On Mon, Jan 16, 2017 at 05:33:33PM +0800, Shannon Zhao wrote:
> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
>
> When initializing KVM, check whether physical hardware is a
> heterogeneous system through the MIDR values. If so, force userspace to
> set the KVM_ARM_VCPU_CROSS feature bit. Otherwise, it should fail to
> initialize VCPUs.
>
> Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> ---
> arch/arm/kvm/arm.c | 26 ++++++++++++++++++++++++++
> include/uapi/linux/kvm.h | 1 +
> 2 files changed, 27 insertions(+)
>
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index bdceb19..21ec070 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -46,6 +46,7 @@
> #include <asm/kvm_coproc.h>
> #include <asm/kvm_psci.h>
> #include <asm/sections.h>
> +#include <asm/cputype.h>
>
> #ifdef REQUIRES_VIRT
> __asm__(".arch_extension virt");
> @@ -65,6 +66,7 @@ static unsigned int kvm_vmid_bits __read_mostly;
> static DEFINE_SPINLOCK(kvm_vmid_lock);
>
> static bool vgic_present;
> +static bool heterogeneous_system;
>
> static DEFINE_PER_CPU(unsigned char, kvm_arm_hardware_enabled);
>
> @@ -210,6 +212,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> case KVM_CAP_ARM_CROSS_VCPU:
> r = 1;
> break;
> + case KVM_CAP_ARM_HETEROGENEOUS:
> + r = heterogeneous_system;
> + break;
What's this for? When/why would usespace check it?
> case KVM_CAP_COALESCED_MMIO:
> r = KVM_COALESCED_MMIO_PAGE_OFFSET;
> break;
> @@ -812,6 +817,12 @@ static int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
> int phys_target = kvm_target_cpu();
> bool cross_vcpu = kvm_vcpu_has_feature_cross_cpu(init);
>
> + if (heterogeneous_system && !cross_vcpu) {
> + kvm_err("%s:Host is a heterogeneous system, set KVM_ARM_VCPU_CROSS bit\n",
> + __func__);
> + return -EINVAL;
> + }
Instead of forcing userspace to set a bit, why not just confirm the
target selected will work? E.g. if only generic works on a heterogeneous
system then just
if (heterogeneous_system && init->target != GENERIC)
return -EINVAL
should work
> +
> if (!cross_vcpu && init->target != phys_target)
> return -EINVAL;
>
> @@ -1397,6 +1408,11 @@ static void check_kvm_target_cpu(void *ret)
> *(int *)ret = kvm_target_cpu();
> }
>
> +static void get_physical_cpu_midr(void *midr)
> +{
> + *(u32 *)midr = read_cpuid_id();
> +}
> +
> struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr)
> {
> struct kvm_vcpu *vcpu;
> @@ -1417,6 +1433,7 @@ int kvm_arch_init(void *opaque)
> {
> int err;
> int ret, cpu;
> + u32 current_midr, midr;
>
> if (!is_hyp_mode_available()) {
> kvm_err("HYP mode not available\n");
> @@ -1431,6 +1448,15 @@ int kvm_arch_init(void *opaque)
> }
> }
>
> + current_midr = read_cpuid_id();
> + for_each_online_cpu(cpu) {
> + smp_call_function_single(cpu, get_physical_cpu_midr, &midr, 1);
> + if (current_midr != midr) {
> + heterogeneous_system = true;
> + break;
> + }
> + }
Is there no core kernel API that provides this?
> +
> err = init_common_resources();
> if (err)
> return err;
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 46115a2..cc2b63d 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -872,6 +872,7 @@ struct kvm_ppc_smmu_info {
> #define KVM_CAP_MSI_DEVID 131
> #define KVM_CAP_PPC_HTM 132
> #define KVM_CAP_ARM_CROSS_VCPU 133
> +#define KVM_CAP_ARM_HETEROGENEOUS 134
>
> #ifdef KVM_CAP_IRQ_ROUTING
>
> --
> 2.0.4
>
>
drew
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