On Mon, Sep 16, 2013 at 09:09:27AM +0100, Marc Zyngier wrote: > On 15/09/13 10:30, Gleb Natapov wrote: > > On Sat, Sep 14, 2013 at 02:10:55PM +0200, Andrew Jones wrote: > >> Drop the _ARM_ part of the name. We can then introduce a config option > >> like this to aarch64 and other arches using the same name - allowing > >> grep to show them all. Also update the help text to describe the option > >> more completely. > >> > >> Signed-off-by: Andrew Jones <drjones@xxxxxxxxxx> > >> --- > >> arch/arm/include/asm/kvm_host.h | 4 ++-- > >> arch/arm/kvm/Kconfig | 8 ++++---- > >> 2 files changed, 6 insertions(+), 6 deletions(-) > >> > >> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h > >> index 7d22517d80711..c614d3eb176c6 100644 > >> --- a/arch/arm/include/asm/kvm_host.h > >> +++ b/arch/arm/include/asm/kvm_host.h > >> @@ -25,8 +25,8 @@ > >> #include <asm/fpstate.h> > >> #include <kvm/arm_arch_timer.h> > >> > >> -#if defined(CONFIG_KVM_ARM_MAX_VCPUS) > >> -#define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS > >> +#if defined(CONFIG_KVM_MAX_VCPUS) > >> +#define KVM_MAX_VCPUS CONFIG_KVM_MAX_VCPUS > >> #else > >> #define KVM_MAX_VCPUS 0 > >> #endif > >> diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig > >> index ebf5015508b52..de63bfccb3eb5 100644 > >> --- a/arch/arm/kvm/Kconfig > >> +++ b/arch/arm/kvm/Kconfig > >> @@ -40,16 +40,16 @@ config KVM_ARM_HOST > >> ---help--- > >> Provides host support for ARM processors. > >> > >> -config KVM_ARM_MAX_VCPUS > >> +config KVM_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. > > I do no see why on ARM vcpu structure size depends on KVM_ARM_MAX_VCPUS. > > Can somebody point me to it. > > There's a number of indirections, but here you go: > arch/arm/include/asm/kvm_host.h:#define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS > > include/kvm/arm_vgic.h:#define VGIC_MAX_CPUS KVM_MAX_VCPUS > > include/kvm/arm_vgic.h:#if (VGIC_MAX_CPUS > 8) > include/kvm/arm_vgic.h: } percpu[VGIC_MAX_CPUS]; > include/kvm/arm_vgic.h: u32 percpu[VGIC_MAX_CPUS][VGIC_NR_PRIVATE_IRQS / 4]; > include/kvm/arm_vgic.h: u8 irq_sgi_sources[VGIC_MAX_CPUS][VGIC_NR_SGIS]; > include/kvm/arm_vgic.h: struct vgic_bitmap irq_spi_target[VGIC_MAX_CPUS]; > > Basically, the GIC emulation data structures are sized on the number of VCPUs > (as well as the number of supported interrupts). > But vgic is per VM though, not per cpu as far as I can see, so the overhead is also per VM, no? Is VGIC_MAX_CPUS limit architectural or juts an implementation detail? -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
