Commit 761e4169 authored by Krish Sadhukhan's avatar Krish Sadhukhan Committed by Paolo Bonzini
Browse files

KVM: nSVM: Check that MBZ bits in CR3 and CR4 are not set on vmrun of nested guests 



According to section "Canonicalization and Consistency Checks" in APM vol. 2
the following guest state is illegal:

    "Any MBZ bit of CR3 is set."
    "Any MBZ bit of CR4 is set."

Suggeted-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarKrish Sadhukhan <krish.sadhukhan@oracle.com>
Message-Id: <1594168797-29444-3-git-send-email-krish.sadhukhan@oracle.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 53efe527

arch/x86/kvm/svm/nested.c

+24 −2
Original line number Diff line number Diff line
@@ -222,8 +222,9 @@ static bool nested_vmcb_check_controls(struct vmcb_control_area *control) 
	return true;

}



static bool nested_vmcb_checks(struct vmcb *vmcb)

static bool nested_vmcb_checks(struct vcpu_svm *svm, struct vmcb *vmcb)

{

	bool nested_vmcb_lma;

	if ((vmcb->save.efer & EFER_SVME) == 0)

		return false;
@@ -234,6 +235,27 @@ static bool nested_vmcb_checks(struct vmcb *vmcb) 
	if (!kvm_dr6_valid(vmcb->save.dr6) || !kvm_dr7_valid(vmcb->save.dr7))

		return false;



	nested_vmcb_lma =

	        (vmcb->save.efer & EFER_LME) &&

		(vmcb->save.cr0 & X86_CR0_PG);



	if (!nested_vmcb_lma) {

		if (vmcb->save.cr4 & X86_CR4_PAE) {

			if (vmcb->save.cr3 & MSR_CR3_LEGACY_PAE_RESERVED_MASK)

				return false;

		} else {

			if (vmcb->save.cr3 & MSR_CR3_LEGACY_RESERVED_MASK)

				return false;

		}

	} else {

		if (!(vmcb->save.cr4 & X86_CR4_PAE) ||

		    !(vmcb->save.cr0 & X86_CR0_PE) ||

		    (vmcb->save.cr3 & MSR_CR3_LONG_RESERVED_MASK))

			return false;

	}

	if (kvm_valid_cr4(&svm->vcpu, vmcb->save.cr4))

		return false;



	return nested_vmcb_check_controls(&vmcb->control);

}
@@ -419,7 +441,7 @@ int nested_svm_vmrun(struct vcpu_svm *svm) 


	nested_vmcb = map.hva;



	if (!nested_vmcb_checks(nested_vmcb)) {

	if (!nested_vmcb_checks(svm, nested_vmcb)) {

		nested_vmcb->control.exit_code    = SVM_EXIT_ERR;

		nested_vmcb->control.exit_code_hi = 0;

		nested_vmcb->control.exit_info_1  = 0;

arch/x86/kvm/svm/svm.h

+4 −1
Original line number Diff line number Diff line
@@ -343,6 +343,9 @@ static inline bool gif_set(struct vcpu_svm *svm) 
}



/* svm.c */

#define MSR_CR3_LEGACY_RESERVED_MASK		0xfe7U

#define MSR_CR3_LEGACY_PAE_RESERVED_MASK	0x7U

#define MSR_CR3_LONG_RESERVED_MASK		0xfff0000000000fe7U

#define MSR_INVALID				0xffffffffU



u32 svm_msrpm_offset(u32 msr);

arch/x86/kvm/x86.c

+2 −1
Original line number Diff line number Diff line
@@ -955,7 +955,7 @@ int kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr) 
}

EXPORT_SYMBOL_GPL(kvm_set_xcr);



static int kvm_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)

int kvm_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)

{

	if (cr4 & cr4_reserved_bits)

		return -EINVAL;
@@ -965,6 +965,7 @@ static int kvm_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) 


	return 0;

}

EXPORT_SYMBOL_GPL(kvm_valid_cr4);



int kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)

{

arch/x86/kvm/x86.h

+1 −0
Original line number Diff line number Diff line
@@ -369,6 +369,7 @@ static inline bool kvm_dr6_valid(u64 data) 
void kvm_load_guest_xsave_state(struct kvm_vcpu *vcpu);

void kvm_load_host_xsave_state(struct kvm_vcpu *vcpu);

u64 kvm_spec_ctrl_valid_bits(struct kvm_vcpu *vcpu);

int kvm_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4);

bool kvm_vcpu_exit_request(struct kvm_vcpu *vcpu);



#define  KVM_MSR_RET_INVALID  2

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