Now that we have Eager Page Split support added for ARM in the kernel[0], enable it in Qemu. This adds, -eager-split-size to Qemu options to set the eager page split chunk size. -enable KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE.
The chunk size specifies how many pages to break at a time, using a single allocation. Bigger the chunk size, more pages need to be allocated ahead of time. Notes: - I am not sure whether we need to call kvm_vm_check_extension() for KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE or not as kernel seems to disable eager page size by default and it will return zero always. -ToDo: Update qemu-options.hx [0]: https://lore.kernel.org/all/168426111477.3193133.10748106199843780930.b4...@linux.dev/ Signed-off-by: Shameer Kolothum <shameerali.kolothum.th...@huawei.com> --- include/sysemu/kvm_int.h | 1 + target/arm/kvm.c | 73 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 74 insertions(+) diff --git a/include/sysemu/kvm_int.h b/include/sysemu/kvm_int.h index 511b42bde5..03a1660d40 100644 --- a/include/sysemu/kvm_int.h +++ b/include/sysemu/kvm_int.h @@ -116,6 +116,7 @@ struct KVMState uint64_t kvm_dirty_ring_bytes; /* Size of the per-vcpu dirty ring */ uint32_t kvm_dirty_ring_size; /* Number of dirty GFNs per ring */ bool kvm_dirty_ring_with_bitmap; + uint64_t kvm_eager_split_size; /* Eager Page Splitting chunk size */ struct KVMDirtyRingReaper reaper; NotifyVmexitOption notify_vmexit; uint32_t notify_window; diff --git a/target/arm/kvm.c b/target/arm/kvm.c index b4c7654f49..985d901062 100644 --- a/target/arm/kvm.c +++ b/target/arm/kvm.c @@ -30,6 +30,7 @@ #include "exec/address-spaces.h" #include "hw/boards.h" #include "hw/irq.h" +#include "qapi/visitor.h" #include "qemu/log.h" const KVMCapabilityInfo kvm_arch_required_capabilities[] = { @@ -247,6 +248,23 @@ int kvm_arm_get_max_vm_ipa_size(MachineState *ms, bool *fixed_ipa) return ret > 0 ? ret : 40; } +static bool kvm_arm_eager_split_size_valid(uint64_t req_size, uint32_t sizes) +{ + int i; + + for (i = 0; i < sizeof(uint32_t) * BITS_PER_BYTE; i++) { + if (!(sizes & (1 << i))) { + continue; + } + + if (req_size == (1 << i)) { + return true; + } + } + + return false; +} + int kvm_arch_init(MachineState *ms, KVMState *s) { int ret = 0; @@ -280,6 +298,21 @@ int kvm_arch_init(MachineState *ms, KVMState *s) } } + if (s->kvm_eager_split_size) { + uint32_t sizes; + + sizes = kvm_vm_check_extension(s, KVM_CAP_ARM_SUPPORTED_BLOCK_SIZES); + if (!sizes) { + error_report("Eager Page Split not supported on host"); + } else if (!kvm_arm_eager_split_size_valid(s->kvm_eager_split_size, + sizes)) { + error_report("Eager Page Split requested chunk size not valid"); + } else if (kvm_vm_enable_cap(s, KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE, 0, + s->kvm_eager_split_size)) { + error_report("Failed to set Eager Page Split chunk size"); + } + } + kvm_arm_init_debug(s); return ret; @@ -1062,6 +1095,46 @@ bool kvm_arch_cpu_check_are_resettable(void) return true; } +static void kvm_arch_get_eager_split_size(Object *obj, Visitor *v, + const char *name, void *opaque, + Error **errp) +{ + KVMState *s = KVM_STATE(obj); + uint64_t value = s->kvm_eager_split_size; + + visit_type_size(v, name, &value, errp); +} + +static void kvm_arch_set_eager_split_size(Object *obj, Visitor *v, + const char *name, void *opaque, + Error **errp) +{ + KVMState *s = KVM_STATE(obj); + uint64_t value; + + if (s->fd != -1) { + error_setg(errp, "Cannot set properties after the accelerator has been initialized"); + return; + } + + if (!visit_type_size(v, name, &value, errp)) { + return; + } + + if (value & (value - 1)) { + error_setg(errp, "early-split-size must be a power of two."); + return; + } + + s->kvm_eager_split_size = value; +} + void kvm_arch_accel_class_init(ObjectClass *oc) { + object_class_property_add(oc, "eager-split-size", "size", + kvm_arch_get_eager_split_size, + kvm_arch_set_eager_split_size, NULL, NULL); + + object_class_property_set_description(oc, "eager-split-size", + "Configure Eager Page Split chunk size for hugepages. (default: 0, disabled)"); } -- 2.34.1
