ARM: new VGIC: Add ACTIVE registers handlers

The active register handlers are shared between the v2 and v3 emulation,
so their implementation goes into vgic-mmio.c, to be easily referenced
from the v3 emulation as well later.
Since activation/deactivation of an interrupt may happen entirely in the
guest without it ever exiting, we need some extra logic to properly track
the active state.
For clearing the active state, we would basically have to halt the guest
to make sure this is properly propagated into the respective VCPUs.
This is not yet implemented in Xen.
Fortunately this feature is mostly used to reset a just in initialised
GIC, so chances are we are tasked to clear bits that are already zero.
Add a simple check to avoid pointless warnings in this case.

Signed-off-by: Andre Przywara <andre.przywara@linaro.org>
Reviewed-by: Julien Grall <julien.grall@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>

diff --git a/xen/arch/arm/vgic/vgic-mmio-v2.c b/xen/arch/arm/vgic/vgic-mmio-v2.c
index d84f506063ded48298b444f562c6a34110ad9b58..2f5d590b34a0a28e0c05476bc3d55e8e107c7ab4 100644 (file)
--- a/xen/arch/arm/vgic/vgic-mmio-v2.c
+++ b/xen/arch/arm/vgic/vgic-mmio-v2.c
@@ -101,10 +101,10 @@ static const struct vgic_register_region vgic_v2_dist_registers[] = {
         vgic_mmio_read_pending, vgic_mmio_write_cpending, 1,
         VGIC_ACCESS_32bit),
     REGISTER_DESC_WITH_BITS_PER_IRQ(GICD_ISACTIVER,
-        vgic_mmio_read_raz, vgic_mmio_write_wi, 1,
+        vgic_mmio_read_active, vgic_mmio_write_sactive, 1,
         VGIC_ACCESS_32bit),
     REGISTER_DESC_WITH_BITS_PER_IRQ(GICD_ICACTIVER,
-        vgic_mmio_read_raz, vgic_mmio_write_wi, 1,
+        vgic_mmio_read_active, vgic_mmio_write_cactive, 1,
         VGIC_ACCESS_32bit),
     REGISTER_DESC_WITH_BITS_PER_IRQ(GICD_IPRIORITYR,
         vgic_mmio_read_raz, vgic_mmio_write_wi, 8,

diff --git a/xen/arch/arm/vgic/vgic-mmio.c b/xen/arch/arm/vgic/vgic-mmio.c
index 7f9ff3ba57af50ba98f0e2c93abf36fc152fa7d7..5d4c599dcf64ed5269011403fc3fdea1a2a74b22 100644 (file)
--- a/xen/arch/arm/vgic/vgic-mmio.c
+++ b/xen/arch/arm/vgic/vgic-mmio.c
@@ -285,6 +285,97 @@ void vgic_mmio_write_cpending(struct vcpu *vcpu,
     }
 }
 
+/*
+ * The actual active bit for a virtual IRQ is held in the LR. Our shadow
+ * copy in struct vgic_irq is only synced when needed and may not be
+ * up-to-date all of the time.
+ * Returning the actual active state is quite costly (stopping all
+ * VCPUs processing any affected vIRQs), so we use a simple implementation
+ * to get the best possible answer.
+ */
+unsigned long vgic_mmio_read_active(struct vcpu *vcpu,
+                                    paddr_t addr, unsigned int len)
+{
+    uint32_t intid = VGIC_ADDR_TO_INTID(addr, 1);
+    uint32_t value = 0;
+    unsigned int i;
+
+    /* Loop over all IRQs affected by this read */
+    for ( i = 0; i < len * 8; i++ )
+    {
+        struct vgic_irq *irq = vgic_get_irq(vcpu->domain, vcpu, intid + i);
+
+        if ( irq->active )
+            value |= (1U << i);
+
+        vgic_put_irq(vcpu->domain, irq);
+    }
+
+    return value;
+}
+
+/*
+ * We don't actually support clearing the active state of an IRQ (yet).
+ * However there is a chance that most guests use this for initialization.
+ * We check whether this MMIO access would actually affect any active IRQ,
+ * and only print our warning in this case. So clearing already non-active
+ * IRQs would not be moaned about in the logs.
+ */
+void vgic_mmio_write_cactive(struct vcpu *vcpu,
+                             paddr_t addr, unsigned int len,
+                             unsigned long val)
+{
+    uint32_t intid = VGIC_ADDR_TO_INTID(addr, 1);
+    unsigned int i;
+
+    for_each_set_bit( i, &val, len * 8 )
+    {
+        struct vgic_irq *irq = vgic_get_irq(vcpu->domain, vcpu, intid + i);
+
+        /*
+         * If we know that the IRQ is active or we can't be sure about
+         * it (because it is currently in a CPU), log the not properly
+         * emulated MMIO access.
+         */
+        if ( irq->active || irq->vcpu )
+            printk(XENLOG_G_ERR
+                   "%pv: vGICD: IRQ%u: clearing active state not supported\n",
+                   vcpu, irq->intid);
+
+        vgic_put_irq(vcpu->domain, irq);
+    }
+}
+
+/*
+ * We don't actually support setting the active state of an IRQ (yet).
+ * We check whether this MMIO access would actually affect any non-active IRQ,
+ * and only print our warning in this case.
+ */
+void vgic_mmio_write_sactive(struct vcpu *vcpu,
+                             paddr_t addr, unsigned int len,
+                             unsigned long val)
+{
+    uint32_t intid = VGIC_ADDR_TO_INTID(addr, 1);
+    unsigned int i;
+
+    for_each_set_bit( i, &val, len * 8 )
+    {
+        struct vgic_irq *irq = vgic_get_irq(vcpu->domain, vcpu, intid + i);
+
+        /*
+         * If we know that the IRQ is not active or we can't be sure about
+         * it (because it is currently in a CPU), log the not properly
+         * emulated MMIO access.
+         */
+        if ( !irq->active || irq->vcpu )
+            printk(XENLOG_G_ERR
+                   "%pv: vGICD: IRQ%u: setting active state not supported\n",
+                   vcpu, irq->intid);
+
+        vgic_put_irq(vcpu->domain, irq);
+    }
+}
+
 static int match_region(const void *key, const void *elt)
 {
     const unsigned int offset = (unsigned long)key;

diff --git a/xen/arch/arm/vgic/vgic-mmio.h b/xen/arch/arm/vgic/vgic-mmio.h
index 5c927f28b05029bb6fb388abee7f7e3a6821b6fb..832e2eb3d84c6fad4929a020f16f8bd176c84087 100644 (file)
--- a/xen/arch/arm/vgic/vgic-mmio.h
+++ b/xen/arch/arm/vgic/vgic-mmio.h
@@ -108,6 +108,17 @@ void vgic_mmio_write_cpending(struct vcpu *vcpu,
                               paddr_t addr, unsigned int len,
                               unsigned long val);
 
+unsigned long vgic_mmio_read_active(struct vcpu *vcpu,
+                                    paddr_t addr, unsigned int len);
+
+void vgic_mmio_write_cactive(struct vcpu *vcpu,
+                             paddr_t addr, unsigned int len,
+                             unsigned long val);
+
+void vgic_mmio_write_sactive(struct vcpu *vcpu,
+                             paddr_t addr, unsigned int len,
+                             unsigned long val);
+
 unsigned int vgic_v2_init_dist_iodev(struct vgic_io_device *dev);
 
 #endif