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.

Isaku Yamahata committed 2 years ago

Commit bc1a5cd1 parent 9aed7a64 files · +78 −0Browse files

Unified · Split

4 files

include/linux/kvm_host.h +5 −0
include/uapi/linux/kvm.h +10 −0
virt/kvm/Kconfig +3 −0
virt/kvm/kvm_main.c +60 −0

include/linux/kvm_host.h+5−0

@@ -2477,4 +2477,9 @@ long kvm_gmem_populate(struct kvm kvm, gfn_t gfn, void __user src, long npages · 2476 unmodified lines
2477	2477	void kvm_arch_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end);
2478	2478	#endif
2479	2479
	2480	+#ifdef CONFIG_KVM_GENERIC_PRE_FAULT_MEMORY
	2481	+long kvm_arch_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu,
	2482	+ struct kvm_pre_fault_memory *range);
	2483	+#endif
	2484	+
2480	2485	#endif

include/uapi/linux/kvm.h+10−0

@@ -917,6 +917,7 @@ struct kvm_enable_cap { · 916 unmodified lines
917	917	#define KVM_CAP_MEMORY_ATTRIBUTES 233
918	918	#define KVM_CAP_GUEST_MEMFD 234
919	919	#define KVM_CAP_VM_TYPES 235
	920	+#define KVM_CAP_PRE_FAULT_MEMORY 236
920	921
921	922	struct kvm_irq_routing_irqchip {
922	923	__u32 irqchip;
@@ -1548,4 +1549,13 @@ struct kvm_create_guest_memfd { · 625 unmodified lines
1548	1549	__u64 reserved[6];
1549	1550	};
1550	1551
	1552	+#define KVM_PRE_FAULT_MEMORY _IOWR(KVMIO, 0xd5, struct kvm_pre_fault_memory)
	1553	+
	1554	+struct kvm_pre_fault_memory {
	1555	+ __u64 gpa;
	1556	+ __u64 size;
	1557	+ __u64 flags;
	1558	+ __u64 padding[5];
	1559	+};
	1560	+
1551	1561	#endif /* __LINUX_KVM_H */

virt/kvm/Kconfig+3−0

@@ -67,6 +67,9 @@ config HAVE_KVM_INVALID_WAKEUPS · 66 unmodified lines
67	67	config KVM_GENERIC_DIRTYLOG_READ_PROTECT
68	68	bool
69	69
	70	+config KVM_GENERIC_PRE_FAULT_MEMORY
	71	+ bool
	72	+
70	73	config KVM_COMPAT
71	74	def_bool y
72	75	depends on KVM && COMPAT && !(S390 \|\| ARM64 \|\| RISCV)

virt/kvm/kvm_main.c+60−0

@@ -4373,6 +4373,52 @@ static int kvm_vcpu_ioctl_get_stats_fd(struct kvm_vcpu *vcpu) · 4372 unmodified lines
4373	4373	return fd;
4374	4374	}
4375	4375
	4376	+#ifdef CONFIG_KVM_GENERIC_PRE_FAULT_MEMORY
	4377	+static int kvm_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu,
	4378	+ struct kvm_pre_fault_memory *range)
	4379	+{
	4380	+ int idx;
	4381	+ long r;
	4382	+ u64 full_size;
	4383	+
	4384	+ if (range->flags)
	4385	+ return -EINVAL;
	4386	+
	4387	+ if (!PAGE_ALIGNED(range->gpa) \|\|
	4388	+ !PAGE_ALIGNED(range->size) \|\|
	4389	+ range->gpa + range->size <= range->gpa)
	4390	+ return -EINVAL;
	4391	+
	4392	+ vcpu_load(vcpu);
	4393	+ idx = srcu_read_lock(&vcpu->kvm->srcu);
	4394	+
	4395	+ full_size = range->size;
	4396	+ do {
	4397	+ if (signal_pending(current)) {
	4398	+ r = -EINTR;
	4399	+ break;
	4400	+ }
	4401	+
	4402	+ r = kvm_arch_vcpu_pre_fault_memory(vcpu, range);
	4403	+ if (WARN_ON_ONCE(r == 0 \|\| r == -EIO))
	4404	+ break;
	4405	+
	4406	+ if (r < 0)
	4407	+ break;
	4408	+
	4409	+ range->size -= r;
	4410	+ range->gpa += r;
	4411	+ cond_resched();
	4412	+ } while (range->size);
	4413	+
	4414	+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
	4415	+ vcpu_put(vcpu);
	4416	+
	4417	+ /* Return success if at least one page was mapped successfully. */
	4418	+ return full_size == range->size ? r : 0;
	4419	+}
	4420	+#endif
	4421	+
4376	4422	static long kvm_vcpu_ioctl(struct file *filp,
4377	4423	unsigned int ioctl, unsigned long arg)
4378	4424	{
@@ -4573,6 +4619,20 @@ out_free1: · 194 unmodified lines
4573	4619	r = kvm_vcpu_ioctl_get_stats_fd(vcpu);
4574	4620	break;
4575	4621	}
	4622	+#ifdef CONFIG_KVM_GENERIC_PRE_FAULT_MEMORY
	4623	+ case KVM_PRE_FAULT_MEMORY: {
	4624	+ struct kvm_pre_fault_memory range;
	4625	+
	4626	+ r = -EFAULT;
	4627	+ if (copy_from_user(&range, argp, sizeof(range)))
	4628	+ break;
	4629	+ r = kvm_vcpu_pre_fault_memory(vcpu, &range);
	4630	+ /* Pass back leftover range. */
	4631	+ if (copy_to_user(argp, &range, sizeof(range)))
	4632	+ r = -EFAULT;
	4633	+ break;
	4634	+ }
	4635	+#endif
4576	4636	default:
4577	4637	r = kvm_arch_vcpu_ioctl(filp, ioctl, arg);
4578	4638	}

KVM: Add KVM_PRE_FAULT_MEMORY vcpu ioctl to pre-populate guest memory

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