Commit 25d92081 authored by Yang Zhang's avatar Yang Zhang Committed by Paolo Bonzini
Browse files

nEPT: Add nEPT violation/misconfigration support 



Inject nEPT fault to L1 guest. This patch is original from Xinhao.

Reviewed-by: default avatarXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: default avatarJun Nakajima <jun.nakajima@intel.com>
Signed-off-by: default avatarXinhao Xu <xinhao.xu@intel.com>
Signed-off-by: default avatarYang Zhang <yang.z.zhang@Intel.com>
Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 53166229

arch/x86/include/asm/kvm_host.h

+4 −0
Original line number Diff line number Diff line
@@ -286,6 +286,7 @@ struct kvm_mmu { 
	u64 *pae_root;

	u64 *lm_root;

	u64 rsvd_bits_mask[2][4];

	u64 bad_mt_xwr;



	/*

	 * Bitmap: bit set = last pte in walk
@@ -512,6 +513,9 @@ struct kvm_vcpu_arch { 
	 * instruction.

	 */

	bool write_fault_to_shadow_pgtable;



	/* set at EPT violation at this point */

	unsigned long exit_qualification;

};



struct kvm_lpage_info {

arch/x86/kvm/mmu.c

+50 −11
Original line number Diff line number Diff line
@@ -3519,6 +3519,8 @@ static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu, 
	int maxphyaddr = cpuid_maxphyaddr(vcpu);

	u64 exb_bit_rsvd = 0;



	context->bad_mt_xwr = 0;



	if (!context->nx)

		exb_bit_rsvd = rsvd_bits(63, 63);

	switch (context->root_level) {
@@ -3574,7 +3576,40 @@ static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu, 
	}

}



static void update_permission_bitmask(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu)

static void reset_rsvds_bits_mask_ept(struct kvm_vcpu *vcpu,

		struct kvm_mmu *context, bool execonly)

{

	int maxphyaddr = cpuid_maxphyaddr(vcpu);

	int pte;



	context->rsvd_bits_mask[0][3] =

		rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 7);

	context->rsvd_bits_mask[0][2] =

		rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 6);

	context->rsvd_bits_mask[0][1] =

		rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 6);

	context->rsvd_bits_mask[0][0] = rsvd_bits(maxphyaddr, 51);



	/* large page */

	context->rsvd_bits_mask[1][3] = context->rsvd_bits_mask[0][3];

	context->rsvd_bits_mask[1][2] =

		rsvd_bits(maxphyaddr, 51) | rsvd_bits(12, 29);

	context->rsvd_bits_mask[1][1] =

		rsvd_bits(maxphyaddr, 51) | rsvd_bits(12, 20);

	context->rsvd_bits_mask[1][0] = context->rsvd_bits_mask[0][0];



	for (pte = 0; pte < 64; pte++) {

		int rwx_bits = pte & 7;

		int mt = pte >> 3;

		if (mt == 0x2 || mt == 0x3 || mt == 0x7 ||

				rwx_bits == 0x2 || rwx_bits == 0x6 ||

				(rwx_bits == 0x4 && !execonly))

			context->bad_mt_xwr |= (1ull << pte);

	}

}



static void update_permission_bitmask(struct kvm_vcpu *vcpu,

		struct kvm_mmu *mmu, bool ept)

{

	unsigned bit, byte, pfec;

	u8 map;
@@ -3592,12 +3627,16 @@ static void update_permission_bitmask(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu 
			w = bit & ACC_WRITE_MASK;

			u = bit & ACC_USER_MASK;



			if (!ept) {

				/* Not really needed: !nx will cause pte.nx to fault */

				x |= !mmu->nx;

				/* Allow supervisor writes if !cr0.wp */

				w |= !is_write_protection(vcpu) && !uf;

				/* Disallow supervisor fetches of user code if cr4.smep */

				x &= !(smep && u && !uf);

			} else

				/* Not really needed: no U/S accesses on ept  */

				u = 1;



			fault = (ff && !x) || (uf && !u) || (wf && !w);

			map |= fault << bit;
@@ -3632,7 +3671,7 @@ static int paging64_init_context_common(struct kvm_vcpu *vcpu, 
	context->root_level = level;



	reset_rsvds_bits_mask(vcpu, context);

	update_permission_bitmask(vcpu, context);

	update_permission_bitmask(vcpu, context, false);

	update_last_pte_bitmap(vcpu, context);



