Commit b222b0b8 authored by Maxim Levitsky's avatar Maxim Levitsky Committed by Paolo Bonzini
Browse files

KVM: nSVM: refactor the CR3 reload on migration 



Document the actual reason why we need to do it
on migration and move the call to svm_set_nested_state
to be closer to VMX code.

To avoid loading the PDPTRs from possibly not up to date memory map,
in nested_svm_load_cr3 after the move, move this code to
.get_nested_state_pages.

Signed-off-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210607090203.133058-5-mlevitsk@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent c7313155

arch/x86/kvm/svm/nested.c

+25 −7
Original line number Diff line number Diff line
@@ -385,12 +385,12 @@ static inline bool nested_npt_enabled(struct vcpu_svm *svm) 
 * if we are emulating VM-Entry into a guest with NPT enabled.

 */

static int nested_svm_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3,

			       bool nested_npt)

			       bool nested_npt, bool reload_pdptrs)

{

	if (CC(kvm_vcpu_is_illegal_gpa(vcpu, cr3)))

		return -EINVAL;



	if (!nested_npt && is_pae_paging(vcpu) &&

	if (reload_pdptrs && !nested_npt && is_pae_paging(vcpu) &&

	    CC(!load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3)))

		return -EINVAL;
@@ -574,7 +574,7 @@ int enter_svm_guest_mode(struct kvm_vcpu *vcpu, u64 vmcb12_gpa, 
	nested_vmcb02_prepare_save(svm, vmcb12);



	ret = nested_svm_load_cr3(&svm->vcpu, vmcb12->save.cr3,

				  nested_npt_enabled(svm));

				  nested_npt_enabled(svm), true);

	if (ret)

		return ret;
@@ -801,7 +801,7 @@ int nested_svm_vmexit(struct vcpu_svm *svm) 


	nested_svm_uninit_mmu_context(vcpu);



	rc = nested_svm_load_cr3(vcpu, svm->vmcb->save.cr3, false);

	rc = nested_svm_load_cr3(vcpu, svm->vmcb->save.cr3, false, true);

	if (rc)

		return 1;
@@ -1297,6 +1297,19 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu, 
	    !nested_vmcb_valid_sregs(vcpu, save))

		goto out_free;



	/*

	 * While the nested guest CR3 is already checked and set by

	 * KVM_SET_SREGS, it was set when nested state was yet loaded,

	 * thus MMU might not be initialized correctly.

	 * Set it again to fix this.

	 */



	ret = nested_svm_load_cr3(&svm->vcpu, vcpu->arch.cr3,

				  nested_npt_enabled(svm), false);

	if (WARN_ON_ONCE(ret))

		goto out_free;





	/*

	 * All checks done, we can enter guest mode. Userspace provides

	 * vmcb12.control, which will be combined with L1 and stored into
@@ -1354,8 +1367,13 @@ static bool svm_get_nested_state_pages(struct kvm_vcpu *vcpu) 
	if (WARN_ON(!is_guest_mode(vcpu)))

		return true;



	if (nested_svm_load_cr3(&svm->vcpu, vcpu->arch.cr3,

				nested_npt_enabled(svm)))

	if (!nested_npt_enabled(svm) && is_pae_paging(vcpu))

		/*

		 * Reload the guest's PDPTRs since after a migration

		 * the guest CR3 might be restored prior to setting the nested

		 * state which can lead to a load of wrong PDPTRs.

		 */

		if (CC(!load_pdptrs(vcpu, vcpu->arch.walk_mmu, vcpu->arch.cr3)))

			return false;



	if (!nested_svm_vmrun_msrpm(svm)) {