 +628,18 @@ int __init setup_dt_irq(const struct dt_irq *irq, struct 
irqaction *new)
 static inline void gic_set_lr(int lr, struct pending_irq *p,
         unsigned int state)
 {
-    int maintenance_int = GICH_LR_MAINTENANCE_IRQ;
+    uint32_t lr_reg;
 
     BUG_ON(lr >= nr_lrs);
     BUG_ON(lr < 0);
     BUG_ON(state & ~(GICH_LR_STATE_MASK<<GICH_LR_STATE_SHIFT));
 
-    GICH[GICH_LR + lr] = state |
-        maintenance_int |
-        ((p->priority >> 3) << GICH_LR_PRIORITY_SHIFT) |
+    lr_reg = state | ((p->priority >> 3) << GICH_LR_PRIORITY_SHIFT) |
         ((p->irq & GICH_LR_VIRTUAL_MASK) << GICH_LR_VIRTUAL_SHIFT);
+    if ( p->desc != NULL )
+        lr_reg |= GICH_LR_HW | (p->desc->irq << GICH_LR_PHYSICAL_SHIFT);
+
+    GICH[GICH_LR + lr] = lr_reg;
 
     set_bit(GIC_IRQ_GUEST_VISIBLE, &p->status);
     clear_bit(GIC_IRQ_GUEST_PENDING, &p->status);
@@ -695,6 +699,56 @@ out:
     return;
 }
 
+static void gic_clear_one_lr(struct vcpu *v, int i)
+{
+    struct pending_irq *p;
+    uint32_t lr;
+    int irq;
+    bool_t inflight;
+
+    ASSERT(spin_is_locked(&v->arch.vgic.lock));
+
+    lr = GICH[GICH_LR + i];
+    if ( !(lr & (GICH_LR_PENDING|GICH_LR_ACTIVE)) )
+    {
+        inflight = 0;
+        GICH[GICH_LR + i] = 0;
+        clear_bit(i, &this_cpu(lr_mask));
+
+        irq = (lr >> GICH_LR_VIRTUAL_SHIFT) & GICH_LR_VIRTUAL_MASK;
+        spin_lock(&gic.lock);
+        p = irq_to_pending(v, irq);
+        if ( p->desc != NULL )
+            p->desc->status &= ~IRQ_INPROGRESS;
+        clear_bit(GIC_IRQ_GUEST_VISIBLE, &p->status);
+        if ( test_bit(GIC_IRQ_GUEST_PENDING, &p->status) &&
+                test_bit(GIC_IRQ_GUEST_ENABLED, &p->status))
+        {
+            inflight = 1;
+            gic_set_guest_irq(v, irq, GICH_LR_PENDING, p->priority);
+        }
+        spin_unlock(&gic.lock);
+        if ( !inflight )
+            list_del_init(&p->inflight);
+    }
+}
+
+void gic_clear_lrs(struct vcpu *v)
+{
+    int i = 0;
+    unsigned long flags;
+
+    spin_lock_irqsave(&v->arch.vgic.lock, flags);
+
+    while ((i = find_next_bit((const unsigned long *) &this_cpu(lr_mask),
+                              nr_lrs, i)) < nr_lrs) {
+        gic_clear_one_lr(v, i);
+        i++;
+    }
+
+    spin_unlock_irqrestore(&v->arch.vgic.lock, flags);
+}
+
 static void gic_restore_pending_irqs(struct vcpu *v)
 {
     int i;
@@ -893,77 +947,14 @@ int gicv_setup(struct domain *d)
 
