On 28/01/17 14:55, Andrew Jones wrote:
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?
On arm64, there is a per-cpu cpuinfo structure kept for each online CPU, which keeps cached values of the ID registers. May be we could use that here. See arch/arm64/kernel/cpuinfo.c::__cpuinfo_store_cpu() Suzuki _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
