xen/arm: vgic: Use dynamic memory allocation for vgic_rdist_region

The number of Redistributor regions allowed for dom0 is hardcoded
to a define MAX_RDIST_COUNT which is 4. Some systems, especially
latest server chips, may have more than 4 redistributors. Either we
have to increase MAX_RDIST_COUNT to a bigger number or allocate
memory based on the number of redistributors that are found in MADT
table. In the worst case scenario, the macro MAX_RDIST_COUNT should
be equal to CONFIG_NR_CPUS in order to support per CPU Redistributors.

Increasing MAX_RDIST_COUNT has a effect, it blows 'struct domain'
size and hits BUILD_BUG_ON() in domain build code path.

struct domain *alloc_domain_struct(void)
{
    struct domain *d;
    BUILD_BUG_ON(sizeof(*d) > PAGE_SIZE);
    d = alloc_xenheap_pages(0, 0);
    if ( d == NULL )
        return NULL;
...

This patch uses the second approach to fix the BUILD_BUG().

Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org>
Reviewed-by: Julien Grall <julien.grall@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>

xen/arch/arm/vgic-v2.c

@@ -699,9 +699,15 @@ static int vgic_v2_domain_init(struct domain *d)
     return 0;
 }
 
+static void vgic_v2_domain_free(struct domain *d)
+{
+    /* Nothing to be cleanup for this driver */
+}
+
 static const struct vgic_ops vgic_v2_ops = {
     .vcpu_init   = vgic_v2_vcpu_init,
     .domain_init = vgic_v2_domain_init,
+    .domain_free = vgic_v2_domain_free,
     .max_vcpus = 8,
 };
 

xen/arch/arm/vgic-v3.c

@@ -1391,9 +1391,26 @@ static int vgic_v3_vcpu_init(struct vcpu *v)
     return 0;
 }
 
+static inline unsigned int vgic_v3_rdist_count(struct domain *d)
+{
+    return is_hardware_domain(d) ? vgic_v3_hw.nr_rdist_regions :
+               GUEST_GICV3_RDIST_REGIONS;
+}
+
 static int vgic_v3_domain_init(struct domain *d)
 {
-    int i;
+    struct vgic_rdist_region *rdist_regions;
+    int rdist_count, i;
+
+    /* Allocate memory for Re-distributor regions */
+    rdist_count = vgic_v3_rdist_count(d);
+
+    rdist_regions = xzalloc_array(struct vgic_rdist_region, rdist_count);
+    if ( !rdist_regions )
+        return -ENOMEM;
+
+    d->arch.vgic.nr_regions = rdist_count;
+    d->arch.vgic.rdist_regions = rdist_regions;
 
     /*
      * Domain 0 gets the hardware address.
@@ -1426,7 +1443,6 @@ static int vgic_v3_domain_init(struct domain *d)
 
             first_cpu += size / d->arch.vgic.rdist_stride;
         }
-        d->arch.vgic.nr_regions = vgic_v3_hw.nr_rdist_regions;
     }
     else
     {
@@ -1435,7 +1451,6 @@ static int vgic_v3_domain_init(struct domain *d)
         /* XXX: Only one Re-distributor region mapped for the guest */
         BUILD_BUG_ON(GUEST_GICV3_RDIST_REGIONS != 1);
 
-        d->arch.vgic.nr_regions = GUEST_GICV3_RDIST_REGIONS;
         d->arch.vgic.rdist_stride = GUEST_GICV3_RDIST_STRIDE;
 
         /* The first redistributor should contain enough space for all CPUs */
@@ -1467,9 +1482,15 @@ static int vgic_v3_domain_init(struct domain *d)
     return 0;
 }
 
+static void vgic_v3_domain_free(struct domain *d)
+{
+    xfree(d->arch.vgic.rdist_regions);
+}
+
 static const struct vgic_ops v3_ops = {
     .vcpu_init   = vgic_v3_vcpu_init,
     .domain_init = vgic_v3_domain_init,
+    .domain_free = vgic_v3_domain_free,
     .emulate_sysreg  = vgic_v3_emulate_sysreg,
     /*
      * We use both AFF1 and AFF0 in (v)MPIDR. Thus, the max number of CPU

xen/arch/arm/vgic.c

@@ -179,6 +179,7 @@ void domain_vgic_free(struct domain *d)
         }
     }
 
+    d->arch.vgic.handler->domain_free(d);
     xfree(d->arch.vgic.shared_irqs);
     xfree(d->arch.vgic.pending_irqs);
     xfree(d->arch.vgic.allocated_irqs);

xen/include/asm-arm/domain.h

@@ -107,7 +107,7 @@ struct arch_domain
             paddr_t base;                   /* Base address */
             paddr_t size;                   /* Size */
             unsigned int first_cpu;         /* First CPU handled */
-        } rdist_regions[MAX_RDIST_COUNT];
+        } *rdist_regions;
         int nr_regions;                     /* Number of rdist regions */
         uint32_t rdist_stride;              /* Re-Distributor stride */
 #endif

xen/include/asm-arm/vgic.h

@@ -128,6 +128,8 @@ struct vgic_ops {
     int (*vcpu_init)(struct vcpu *v);
     /* Domain specific initialization of vGIC */
     int (*domain_init)(struct domain *d);
+    /* Release resources that were allocated by domain_init */
+    void (*domain_free)(struct domain *d);
     /* vGIC sysreg emulation */
     int (*emulate_sysreg)(struct cpu_user_regs *regs, union hsr hsr);
     /* Maximum number of vCPU supported */