	ASSERT(is_pae(vcpu));
@@ -3662,7 +3701,7 @@ static int paging32_init_context(struct kvm_vcpu *vcpu, 
	context->root_level = PT32_ROOT_LEVEL;



	reset_rsvds_bits_mask(vcpu, context);

	update_permission_bitmask(vcpu, context);

	update_permission_bitmask(vcpu, context, false);

	update_last_pte_bitmap(vcpu, context);



	context->new_cr3 = paging_new_cr3;
@@ -3724,7 +3763,7 @@ static int init_kvm_tdp_mmu(struct kvm_vcpu *vcpu) 
		context->gva_to_gpa = paging32_gva_to_gpa;

	}



	update_permission_bitmask(vcpu, context);

	update_permission_bitmask(vcpu, context, false);

	update_last_pte_bitmap(vcpu, context);



	return 0;
@@ -3803,7 +3842,7 @@ static int init_kvm_nested_mmu(struct kvm_vcpu *vcpu) 
		g_context->gva_to_gpa = paging32_gva_to_gpa_nested;

	}



	update_permission_bitmask(vcpu, g_context);

	update_permission_bitmask(vcpu, g_context, false);

	update_last_pte_bitmap(vcpu, g_context);



	return 0;

arch/x86/kvm/paging_tmpl.h

+22 −3
Original line number Diff line number Diff line
@@ -129,10 +129,10 @@ static inline void FNAME(protect_clean_gpte)(unsigned *access, unsigned gpte) 


static bool FNAME(is_rsvd_bits_set)(struct kvm_mmu *mmu, u64 gpte, int level)

{

	int bit7;

	int bit7 = (gpte >> 7) & 1, low6 = gpte & 0x3f;



	bit7 = (gpte >> 7) & 1;

	return (gpte & mmu->rsvd_bits_mask[bit7][level-1]) != 0;

	return (gpte & mmu->rsvd_bits_mask[bit7][level-1]) |

		((mmu->bad_mt_xwr & (1ull << low6)) != 0);

}



static inline int FNAME(is_present_gpte)(unsigned long pte)
@@ -386,6 +386,25 @@ error: 
	walker->fault.vector = PF_VECTOR;

	walker->fault.error_code_valid = true;

	walker->fault.error_code = errcode;



#if PTTYPE == PTTYPE_EPT

	/*

	 * Use PFERR_RSVD_MASK in error_code to to tell if EPT

	 * misconfiguration requires to be injected. The detection is

	 * done by is_rsvd_bits_set() above.

	 *

	 * We set up the value of exit_qualification to inject:

	 * [2:0] - Derive from [2:0] of real exit_qualification at EPT violation

	 * [5:3] - Calculated by the page walk of the guest EPT page tables

	 * [7:8] - Derived from [7:8] of real exit_qualification

	 *

	 * The other bits are set to 0.

	 */

	if (!(errcode & PFERR_RSVD_MASK)) {

		vcpu->arch.exit_qualification &= 0x187;

		vcpu->arch.exit_qualification |= ((pt_access & pte) & 0x7) << 3;

	}

#endif

	walker->fault.address = addr;

	walker->fault.nested_page_fault = mmu != vcpu->arch.walk_mmu;

arch/x86/kvm/vmx.c

+19 −0
Original line number Diff line number Diff line
@@ -5317,9 +5317,13 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu) 


	/* It is a write fault? */

	error_code = exit_qualification & (1U << 1);

	/* It is a fetch fault? */

	error_code |= (exit_qualification & (1U << 2)) << 2;

	/* ept page table is present? */

	error_code |= (exit_qualification >> 3) & 0x1;



	vcpu->arch.exit_qualification = exit_qualification;



	return kvm_mmu_page_fault(vcpu, gpa, error_code, NULL, 0);

}
@@ -7348,6 +7352,21 @@ static void vmx_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry) 
		entry->ecx |= bit(X86_FEATURE_VMX);

}



static void nested_ept_inject_page_fault(struct kvm_vcpu *vcpu,

		struct x86_exception *fault)

{

	struct vmcs12 *vmcs12;

	nested_vmx_vmexit(vcpu);

	vmcs12 = get_vmcs12(vcpu);



	if (fault->error_code & PFERR_RSVD_MASK)

		vmcs12->vm_exit_reason = EXIT_REASON_EPT_MISCONFIG;

	else

		vmcs12->vm_exit_reason = EXIT_REASON_EPT_VIOLATION;

	vmcs12->exit_qualification = vcpu->arch.exit_qualification;

	vmcs12->guest_physical_address = fault->address;

}



/*

 * prepare_vmcs02 is called when the L1 guest hypervisor runs its nested

 * L2 guest. L1 has a vmcs for L2 (vmcs12), and this function "merges" it