 }
 
-static void gic_irq_eoi(void *info)
-{
-    int virq = (uintptr_t) info;
-    GICC[GICC_DIR] = virq;
-}
-
 static void maintenance_interrupt(int irq, void *dev_id, struct cpu_user_regs 
*regs)
 {
-    int i = 0, virq, pirq = -1;
-    uint32_t lr;
-    struct vcpu *v = current;
-    uint64_t eisr = GICH[GICH_EISR0] | (((uint64_t) GICH[GICH_EISR1]) << 32);
-
-    while ((i = find_next_bit((const long unsigned int *) &eisr,
-                              64, i)) < 64) {
-        struct pending_irq *p, *p2;
-        int cpu;
-        bool_t inflight;
-
-        cpu = -1;
-        inflight = 0;
-
-        spin_lock_irq(&gic.lock);
-        lr = GICH[GICH_LR + i];
-        virq = lr & GICH_LR_VIRTUAL_MASK;
-        GICH[GICH_LR + i] = 0;
-        clear_bit(i, &this_cpu(lr_mask));
-
-        p = irq_to_pending(v, virq);
-        if ( p->desc != NULL ) {
-            p->desc->status &= ~IRQ_INPROGRESS;
-            /* Assume only one pcpu needs to EOI the irq */
-            cpu = p->desc->arch.eoi_cpu;
-            pirq = p->desc->irq;
-        }
-        if ( test_bit(GIC_IRQ_GUEST_PENDING, &p->status) &&
-             test_bit(GIC_IRQ_GUEST_ENABLED, &p->status))
-        {
-            inflight = 1;
-            gic_add_to_lr_pending(v, p);
-        }
-
-        clear_bit(GIC_IRQ_GUEST_VISIBLE, &p->status);
-
-        if ( !list_empty(&v->arch.vgic.lr_pending) ) {
-            p2 = list_entry(v->arch.vgic.lr_pending.next, typeof(*p2), 
lr_queue);
-            gic_set_lr(i, p2, GICH_LR_PENDING);
-            list_del_init(&p2->lr_queue);
-            set_bit(i, &this_cpu(lr_mask));
-        }
-        spin_unlock_irq(&gic.lock);
-
-        if ( !inflight )
-        {
-            spin_lock_irq(&v->arch.vgic.lock);
-            list_del_init(&p->inflight);
-            spin_unlock_irq(&v->arch.vgic.lock);
-        }
-
-        if ( p->desc != NULL ) {
-            /* this is not racy because we can't receive another irq of the
-             * same type until we EOI it.  */
-            if ( cpu == smp_processor_id() )
-                gic_irq_eoi((void*)(uintptr_t)pirq);
-            else
-                on_selected_cpus(cpumask_of(cpu),
-                                 gic_irq_eoi, (void*)(uintptr_t)pirq, 0);
-        }
-
-        i++;
-    }
+    /* 
+     * The maintenance interrupt handler doesn't do anything anymore, but
+     * receiving the interrupt is going to cause gic_inject to be called on
+     * return to guest that is going to clear the old LRs and inject new
+     * interrupts.
+     */
 }
 
 void gic_dump_info(struct vcpu *v)
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 21c7b26..dd936be 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -68,6 +68,7 @@ static int debug_stack_lines = 40;
 
 integer_param("debug_stack_lines", debug_stack_lines);
 
+static void enter_hypervisor_head(void);
 
 void __cpuinit init_traps(void)
 {
@@ -1543,6 +1544,8 @@ asmlinkage void do_trap_hypervisor(struct cpu_user_regs 
*regs)
 {
     union hsr hsr = { .bits = READ_SYSREG32(ESR_EL2) };
 
+    enter_hypervisor_head();
+
     switch (hsr.ec) {
     case HSR_EC_WFI_WFE:
         if ( !check_conditional_instr(regs, hsr) )
@@ -1620,11 +1623,13 @@ asmlinkage void do_trap_hypervisor(struct cpu_user_regs 
*regs)
 
 asmlinkage void do_trap_irq(struct cpu_user_regs *regs)
 {
+    enter_hypervisor_head();
     gic_interrupt(regs, 0);
 }
 
 asmlinkage void do_trap_fiq(struct cpu_user_regs *regs)
 {
+    enter_hypervisor_head();
     gic_interrupt(regs, 1);
 }
 
@@ -1642,6 +1647,11 @@ asmlinkage void leave_hypervisor_tail(void)
     }
 }
 
+static void enter_hypervisor_head(void)
+{
+    gic_clear_lrs(current);
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
index aab490c..566f0ff 100644
--- a/xen/arch/arm/vgic.c
+++ b/xen/arch/arm/vgic.c
@@ -701,8 +701,7 @@ void vgic_vcpu_inject_irq(struct vcpu *v, unsigned int irq)
         if ( (irq != current->domain->arch.evtchn_irq) ||
              (!test_bit(GIC_IRQ_GUEST_VISIBLE, &n->status)) )
             set_bit(GIC_IRQ_GUEST_PENDING, &n->status);
-        spin_unlock_irqrestore(&v->arch.vgic.lock, flags);
-        return;
+        goto out;
     }
 
     /* vcpu offline */
diff --git a/xen/include/asm-arm/gic.h b/xen/include/asm-arm/gic.h
index 6fce5c2..ebb90c6 100644
--- a/xen/include/asm-arm/gic.h
+++ b/xen/include/asm-arm/gic.h
@@ -220,6 +220,7 @@ extern unsigned int gic_number_lines(void);
 /* IRQ translation function for the device tree */
 int gic_irq_xlate(const u32 *intspec, unsigned int intsize,
                   unsigned int *out_hwirq, unsigned int *out_type);
+void gic_clear_lrs(struct vcpu *v);
 
 #endif /* __ASSEMBLY__ */
 #endif
-- 
1.7.10.4


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