From bc1a5cd002116552db4c3541e91f8a5b1b0cf65d Mon Sep 17 00:00:00 2001 From: Isaku Yamahata Date: Wed, 10 Apr 2024 15:07:28 -0700 Subject: KVM: Add KVM_PRE_FAULT_MEMORY vcpu ioctl to pre-populate guest memory Add a new ioctl KVM_PRE_FAULT_MEMORY in the KVM common code. It iterates on the memory range and calls the arch-specific function. The implementation is optional and enabled by a Kconfig symbol. Suggested-by: Sean Christopherson Signed-off-by: Isaku Yamahata Reviewed-by: Rick Edgecombe Message-ID: <819322b8f25971f2b9933bfa4506e618508ad782.1712785629.git.isaku.yamahata@intel.com> Signed-off-by: Paolo Bonzini --- include/linux/kvm_host.h | 5 ++++ include/uapi/linux/kvm.h | 10 ++++++++ virt/kvm/Kconfig | 3 +++ virt/kvm/kvm_main.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 78 insertions(+) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 7b57878c8c18..c3c922bf077f 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -2477,4 +2477,9 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t gfn, void __user *src, long npages void kvm_arch_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end); #endif +#ifdef CONFIG_KVM_GENERIC_PRE_FAULT_MEMORY +long kvm_arch_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu, + struct kvm_pre_fault_memory *range); +#endif + #endif diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index d03842abae57..e5af8c692dc0 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -917,6 +917,7 @@ struct kvm_enable_cap { #define KVM_CAP_MEMORY_ATTRIBUTES 233 #define KVM_CAP_GUEST_MEMFD 234 #define KVM_CAP_VM_TYPES 235 +#define KVM_CAP_PRE_FAULT_MEMORY 236 struct kvm_irq_routing_irqchip { __u32 irqchip; @@ -1548,4 +1549,13 @@ struct kvm_create_guest_memfd { __u64 reserved[6]; }; +#define KVM_PRE_FAULT_MEMORY _IOWR(KVMIO, 0xd5, struct kvm_pre_fault_memory) + +struct kvm_pre_fault_memory { + __u64 gpa; + __u64 size; + __u64 flags; + __u64 padding[5]; +}; + #endif /* __LINUX_KVM_H */ diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig index 754c6c923427..b14e14cdbfb9 100644 --- a/virt/kvm/Kconfig +++ b/virt/kvm/Kconfig @@ -67,6 +67,9 @@ config HAVE_KVM_INVALID_WAKEUPS config KVM_GENERIC_DIRTYLOG_READ_PROTECT bool +config KVM_GENERIC_PRE_FAULT_MEMORY + bool + config KVM_COMPAT def_bool y depends on KVM && COMPAT && !(S390 || ARM64 || RISCV) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 8e422c2c9450..f817ec66c85f 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4373,6 +4373,52 @@ static int kvm_vcpu_ioctl_get_stats_fd(struct kvm_vcpu *vcpu) return fd; } +#ifdef CONFIG_KVM_GENERIC_PRE_FAULT_MEMORY +static int kvm_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu, + struct kvm_pre_fault_memory *range) +{ + int idx; + long r; + u64 full_size; + + if (range->flags) + return -EINVAL; + + if (!PAGE_ALIGNED(range->gpa) || + !PAGE_ALIGNED(range->size) || + range->gpa + range->size <= range->gpa) + return -EINVAL; + + vcpu_load(vcpu); + idx = srcu_read_lock(&vcpu->kvm->srcu); + + full_size = range->size; + do { + if (signal_pending(current)) { + r = -EINTR; + break; + } + + r = kvm_arch_vcpu_pre_fault_memory(vcpu, range); + if (WARN_ON_ONCE(r == 0 || r == -EIO)) + break; + + if (r < 0) + break; + + range->size -= r; + range->gpa += r; + cond_resched(); + } while (range->size); + + srcu_read_unlock(&vcpu->kvm->srcu, idx); + vcpu_put(vcpu); + + /* Return success if at least one page was mapped successfully. */ + return full_size == range->size ? r : 0; +} +#endif + static long kvm_vcpu_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) { @@ -4573,6 +4619,20 @@ out_free1: r = kvm_vcpu_ioctl_get_stats_fd(vcpu); break; } +#ifdef CONFIG_KVM_GENERIC_PRE_FAULT_MEMORY + case KVM_PRE_FAULT_MEMORY: { + struct kvm_pre_fault_memory range; + + r = -EFAULT; + if (copy_from_user(&range, argp, sizeof(range))) + break; + r = kvm_vcpu_pre_fault_memory(vcpu, &range); + /* Pass back leftover range. */ + if (copy_to_user(argp, &range, sizeof(range))) + r = -EFAULT; + break; + } +#endif default: r = kvm_arch_vcpu_ioctl(filp, ioctl, arg); } -- cgit v1.2.3