[Xen-devel] [PATCH v2 2/3] xen/arm: vgic: Keep track of vIRQ used by a domain

[Julien Grall <julien.grall@xxxxxxxxxx>]

While it's easy to know which hardware IRQ is assigned to a domain, there
is no way to know which vIRQ is allocated by Xen for a specific domain.

Introduce a bitmap to keep track of every vIRQ used by a domain. This
will be used later to find free vIRQ for interrupt device assignment and
emulated interrupt.

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

---
    Changes in v2:
        - Remove lock
        - Update the prototype of vgic_free_irq to actually show we are
        taking in parameter a vIRQ and and IRQ
        - vgic_free_virq was completely buggy. Rewrite it
        - The usage of find_next_zero_bit was buggy. I don't know how it
        was working before.
        - Make find_next_zero_bit common for SPIs and PPIs
        - Use if (...) BUG() rather than BUG_ON()
        - Fix comments and some printk message
        - Update the commit message
        - Add missing vgic_reserve_irq for the event channel PPI
---
 xen/arch/arm/domain.c                |  3 ++
 xen/arch/arm/domain_build.c          |  6 ++++
 xen/arch/arm/platforms/xgene-storm.c |  4 +++
 xen/arch/arm/vgic.c                  | 58 ++++++++++++++++++++++++++++++++++++
 xen/arch/arm/vtimer.c                | 25 ++++++++++++++++
 xen/include/asm-arm/domain.h         |  1 +
 xen/include/asm-arm/vgic.h           | 13 ++++++++
 7 files changed, 110 insertions(+)

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 7221bc8..d0229d1 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -548,6 +548,9 @@ int arch_domain_create(struct domain *d, unsigned int 
domcr_flags)
     else
         d->arch.evtchn_irq = platform_dom0_evtchn_ppi();
 
+    if ( !vgic_reserve_virq(d, d->arch.evtchn_irq) )
+        BUG();
+
     /*
      * Virtual UART is only used by linux early printk and decompress code.
      * Only use it for the hardware domain because the linux kernel may not
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index c2dcb49..3d4f317 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -970,6 +970,12 @@ static int map_device(struct domain *d, struct 
dt_device_node *dev)
         irq = res;
 
         DPRINT("irq %u = %u\n", i, irq);
+        /*
+         * Checking the return of vgic_reserve_virq is not
+         * necessary. It should not fail except when we try to map
+         * twice the IRQ. This can happen if the IRQ is shared
+         */
+        vgic_reserve_virq(d, irq);
         res = route_irq_to_guest(d, irq, dt_node_name(dev));
         if ( res )
         {
diff --git a/xen/arch/arm/platforms/xgene-storm.c 
b/xen/arch/arm/platforms/xgene-storm.c
index 0b3492d..ef3ba63 100644
--- a/xen/arch/arm/platforms/xgene-storm.c
+++ b/xen/arch/arm/platforms/xgene-storm.c
@@ -71,6 +71,10 @@ static int map_one_spi(struct domain *d, const char *what,
 
     printk("Additional IRQ %u (%s)\n", irq, what);
 
+    if ( !vgic_reserve_virq(d, irq) )
+        printk("Failed to reserve vIRQ %u on dom%d\n",
+               irq, d->domain_id);
+
     ret = route_irq_to_guest(d, irq, what);
     if ( ret )
         printk("Failed to route %s to dom%d\n", what, d->domain_id);
diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
index b272d86..1a8b3cd 100644
--- a/xen/arch/arm/vgic.c
+++ b/xen/arch/arm/vgic.c
@@ -110,6 +110,15 @@ int domain_vgic_init(struct domain *d)
 
     d->arch.vgic.handler->domain_init(d);
 
+    d->arch.vgic.allocated_irqs =
+        xzalloc_array(unsigned long, BITS_TO_LONGS(vgic_num_irqs(d)));
+    if ( !d->arch.vgic.allocated_irqs )
+        return -ENOMEM;
+
+    /* vIRQ0-15 (SGIs) are reserved */
+    for ( i = 0; i <= 15; i++ )
+        set_bit(i, d->arch.vgic.allocated_irqs);
+
     return 0;
 }
 
@@ -122,6 +131,7 @@ void domain_vgic_free(struct domain *d)
 {
     xfree(d->arch.vgic.shared_irqs);
     xfree(d->arch.vgic.pending_irqs);
+    xfree(d->arch.vgic.allocated_irqs);
 }
 
 int vcpu_vgic_init(struct vcpu *v)
@@ -452,6 +462,54 @@ int vgic_emulate(struct cpu_user_regs *regs, union hsr hsr)
     return v->domain->arch.vgic.handler->emulate_sysreg(regs, hsr);
 }
 
