Commit 3f4a812e authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Paolo Bonzini
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KVM: nSVM: hyper-v: Enable L2 TLB flush 



Implement Hyper-V L2 TLB flush for nSVM. The feature needs to be enabled
both in extended 'nested controls' in VMCB and VP assist page.
According to Hyper-V TLFS, synthetic vmexit to L1 is performed with
- HV_SVM_EXITCODE_ENL exit_code.
- HV_SVM_ENL_EXITCODE_TRAP_AFTER_FLUSH exit_info_1.

Note: VP assist page is cached in 'struct kvm_vcpu_hv' so
recalc_intercepts() doesn't need to read from guest's memory. KVM
needs to update the case upon each VMRUN and after svm_set_nested_state
(svm_get_nested_state_pages()) to handle the case when the guest got
migrated while L2 was running.

Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221101145426.251680-29-vkuznets@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent b415d8d4

arch/x86/include/asm/hyperv-tlfs.h

+4 −0
Original line number Diff line number Diff line
@@ -631,6 +631,10 @@ struct hv_vmcb_enlightenments { 
 */

#define HV_VMCB_NESTED_ENLIGHTENMENTS		31



/* Synthetic VM-Exit */

#define HV_SVM_EXITCODE_ENL			0xf0000000

#define HV_SVM_ENL_EXITCODE_TRAP_AFTER_FLUSH	(1)



struct hv_partition_assist_pg {

	u32 tlb_lock_count;

};

arch/x86/kvm/hyperv.h

+11 −0
Original line number Diff line number Diff line
@@ -198,6 +198,17 @@ static inline bool kvm_hv_is_tlb_flush_hcall(struct kvm_vcpu *vcpu) 
		code == HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX);

}



static inline int kvm_hv_verify_vp_assist(struct kvm_vcpu *vcpu)

{

	if (!to_hv_vcpu(vcpu))

		return 0;



	if (!kvm_hv_assist_page_enabled(vcpu))

		return 0;



	return kvm_hv_get_assist_page(vcpu);

}



int kvm_hv_vcpu_flush_tlb(struct kvm_vcpu *vcpu);



#endif

arch/x86/kvm/svm/hyperv.c

+7 −0
Original line number Diff line number Diff line
@@ -8,4 +8,11 @@ 


void svm_hv_inject_synthetic_vmexit_post_tlb_flush(struct kvm_vcpu *vcpu)

{

	struct vcpu_svm *svm = to_svm(vcpu);



	svm->vmcb->control.exit_code = HV_SVM_EXITCODE_ENL;

	svm->vmcb->control.exit_code_hi = 0;

	svm->vmcb->control.exit_info_1 = HV_SVM_ENL_EXITCODE_TRAP_AFTER_FLUSH;

	svm->vmcb->control.exit_info_2 = 0;

	nested_svm_vmexit(svm);

}

arch/x86/kvm/svm/hyperv.h

+15 −0
Original line number Diff line number Diff line
@@ -25,6 +25,21 @@ static inline void nested_svm_hv_update_vm_vp_ids(struct kvm_vcpu *vcpu) 
	hv_vcpu->nested.vp_id = hve->hv_vp_id;

}



static inline bool nested_svm_l2_tlb_flush_enabled(struct kvm_vcpu *vcpu)

{

	struct vcpu_svm *svm = to_svm(vcpu);

	struct hv_vmcb_enlightenments *hve = &svm->nested.ctl.hv_enlightenments;

	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);



	if (!hv_vcpu)

		return false;



	if (!hve->hv_enlightenments_control.nested_flush_hypercall)

		return false;



	return hv_vcpu->vp_assist_page.nested_control.features.directhypercall;

}



void svm_hv_inject_synthetic_vmexit_post_tlb_flush(struct kvm_vcpu *vcpu);



#endif /* __ARCH_X86_KVM_SVM_HYPERV_H__ */

arch/x86/kvm/svm/nested.c

+33 −2
Original line number Diff line number Diff line
@@ -150,7 +150,11 @@ void recalc_intercepts(struct vcpu_svm *svm) 
		vmcb_clr_intercept(c, INTERCEPT_VINTR);

	}



	/* We don't want to see VMMCALLs from a nested guest */

	/*

	 * We want to see VMMCALLs from a nested guest only when Hyper-V L2 TLB

	 * flush feature is enabled.

	 */

	if (!nested_svm_l2_tlb_flush_enabled(&svm->vcpu))

		vmcb_clr_intercept(c, INTERCEPT_VMMCALL);



	for (i = 0; i < MAX_INTERCEPT; i++)
@@ -473,6 +477,15 @@ static void nested_save_pending_event_to_vmcb12(struct vcpu_svm *svm, 


static void nested_svm_transition_tlb_flush(struct kvm_vcpu *vcpu)

{

	/*

	 * KVM_REQ_HV_TLB_FLUSH flushes entries from either L1's VP_ID or

	 * L2's VP_ID upon request from the guest. Make sure we check for

	 * pending entries in the right FIFO upon L1/L2 transition as these

	 * requests are put by other vCPUs asynchronously.

	 */

	if (to_hv_vcpu(vcpu) && npt_enabled)

		kvm_make_request(KVM_REQ_HV_TLB_FLUSH, vcpu);



	/*

	 * TODO: optimize unconditional TLB flush/MMU sync.  A partial list of

	 * things to fix before this can be conditional:
@@ -824,6 +837,13 @@ int nested_svm_vmrun(struct kvm_vcpu *vcpu) 
		return 1;

	}



	/* This fails when VP assist page is enabled but the supplied GPA is bogus */

	ret = kvm_hv_verify_vp_assist(vcpu);

	if (ret) {

		kvm_inject_gp(vcpu, 0);

		return ret;

	}



	vmcb12_gpa = svm->vmcb->save.rax;

	ret = kvm_vcpu_map(vcpu, gpa_to_gfn(vmcb12_gpa), &map);

	if (ret == -EINVAL) {
@@ -1421,6 +1441,7 @@ static int svm_check_nested_events(struct kvm_vcpu *vcpu) 
int nested_svm_exit_special(struct vcpu_svm *svm)

{

	u32 exit_code = svm->vmcb->control.exit_code;

	struct kvm_vcpu *vcpu = &svm->vcpu;



	switch (exit_code) {

	case SVM_EXIT_INTR:
@@ -1439,6 +1460,13 @@ int nested_svm_exit_special(struct vcpu_svm *svm) 
			return NESTED_EXIT_HOST;

		break;

	}

	case SVM_EXIT_VMMCALL:

		/* Hyper-V L2 TLB flush hypercall is handled by L0 */

		if (guest_hv_cpuid_has_l2_tlb_flush(vcpu) &&

		    nested_svm_l2_tlb_flush_enabled(vcpu) &&

		    kvm_hv_is_tlb_flush_hcall(vcpu))

			return NESTED_EXIT_HOST;

		break;

	default:

		break;

	}
@@ -1719,6 +1747,9 @@ static bool svm_get_nested_state_pages(struct kvm_vcpu *vcpu) 
		return false;

	}



	if (kvm_hv_verify_vp_assist(vcpu))

		return false;



	return true;

}