[PATCH v5 08/19] arm/arm64: KVM: make the maximum number of vCPUs a per-VM value
Andre Przywara
andre.przywara at arm.com
Mon Dec 8 04:37:43 PST 2014
Currently the maximum number of vCPUs supported is a global value
limited by the used GIC model. GICv3 will lift this limit, but we
still need to observe it for guests using GICv2.
So the maximum number of vCPUs is per-VM value, depending on the
GIC model the guest uses.
Store and check the value in struct kvm_arch, but keep it down to
8 for now.
Signed-off-by: Andre Przywara <andre.przywara at arm.com>
---
Changelog v4...v5:
- add define for GIC_V2_MAX_CPUS
- rename max_hw_vcpus
- add prototype for ARM non-VGIC configs
Changelog v3...v4:
- initialize max_vcpus with limit based on host GIC
- remove *_init_emul_* from VGIC backend
- refine VCPU limit on VGIC creation
- print warning when userland tries to create more VCPUs than supported
arch/arm/include/asm/kvm_host.h | 1 +
arch/arm/kvm/arm.c | 8 ++++++++
arch/arm64/include/asm/kvm_host.h | 3 +++
include/kvm/arm_vgic.h | 8 ++++++++
virt/kvm/arm/vgic-v2.c | 1 +
virt/kvm/arm/vgic-v3.c | 1 +
virt/kvm/arm/vgic.c | 22 ++++++++++++++++++++++
7 files changed, 44 insertions(+)
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index b443dfe..7969e6e 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -68,6 +68,7 @@ struct kvm_arch {
/* Interrupt controller */
struct vgic_dist vgic;
+ int max_vcpus;
};
#define KVM_NR_MEM_OBJS 40
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 8817fbd..c3d0fbd 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -132,6 +132,9 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
/* Mark the initial VMID generation invalid */
kvm->arch.vmid_gen = 0;
+ /* The maximum number of VCPUs is limited by the host's GIC model */
+ kvm->arch.max_vcpus = kvm_vgic_get_max_vcpus();
+
return ret;
out_free_stage2_pgd:
kvm_free_stage2_pgd(kvm);
@@ -213,6 +216,11 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
int err;
struct kvm_vcpu *vcpu;
+ if (id >= kvm->arch.max_vcpus) {
+ err = -EINVAL;
+ goto out;
+ }
+
vcpu = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL);
if (!vcpu) {
err = -ENOMEM;
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 286bb61..f9e130d 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -59,6 +59,9 @@ struct kvm_arch {
/* VTTBR value associated with above pgd and vmid */
u64 vttbr;
+ /* The maximum number of vCPUs depends on the used GIC model */
+ int max_vcpus;
+
/* Interrupt controller */
struct vgic_dist vgic;
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index e691932..72a9fef 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -33,6 +33,7 @@
#define VGIC_V2_MAX_LRS (1 << 6)
#define VGIC_V3_MAX_LRS 16
#define VGIC_MAX_IRQS 1024
+#define VGIC_V2_MAX_CPUS 8
/* Sanity checks... */
#if (KVM_MAX_VCPUS > 8)
@@ -132,6 +133,7 @@ struct vgic_params {
unsigned int maint_irq;
/* Virtual control interface base address */
void __iomem *vctrl_base;
+ int max_gic_vcpus;
};
struct vgic_vm_ops {
@@ -288,6 +290,7 @@ struct kvm_exit_mmio;
#ifdef CONFIG_KVM_ARM_VGIC
int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write);
int kvm_vgic_hyp_init(void);
+int kvm_vgic_get_max_vcpus(void);
int kvm_vgic_init(struct kvm *kvm);
int kvm_vgic_create(struct kvm *kvm, u32 type);
void kvm_vgic_destroy(struct kvm *kvm);
@@ -387,6 +390,11 @@ static inline bool vgic_initialized(struct kvm *kvm)
{
return true;
}
+
+static inline int kvm_vgic_get_max_vcpus(void)
+{
+ return KVM_MAX_VCPUS;
+}
#endif
#endif
diff --git a/virt/kvm/arm/vgic-v2.c b/virt/kvm/arm/vgic-v2.c
index e1cd3cb..e8b82b2 100644
--- a/virt/kvm/arm/vgic-v2.c
+++ b/virt/kvm/arm/vgic-v2.c
@@ -237,6 +237,7 @@ int vgic_v2_probe(struct device_node *vgic_node,
vctrl_res.start, vgic->maint_irq);
vgic->type = VGIC_V2;
+ vgic->max_gic_vcpus = VGIC_V2_MAX_CPUS;
*ops = &vgic_v2_ops;
*params = vgic;
goto out;
diff --git a/virt/kvm/arm/vgic-v3.c b/virt/kvm/arm/vgic-v3.c
index d14c75f..ea39bad 100644
--- a/virt/kvm/arm/vgic-v3.c
+++ b/virt/kvm/arm/vgic-v3.c
@@ -235,6 +235,7 @@ int vgic_v3_probe(struct device_node *vgic_node,
vgic->vcpu_base = vcpu_res.start;
vgic->vctrl_base = NULL;
vgic->type = VGIC_V3;
+ vgic->max_gic_vcpus = KVM_MAX_VCPUS;
kvm_info("%s@%llx IRQ%d\n", vgic_node->name,
vcpu_res.start, vgic->maint_irq);
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index c481362..dcdbae5 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1848,6 +1848,17 @@ static int vgic_vcpu_init_maps(struct kvm_vcpu *vcpu, int nr_irqs)
}
/**
+ * kvm_vgic_get_max_vcpus - Get the maximum number of VCPUs allowed by HW
+ *
+ * The host's GIC naturally limits the maximum amount of VCPUs a guest
+ * can use.
+ */
+int kvm_vgic_get_max_vcpus(void)
+{
+ return vgic->max_gic_vcpus;
+}
+
+/**
* kvm_vgic_vcpu_init - Initialize per-vcpu VGIC state
* @vcpu: pointer to the vcpu struct
*
@@ -2069,6 +2080,8 @@ static int vgic_v2_init_emulation(struct kvm *kvm)
dist->vm_ops.vgic_init = vgic_v2_init;
dist->vm_ops.vgic_init_maps = vgic_v2_init_maps;
+ kvm->arch.max_vcpus = VGIC_V2_MAX_CPUS;
+
return 0;
}
@@ -2085,6 +2098,15 @@ static int init_vgic_model(struct kvm *kvm, int type)
break;
}
+ if (ret)
+ return ret;
+
+ if (atomic_read(&kvm->online_vcpus) > kvm->arch.max_vcpus) {
+ pr_warn_ratelimited("VGIC model only supports up to %d vCPUs\n",
+ kvm->arch.max_vcpus);
+ ret = -EINVAL;
+ }
+
return ret;
}
--
1.7.9.5
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