+bool_t vgic_reserve_virq(struct domain *d, unsigned int virq)
+{
+    bool_t reserved;
+
+    if ( virq >= vgic_num_irqs(d) )
+        return 0;
+
+    reserved = !test_and_set_bit(virq, d->arch.vgic.allocated_irqs);
+
+    return reserved;
+}
+
+int vgic_allocate_virq(struct domain *d, bool_t spi)
+{
+    int ret;
+    int first, end;
+    unsigned int virq;
+
+retry:
+    if ( !spi )
+    {
+        /* We only allocate PPIs. SGIs are all reserved */
+        first = 16;
+        end = 32;
+    }
+    else
+    {
+        first = 32;
+        end = vgic_num_irqs(d);
+    }
+
+    virq = find_next_zero_bit(d->arch.vgic.allocated_irqs, end, first);
+    if ( virq >= end )
+        return -1;
+
+    ret = test_and_set_bit(virq, d->arch.vgic.allocated_irqs);
+
+    if ( unlikely(ret) )
+        goto retry;
+
+    return virq;
+}
+
+void vgic_free_virq(struct domain *d, unsigned int virq)
+{
+    clear_bit(virq, d->arch.vgic.allocated_irqs);
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/arm/vtimer.c b/xen/arch/arm/vtimer.c
index 848e2c6..4427ae5 100644
--- a/xen/arch/arm/vtimer.c
+++ b/xen/arch/arm/vtimer.c
@@ -56,6 +56,31 @@ int domain_vtimer_init(struct domain *d)
 {
     d->arch.phys_timer_base.offset = NOW();
     d->arch.virt_timer_base.offset = READ_SYSREG64(CNTPCT_EL0);
+
+    /* At this stage vgic_reserve_virq can't fail */
+    if ( is_hardware_domain(d) )
+    {
+        if ( !vgic_reserve_virq(d, timer_get_irq(TIMER_PHYS_SECURE_PPI)) )
+            BUG();
+
+        if ( !vgic_reserve_virq(d, timer_get_irq(TIMER_PHYS_NONSECURE_PPI)) )
+            BUG();
+
+        if ( !vgic_reserve_virq(d, timer_get_irq(TIMER_VIRT_PPI)) )
+            BUG();
+    }
+    else
+    {
+        if ( !vgic_reserve_virq(d, GUEST_TIMER_PHYS_S_PPI) )
+            BUG();
+
+        if ( !vgic_reserve_virq(d, GUEST_TIMER_PHYS_NS_PPI) )
+            BUG();
+
+        if ( !vgic_reserve_virq(d, GUEST_TIMER_VIRT_PPI) )
+            BUG();
+    }
+
     return 0;
 }
 
diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
index 8b7dd85..d302fc9 100644
--- a/xen/include/asm-arm/domain.h
+++ b/xen/include/asm-arm/domain.h
@@ -90,6 +90,7 @@ struct arch_domain
         spinlock_t lock;
         int ctlr;
         int nr_spis; /* Number of SPIs */
+        unsigned long *allocated_irqs; /* bitmap of IRQs allocated */
         struct vgic_irq_rank *shared_irqs;
         /*
          * SPIs are domain global, SGIs and PPIs are per-VCPU and stored in
diff --git a/xen/include/asm-arm/vgic.h b/xen/include/asm-arm/vgic.h
index 74d5a4e..5ddea51 100644
--- a/xen/include/asm-arm/vgic.h
+++ b/xen/include/asm-arm/vgic.h
@@ -199,6 +199,19 @@ extern int vgic_to_sgi(struct vcpu *v, register_t sgir,
                        enum gic_sgi_mode irqmode, int virq,
                        unsigned long vcpu_mask);
 extern void vgic_migrate_irq(struct vcpu *old, struct vcpu *new, unsigned int 
irq);
+
+/* Reserve a specific guest vIRQ */
+extern bool_t vgic_reserve_virq(struct domain *d, unsigned int virq);
+
+/*
+ * Allocate a guest VIRQ
+ *  - spi == 0 => allocate a PPI. It will be the same on every vCPU
+ *  - spi == 1 => allocate an SGI
+ */
+extern int vgic_allocate_virq(struct domain *d, bool_t spi);
+
+extern void vgic_free_virq(struct domain *d, unsigned int virq);
+
 #endif /* __ASM_ARM_VGIC_H__ */
 
 /*
-- 
2.1.4


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