Commit a76733a9 authored by Xiaoyao Li's avatar Xiaoyao Li Committed by Paolo Bonzini
Browse files

KVM: x86: Introduce kvm_check_cpuid() 



Use kvm_check_cpuid() to validate if userspace provides legal cpuid
settings and call it before KVM take any action to update CPUID or
update vcpu states based on given CPUID settings.

Signed-off-by: default avatarXiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20200709043426.92712-2-xiaoyao.li@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 36f37648

arch/x86/kvm/cpuid.c

+35 −20
Original line number Diff line number Diff line
@@ -54,7 +54,26 @@ static u32 xstate_required_size(u64 xstate_bv, bool compacted) 


#define F feature_bit



int kvm_update_cpuid(struct kvm_vcpu *vcpu)

static int kvm_check_cpuid(struct kvm_vcpu *vcpu)

{

	struct kvm_cpuid_entry2 *best;



	/*

	 * The existing code assumes virtual address is 48-bit or 57-bit in the

	 * canonical address checks; exit if it is ever changed.

	 */

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

	if (best) {

		int vaddr_bits = (best->eax & 0xff00) >> 8;



		if (vaddr_bits != 48 && vaddr_bits != 57 && vaddr_bits != 0)

			return -EINVAL;

	}



	return 0;

}



void kvm_update_cpuid(struct kvm_vcpu *vcpu)

{

	struct kvm_cpuid_entry2 *best;

	struct kvm_lapic *apic = vcpu->arch.apic;
@@ -98,18 +117,6 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu) 
		     cpuid_entry_has(best, X86_FEATURE_XSAVEC)))

		best->ebx = xstate_required_size(vcpu->arch.xcr0, true);



	/*

	 * The existing code assumes virtual address is 48-bit or 57-bit in the

	 * canonical address checks; exit if it is ever changed.

	 */

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

	if (best) {

		int vaddr_bits = (best->eax & 0xff00) >> 8;



		if (vaddr_bits != 48 && vaddr_bits != 57 && vaddr_bits != 0)

			return -EINVAL;

	}



	best = kvm_find_cpuid_entry(vcpu, KVM_CPUID_FEATURES, 0);

	if (kvm_hlt_in_guest(vcpu->kvm) && best &&

		(best->eax & (1 << KVM_FEATURE_PV_UNHALT)))
@@ -131,7 +138,6 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu) 
	kvm_pmu_refresh(vcpu);

	vcpu->arch.cr4_guest_rsvd_bits =

	    __cr4_reserved_bits(guest_cpuid_has, vcpu);

	return 0;

}



static int is_efer_nx(void)
@@ -206,11 +212,16 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu, 
		vcpu->arch.cpuid_entries[i].padding[2] = 0;

	}

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

	r = kvm_check_cpuid(vcpu);

	if (r) {

		vcpu->arch.cpuid_nent = 0;

		kvfree(cpuid_entries);

		goto out;

	}



	cpuid_fix_nx_cap(vcpu);

	kvm_x86_ops.cpuid_update(vcpu);

	r = kvm_update_cpuid(vcpu);

	if (r)

		vcpu->arch.cpuid_nent = 0;

	kvm_update_cpuid(vcpu);



	kvfree(cpuid_entries);

out:
@@ -231,10 +242,14 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu, 
			   cpuid->nent * sizeof(struct kvm_cpuid_entry2)))

		goto out;

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

	kvm_x86_ops.cpuid_update(vcpu);

	r = kvm_update_cpuid(vcpu);

	if (r)

	r = kvm_check_cpuid(vcpu);

	if (r) {

		vcpu->arch.cpuid_nent = 0;

		goto out;

	}



	kvm_x86_ops.cpuid_update(vcpu);

	kvm_update_cpuid(vcpu);

out:

	return r;

}

arch/x86/kvm/cpuid.h

+1 −1
Original line number Diff line number Diff line
@@ -9,7 +9,7 @@ 
extern u32 kvm_cpu_caps[NCAPINTS] __read_mostly;

void kvm_set_cpu_caps(void);



int kvm_update_cpuid(struct kvm_vcpu *vcpu);

void 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,