Commit bc1a5cd0 authored by Isaku Yamahata's avatar Isaku Yamahata Committed by Paolo Bonzini
Browse files

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: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarIsaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: default avatarRick Edgecombe <rick.p.edgecombe@intel.com>
Message-ID: <819322b8f25971f2b9933bfa4506e618508ad782.1712785629.git.isaku.yamahata@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 9aed7a6c

include/linux/kvm_host.h

+5 −0
Original line number Diff line number Diff line
@@ -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

include/uapi/linux/kvm.h

+10 −0
Original line number Diff line number Diff line
@@ -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 */

virt/kvm/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -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)

virt/kvm/kvm_main.c

+60 −0
Original line number Diff line number Diff line
@@ -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 @@ static long kvm_vcpu_ioctl(struct file *filp, 
		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);

	}