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Commit dd598091 authored by Nadav Amit's avatar Nadav Amit Committed by Paolo Bonzini
Browse files

KVM: x86: Warn if guest virtual address space is not 48-bits 



The KVM emulator code assumes that the guest virtual address space (in 64-bit)
is 48-bits wide.  Fail the KVM_SET_CPUID and KVM_SET_CPUID2 ioctl if
userspace tries to create a guest that does not obey this restriction.

Signed-off-by: default avatarNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 3c3c29fd

arch/x86/kvm/cpuid.c

+14 −7
Original line number Diff line number Diff line
@@ -53,14 +53,14 @@ u64 kvm_supported_xcr0(void) 
	return xcr0;

}



void kvm_update_cpuid(struct kvm_vcpu *vcpu)

int kvm_update_cpuid(struct kvm_vcpu *vcpu)

{

	struct kvm_cpuid_entry2 *best;

	struct kvm_lapic *apic = vcpu->arch.apic;



	best = kvm_find_cpuid_entry(vcpu, 1, 0);

	if (!best)

		return;

		return 0;



	/* Update OSXSAVE bit */

	if (cpu_has_xsave && best->function == 0x1) {
@@ -88,7 +88,17 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu) 
			xstate_required_size(vcpu->arch.xcr0);

	}



	/*

	 * The existing code assumes virtual address is 48-bit in the canonical

	 * address checks; exit if it is ever changed.

	 */

	best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0);

	if (best && ((best->eax & 0xff00) >> 8) != 48 &&

		((best->eax & 0xff00) >> 8) != 0)

		return -EINVAL;



	kvm_pmu_cpuid_update(vcpu);

	return 0;

}



static int is_efer_nx(void)
@@ -151,10 +161,9 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu, 
	}

	vcpu->arch.cpuid_nent = cpuid->nent;

	cpuid_fix_nx_cap(vcpu);

	r = 0;

	kvm_apic_set_version(vcpu);

	kvm_x86_ops->cpuid_update(vcpu);

	kvm_update_cpuid(vcpu);

	r = kvm_update_cpuid(vcpu);



out_free:

	vfree(cpuid_entries);
@@ -178,9 +187,7 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu, 
	vcpu->arch.cpuid_nent = cpuid->nent;

	kvm_apic_set_version(vcpu);

	kvm_x86_ops->cpuid_update(vcpu);

	kvm_update_cpuid(vcpu);

	return 0;



	r = kvm_update_cpuid(vcpu);

out:

	return r;

}

arch/x86/kvm/cpuid.h

+1 −1
Original line number Diff line number Diff line
@@ -3,7 +3,7 @@ 


#include "x86.h"



void kvm_update_cpuid(struct kvm_vcpu *vcpu);

int kvm_update_cpuid(struct kvm_vcpu *vcpu);

struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,

					      u32 function, u32 index);

int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,