[Xen-devel] [PATCH v7 7/8] xen/arm: make domain_max_vcpus return value from vgic_ops

[Chen Baozi <cbz@xxxxxxxxxx>]

From: Chen Baozi <baozich@xxxxxxxxx>

When a guest uses vGICv2, the maximum number of vCPU it can support
should not be as many as MAX_VIRT_CPUS, which will be more than 8
when GICv3 is used on arm64. So the domain_max_vcpus should return
the value according to the vGIC the domain uses.

We didn't keep it as the old static inline form because it will break
compilation when access the member of struct domain:

In file included from xen/include/xen/domain.h:6:0,
                 from xen/include/xen/sched.h:10,
                 from arm64/asm-offsets.c:10:
xen/include/asm/domain.h: In function âdomain_max_vcpusâ:
xen/include/asm/domain.h:266:10: error: dereferencing pointer to incomplete type
     if (d->arch.vgic.version == GIC_V2)
          ^

Signed-off-by: Chen Baozi <baozich@xxxxxxxxx>
---
 xen/arch/arm/domain.c        | 9 +++++++++
 xen/arch/arm/vgic-v2.c       | 1 +
 xen/arch/arm/vgic-v3.c       | 7 +++++++
 xen/include/asm-arm/domain.h | 5 +----
 xen/include/asm-arm/vgic.h   | 2 ++
 5 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 0cf147c..df71a60 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -890,6 +890,15 @@ void vcpu_block_unless_event_pending(struct vcpu *v)
         vcpu_unblock(current);
 }
 
+unsigned int domain_max_vcpus(const struct domain *d)
+{
+    if ( !d->arch.vgic.handler )
+        return MAX_VIRT_CPUS;
+    else
+        return min_t(unsigned int, MAX_VIRT_CPUS,
+                     d->arch.vgic.handler->max_vcpus);
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/arm/vgic-v2.c b/xen/arch/arm/vgic-v2.c
index 5949cf1..bbeb740 100644
--- a/xen/arch/arm/vgic-v2.c
+++ b/xen/arch/arm/vgic-v2.c
@@ -585,6 +585,7 @@ const struct vgic_ops vgic_v2_ops = {
     .domain_init = vgic_v2_domain_init,
     .get_irq_priority = vgic_v2_get_irq_priority,
     .get_target_vcpu = vgic_v2_get_target_vcpu,
+    .max_vcpus = 8,
 };
 
 /*
diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
index 93610d0..417729b 100644
--- a/xen/arch/arm/vgic-v3.c
+++ b/xen/arch/arm/vgic-v3.c
@@ -32,6 +32,12 @@
 #include <asm/gic.h>
 #include <asm/vgic.h>
 
+/*
+ * We will use both AFF1 and AFF0 in (v)MPIDR. Thus, the max number of CPU
+ * that can be supported is up to 4096(256*16) in theory.
+ */
+#define GICV3_MAX_CPUS  4096
+
 /* GICD_PIDRn register values for ARM implementations */
 #define GICV3_GICD_PIDR0  0x92
 #define GICV3_GICD_PIDR1  0xb4
@@ -1204,6 +1210,7 @@ const struct vgic_ops vgic_v3_ops = {
     .get_irq_priority = vgic_v3_get_irq_priority,
     .get_target_vcpu  = vgic_v3_get_target_vcpu,
     .emulate_sysreg  = vgic_v3_emulate_sysreg,
+    .max_vcpus = GICV3_MAX_CPUS,
 };
 
 /*
diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
index 35b9a6d..23598dd 100644
--- a/xen/include/asm-arm/domain.h
+++ b/xen/include/asm-arm/domain.h
@@ -261,10 +261,7 @@ struct arch_vcpu
 void vcpu_show_execution_state(struct vcpu *);
 void vcpu_show_registers(const struct vcpu *);
 
-static inline unsigned int domain_max_vcpus(const struct domain *d)
-{
-    return MAX_VIRT_CPUS;
-}
+unsigned int domain_max_vcpus(const struct domain *);
 
 /*
  * Due to the restriction of GICv3, the number of vCPUs in AFF0 is
diff --git a/xen/include/asm-arm/vgic.h b/xen/include/asm-arm/vgic.h
index cc68c27..419e767 100644
--- a/xen/include/asm-arm/vgic.h
+++ b/xen/include/asm-arm/vgic.h
@@ -117,6 +117,8 @@ struct vgic_ops {
     struct vcpu *(*get_target_vcpu)(struct vcpu *v, unsigned int irq);
     /* vGIC sysreg emulation */
     int (*emulate_sysreg)(struct cpu_user_regs *regs, union hsr hsr);
+    /* Maximum number of vCPU supported */
+    const unsigned int max_vcpus;
 };
 
 /* Number of ranks of interrupt registers for a domain */
-- 
2.1.4


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