Introduce CONFIG_KVM_ARM_MAX_VCPUS which defines the maximum number of
supported virtual CPUs per VMs on KVM/ARM. We don't want this number to
be arbitrarily large as it will take up a large amount of allocated VCPU
space for the VGIC structures for each VM. On the other hand we want to
run decent SMP VMs, and even 4 cores was until recently quite a lot on
an ARM machine, but this number is growing and for stress testing
purposes we want kernels that support more than 4 cpus, thus base the
limit on a config option.
Dynamically allocating the VGIC structures based on the number of VCPUS
will make the code even more difficult to read and understand.
Signed-off-by: Christoffer Dall <c.dall@xxxxxxxxxxxxxxxxxxxxxx>
---
arch/arm/include/asm/kvm_host.h | 2 +-
arch/arm/kvm/Kconfig | 11 +++++++++++
2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 7127fe7..6c1c6fc 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -25,7 +25,7 @@
#include <asm/kvm_vgic.h>
#include <asm/kvm_arch_timer.h>
-#define KVM_MAX_VCPUS NR_CPUS
+#define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS
#define KVM_MEMORY_SLOTS 32
#define KVM_PRIVATE_MEM_SLOTS 4
#define KVM_COALESCED_MMIO_PAGE_OFFSET 1
diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
index ade2673..eaecb9f 100644
--- a/arch/arm/kvm/Kconfig
+++ b/arch/arm/kvm/Kconfig
@@ -40,6 +40,17 @@ config KVM_ARM_HOST
---help---
Provides host support for ARM processors.
+config KVM_ARM_MAX_VCPUS
+ int "Number maximum supported virtual CPUs per VM"
+ depends on KVM_ARM_HOST
+ default 4
+ help
+ Static number of max supported virtual CPUs per VM.
+
+ If you choose a high number, the vcpu structures will be quite
+ large, so only choose a reasonable number that you expect to
+ actually use.
+
config KVM_ARM_VGIC
bool "KVM support for Virtual GIC"
depends on KVM_ARM_HOST && OF
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