Commit 6e01b760 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: x86: Implement kvm_arch_vcpu_pre_fault_memory() 



Wire KVM_PRE_FAULT_MEMORY ioctl to kvm_mmu_do_page_fault() to populate guest
memory.  It can be called right after KVM_CREATE_VCPU creates a vCPU,
since at that point kvm_mmu_create() and kvm_init_mmu() are called and
the vCPU is ready to invoke the KVM page fault handler.

The helper function kvm_tdp_map_page() takes care of the logic to
process RET_PF_* return values and convert them to success or errno.

Signed-off-by: default avatarIsaku Yamahata <isaku.yamahata@intel.com>
Message-ID: <9b866a0ae7147f96571c439e75429a03dcb659b6.1712785629.git.isaku.yamahata@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 58ef2469

arch/x86/kvm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ config KVM 
	select KVM_VFIO

	select HAVE_KVM_PM_NOTIFIER if PM

	select KVM_GENERIC_HARDWARE_ENABLING

	select KVM_GENERIC_PRE_FAULT_MEMORY

	select KVM_WERROR if WERROR

	help

	  Support hosting fully virtualized guest machines using hardware

arch/x86/kvm/mmu/mmu.c

+73 −0
Original line number Diff line number Diff line
@@ -4709,6 +4709,79 @@ int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) 
	return direct_page_fault(vcpu, fault);

}



static int kvm_tdp_map_page(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code,

			    u8 *level)

{

	int r;



	/*

	 * Restrict to TDP page fault, since that's the only case where the MMU

	 * is indexed by GPA.

	 */

	if (vcpu->arch.mmu->page_fault != kvm_tdp_page_fault)

		return -EOPNOTSUPP;



	do {

		if (signal_pending(current))

			return -EINTR;

		cond_resched();

		r = kvm_mmu_do_page_fault(vcpu, gpa, error_code, true, NULL, level);

	} while (r == RET_PF_RETRY);



	if (r < 0)

		return r;



	switch (r) {

	case RET_PF_FIXED:

	case RET_PF_SPURIOUS:

		return 0;



	case RET_PF_EMULATE:

		return -ENOENT;



	case RET_PF_RETRY:

	case RET_PF_CONTINUE:

	case RET_PF_INVALID:

	default:

		WARN_ONCE(1, "could not fix page fault during prefault");

		return -EIO;

	}

}



long kvm_arch_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu,

				    struct kvm_pre_fault_memory *range)

{

	u64 error_code = PFERR_GUEST_FINAL_MASK;

	u8 level = PG_LEVEL_4K;

	u64 end;

	int r;



	/*

	 * reload is efficient when called repeatedly, so we can do it on

	 * every iteration.

	 */

	kvm_mmu_reload(vcpu);



	if (kvm_arch_has_private_mem(vcpu->kvm) &&

	    kvm_mem_is_private(vcpu->kvm, gpa_to_gfn(range->gpa)))

		error_code |= PFERR_PRIVATE_ACCESS;



	/*

	 * Shadow paging uses GVA for kvm page fault, so restrict to

	 * two-dimensional paging.

	 */

	r = kvm_tdp_map_page(vcpu, range->gpa, error_code, &level);

	if (r < 0)

		return r;



	/*

	 * If the mapping that covers range->gpa can use a huge page, it

	 * may start below it or end after range->gpa + range->size.

	 */

	end = (range->gpa & KVM_HPAGE_MASK(level)) + KVM_HPAGE_SIZE(level);

	return min(range->size, end - range->gpa);

}



static void nonpaging_init_context(struct kvm_mmu *context)

{

	context->page_fault = nonpaging_page_fault;

arch/x86/kvm/x86.c

+3 −0
Original line number Diff line number Diff line
@@ -4705,6 +4705,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) 
	case KVM_CAP_MEMORY_FAULT_INFO:

		r = 1;

		break;

	case KVM_CAP_PRE_FAULT_MEMORY:

		r = tdp_enabled;

		break;

	case KVM_CAP_EXIT_HYPERCALL:

		r = KVM_EXIT_HYPERCALL_VALID_MASK;

		break;