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Commit 41ab9372 authored by Bandan Das's avatar Bandan Das Committed by Paolo Bonzini
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KVM: nVMX: Emulate EPTP switching for the L1 hypervisor 



When L2 uses vmfunc, L0 utilizes the associated vmexit to
emulate a switching of the ept pointer by reloading the
guest MMU.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarBandan Das <bsd@redhat.com>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
parent 27c42a1b

arch/x86/include/asm/vmx.h

+6 −0
Original line number Diff line number Diff line
@@ -115,6 +115,10 @@ 
#define VMX_MISC_SAVE_EFER_LMA			0x00000020

#define VMX_MISC_ACTIVITY_HLT			0x00000040



/* VMFUNC functions */

#define VMX_VMFUNC_EPTP_SWITCHING               0x00000001

#define VMFUNC_EPTP_ENTRIES  512



static inline u32 vmx_basic_vmcs_revision_id(u64 vmx_basic)

{

	return vmx_basic & GENMASK_ULL(30, 0);
@@ -200,6 +204,8 @@ enum vmcs_field { 
	EOI_EXIT_BITMAP2_HIGH           = 0x00002021,

	EOI_EXIT_BITMAP3                = 0x00002022,

	EOI_EXIT_BITMAP3_HIGH           = 0x00002023,

	EPTP_LIST_ADDRESS               = 0x00002024,

	EPTP_LIST_ADDRESS_HIGH          = 0x00002025,

	VMREAD_BITMAP                   = 0x00002026,

	VMWRITE_BITMAP                  = 0x00002028,

	XSS_EXIT_BITMAP                 = 0x0000202C,

arch/x86/kvm/vmx.c

+118 −6
Original line number Diff line number Diff line
@@ -249,6 +249,7 @@ struct __packed vmcs12 { 
	u64 eoi_exit_bitmap1;

	u64 eoi_exit_bitmap2;

	u64 eoi_exit_bitmap3;

	u64 eptp_list_address;

	u64 xss_exit_bitmap;

	u64 guest_physical_address;

	u64 vmcs_link_pointer;
@@ -771,6 +772,7 @@ static const unsigned short vmcs_field_to_offset_table[] = { 
	FIELD64(EOI_EXIT_BITMAP1, eoi_exit_bitmap1),

	FIELD64(EOI_EXIT_BITMAP2, eoi_exit_bitmap2),

	FIELD64(EOI_EXIT_BITMAP3, eoi_exit_bitmap3),

	FIELD64(EPTP_LIST_ADDRESS, eptp_list_address),

	FIELD64(XSS_EXIT_BITMAP, xss_exit_bitmap),

	FIELD64(GUEST_PHYSICAL_ADDRESS, guest_physical_address),

	FIELD64(VMCS_LINK_POINTER, vmcs_link_pointer),
@@ -1388,6 +1390,13 @@ static inline bool nested_cpu_has_vmfunc(struct vmcs12 *vmcs12) 
	return nested_cpu_has2(vmcs12, SECONDARY_EXEC_ENABLE_VMFUNC);

}



static inline bool nested_cpu_has_eptp_switching(struct vmcs12 *vmcs12)

{

	return nested_cpu_has_vmfunc(vmcs12) &&

		(vmcs12->vm_function_control &

		 VMX_VMFUNC_EPTP_SWITCHING);

}



static inline bool is_nmi(u32 intr_info)

{

	return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VALID_MASK))
@@ -2839,7 +2848,12 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx) 
	if (cpu_has_vmx_vmfunc()) {

		vmx->nested.nested_vmx_secondary_ctls_high |=

			SECONDARY_EXEC_ENABLE_VMFUNC;

		vmx->nested.nested_vmx_vmfunc_controls = 0;

		/*

		 * Advertise EPTP switching unconditionally

		 * since we emulate it

		 */

		vmx->nested.nested_vmx_vmfunc_controls =

			VMX_VMFUNC_EPTP_SWITCHING;

	}



	/*
@@ -7862,6 +7876,88 @@ static int handle_preemption_timer(struct kvm_vcpu *vcpu) 
	return 1;

}



static bool valid_ept_address(struct kvm_vcpu *vcpu, u64 address)

{

	struct vcpu_vmx *vmx = to_vmx(vcpu);

	u64 mask = address & 0x7;

	int maxphyaddr = cpuid_maxphyaddr(vcpu);



