On Sat, 2011-07-09 at 15:25 +0300, Sasha Levin wrote:
> The patch raises the hard limit of VCPU count to 1024.
>
> This will allow developers to easily work on scalability
> and will allow users to test high VCPU setups easily without
> patching the kernel.
>
> To prevent possible issues with current setups, KVM_CAP_NR_VCPUS
> now returns the recommended VCPU limit (which is still 64) - this
> should be a safe value for everybody, while a new KVM_CAP_MAX_VCPUS
> returns the hard limit which is now 1024.
>
> Cc: Avi Kivity <avi@xxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxx>
> Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
> Cc: Pekka Enberg <penberg@xxxxxxxxxx>
> Suggested-by: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
> Signed-off-by: Sasha Levin <levinsasha928@xxxxxxxxx>
> ---
Ping?
> Documentation/virtual/kvm/api.txt | 11 +++++++++--
> arch/x86/include/asm/kvm_host.h | 3 ++-
> arch/x86/kvm/x86.c | 3 +++
> include/linux/kvm.h | 3 ++-
> 4 files changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 42542eb..84883a0 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -175,10 +175,17 @@ Parameters: vcpu id (apic id on x86)
> Returns: vcpu fd on success, -1 on error
>
> This API adds a vcpu to a virtual machine. The vcpu id is a small integer
> -in the range [0, max_vcpus). You can use KVM_CAP_NR_VCPUS of the
> -KVM_CHECK_EXTENSION ioctl() to determine the value for max_vcpus at run-time.
> +in the range [0, max_vcpus).
> +
> +The recommended max_vcpus value can be retrieved using the KVM_CAP_NR_VCPUS of
> +the KVM_CHECK_EXTENSION ioctl() at run-time.
> +The maximum possible value for max_vcpus can be retrieved using the
> +KVM_CAP_MAX_VCPUS of the KVM_CHECK_EXTENSION ioctl() at run-time.
> +
> If the KVM_CAP_NR_VCPUS does not exist, you should assume that max_vcpus is 4
> cpus max.
> +If the KVM_CAP_MAX_VCPUS does not exist, you should assume that max_vcpus is
> +same as the value returned from KVM_CAP_NR_VCPUS.
>
> 4.8 KVM_GET_DIRTY_LOG (vm ioctl)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index d2ac8e2..7db3e66 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -26,7 +26,8 @@
> #include <asm/mtrr.h>
> #include <asm/msr-index.h>
>
> -#define KVM_MAX_VCPUS 64
> +#define KVM_MAX_VCPUS 1024
> +#define KVM_SOFT_MAX_VCPUS 64
> #define KVM_MEMORY_SLOTS 32
> /* memory slots that does not exposed to userspace */
> #define KVM_PRIVATE_MEM_SLOTS 4
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 77c9d86..9766f46 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2006,6 +2006,9 @@ int kvm_dev_ioctl_check_extension(long ext)
> r = !kvm_x86_ops->cpu_has_accelerated_tpr();
> break;
> case KVM_CAP_NR_VCPUS:
> + r = KVM_SOFT_MAX_VCPUS;
> + break;
> + case KVM_CAP_MAX_VCPUS:
> r = KVM_MAX_VCPUS;
> break;
> case KVM_CAP_NR_MEMSLOTS:
> diff --git a/include/linux/kvm.h b/include/linux/kvm.h
> index 55ef181..077c193 100644
> --- a/include/linux/kvm.h
> +++ b/include/linux/kvm.h
> @@ -457,7 +457,7 @@ struct kvm_ppc_pvinfo {
> #define KVM_CAP_VAPIC 6
> #define KVM_CAP_EXT_CPUID 7
> #define KVM_CAP_CLOCKSOURCE 8
> -#define KVM_CAP_NR_VCPUS 9 /* returns max vcpus per vm */
> +#define KVM_CAP_NR_VCPUS 9 /* returns recommended max vcpus per vm */
> #define KVM_CAP_NR_MEMSLOTS 10 /* returns max memory slots per vm */
> #define KVM_CAP_PIT 11
> #define KVM_CAP_NOP_IO_DELAY 12
> @@ -544,6 +544,7 @@ struct kvm_ppc_pvinfo {
> #define KVM_CAP_TSC_CONTROL 60
> #define KVM_CAP_GET_TSC_KHZ 61
> #define KVM_CAP_PPC_BOOKE_SREGS 62
> +#define KVM_CAP_MAX_VCPUS 63 /* returns max vcpus per vm */
>
> #ifdef KVM_CAP_IRQ_ROUTING
>
--
Sasha.
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