	/* Check for memory type validity */

	switch (mask) {

	case 0:

		if (!(vmx->nested.nested_vmx_ept_caps & VMX_EPTP_UC_BIT))

			return false;

		break;

	case 6:

		if (!(vmx->nested.nested_vmx_ept_caps & VMX_EPTP_WB_BIT))

			return false;

		break;

	default:

		return false;

	}



	/* Bits 5:3 must be 3 */

	if (((address >> VMX_EPT_GAW_EPTP_SHIFT) & 0x7) != VMX_EPT_DEFAULT_GAW)

		return false;



	/* Reserved bits should not be set */

	if (address >> maxphyaddr || ((address >> 7) & 0x1f))

		return false;



	/* AD, if set, should be supported */

	if ((address & VMX_EPT_AD_ENABLE_BIT)) {

		if (!(vmx->nested.nested_vmx_ept_caps & VMX_EPT_AD_BIT))

			return false;

	}



	return true;

}



static int nested_vmx_eptp_switching(struct kvm_vcpu *vcpu,

				     struct vmcs12 *vmcs12)

{

	u32 index = vcpu->arch.regs[VCPU_REGS_RCX];

	u64 address;

	bool accessed_dirty;

	struct kvm_mmu *mmu = vcpu->arch.walk_mmu;



	if (!nested_cpu_has_eptp_switching(vmcs12) ||

	    !nested_cpu_has_ept(vmcs12))

		return 1;



	if (index >= VMFUNC_EPTP_ENTRIES)

		return 1;





	if (kvm_vcpu_read_guest_page(vcpu, vmcs12->eptp_list_address >> PAGE_SHIFT,

				     &address, index * 8, 8))

		return 1;



	accessed_dirty = !!(address & VMX_EPT_AD_ENABLE_BIT);



	/*

	 * If the (L2) guest does a vmfunc to the currently

	 * active ept pointer, we don't have to do anything else

	 */

	if (vmcs12->ept_pointer != address) {

		if (!valid_ept_address(vcpu, address))

			return 1;



		kvm_mmu_unload(vcpu);

		mmu->ept_ad = accessed_dirty;

		mmu->base_role.ad_disabled = !accessed_dirty;

		vmcs12->ept_pointer = address;

		/*

		 * TODO: Check what's the correct approach in case

		 * mmu reload fails. Currently, we just let the next

		 * reload potentially fail

		 */

		kvm_mmu_reload(vcpu);

	}



	return 0;

}



static int handle_vmfunc(struct kvm_vcpu *vcpu)

{

	struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -7881,7 +7977,16 @@ static int handle_vmfunc(struct kvm_vcpu *vcpu) 
	vmcs12 = get_vmcs12(vcpu);

	if ((vmcs12->vm_function_control & (1 << function)) == 0)

		goto fail;

	WARN_ONCE(1, "VMCS12 VM function control should have been zero");



	switch (function) {

	case 0:

		if (nested_vmx_eptp_switching(vcpu, vmcs12))

			goto fail;

		break;

	default:

		goto fail;

	}

	return kvm_skip_emulated_instruction(vcpu);



fail:

	nested_vmx_vmexit(vcpu, vmx->exit_reason,
@@ -10524,10 +10629,17 @@ static int check_vmentry_prereqs(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12) 
				vmx->nested.nested_vmx_entry_ctls_high))

		return VMXERR_ENTRY_INVALID_CONTROL_FIELD;



	if (nested_cpu_has_vmfunc(vmcs12) &&

	    (vmcs12->vm_function_control &

	     ~vmx->nested.nested_vmx_vmfunc_controls))

	if (nested_cpu_has_vmfunc(vmcs12)) {

		if (vmcs12->vm_function_control &

		    ~vmx->nested.nested_vmx_vmfunc_controls)

			return VMXERR_ENTRY_INVALID_CONTROL_FIELD;



		if (nested_cpu_has_eptp_switching(vmcs12)) {

			if (!nested_cpu_has_ept(vmcs12) ||

			    !page_address_valid(vcpu, vmcs12->eptp_list_address))

				return VMXERR_ENTRY_INVALID_CONTROL_FIELD;

		}

	}



	if (vmcs12->cr3_target_count > nested_cpu_vmx_misc_cr3_count(vcpu))

		return VMXERR_ENTRY_INVALID_CONTROL_FIELD;