Commit f69858fc authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Paolo Bonzini
Browse files

KVM: x86: disconnect kvm_check_cpuid() from vcpu->arch.cpuid_entries 



As a preparatory step to allocating vcpu->arch.cpuid_entries dynamically
make kvm_check_cpuid() check work with an arbitrary 'struct kvm_cpuid_entry2'
array.

Currently, when kvm_check_cpuid() fails we reset vcpu->arch.cpuid_nent to
0 and this is kind of weird, i.e. one would expect CPUIDs to remain
unchanged when KVM_SET_CPUID[2] call fails.

No functional change intended. It would've been possible to move the updated
kvm_check_cpuid() in kvm_vcpu_ioctl_set_cpuid2() and check the supplied
input before we start updating vcpu->arch.cpuid_entries/nent but we
can't do the same in kvm_vcpu_ioctl_set_cpuid() as we'll have to copy
'struct kvm_cpuid_entry' entries first. The change will be made when
vcpu->arch.cpuid_entries[] array becomes allocated dynamically.

Suggested-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20201001130541.1398392-2-vkuznets@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 3ee6fb49

arch/x86/kvm/cpuid.c

+23 −15
Original line number Diff line number Diff line
@@ -54,7 +54,24 @@ static u32 xstate_required_size(u64 xstate_bv, bool compacted) 


#define F feature_bit



static int kvm_check_cpuid(struct kvm_vcpu *vcpu)

static inline struct kvm_cpuid_entry2 *cpuid_entry2_find(

	struct kvm_cpuid_entry2 *entries, int nent, u32 function, u32 index)

{

	struct kvm_cpuid_entry2 *e;

	int i;



	for (i = 0; i < nent; i++) {

		e = &entries[i];



		if (e->function == function && (e->index == index ||

		    !(e->flags & KVM_CPUID_FLAG_SIGNIFCANT_INDEX)))

			return e;

	}



	return NULL;

}



static int kvm_check_cpuid(struct kvm_cpuid_entry2 *entries, int nent)

{

	struct kvm_cpuid_entry2 *best;
@@ -62,7 +79,7 @@ static int kvm_check_cpuid(struct kvm_vcpu *vcpu) 
	 * 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);

	best = cpuid_entry2_find(entries, nent, 0x80000008, 0);

	if (best) {

		int vaddr_bits = (best->eax & 0xff00) >> 8;
@@ -227,7 +244,7 @@ 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);

	r = kvm_check_cpuid(vcpu->arch.cpuid_entries, cpuid->nent);

	if (r) {

		vcpu->arch.cpuid_nent = 0;

		kvfree(cpuid_entries);
@@ -257,7 +274,7 @@ 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;

	r = kvm_check_cpuid(vcpu);

	r = kvm_check_cpuid(vcpu->arch.cpuid_entries, cpuid->nent);

	if (r) {

		vcpu->arch.cpuid_nent = 0;

		goto out;
@@ -947,17 +964,8 @@ int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid, 
struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,

					      u32 function, u32 index)

{

	struct kvm_cpuid_entry2 *e;

	int i;



	for (i = 0; i < vcpu->arch.cpuid_nent; ++i) {

		e = &vcpu->arch.cpuid_entries[i];



		if (e->function == function && (e->index == index ||

		    !(e->flags & KVM_CPUID_FLAG_SIGNIFCANT_INDEX)))

			return e;

	}

	return NULL;

	return cpuid_entry2_find(vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent,

				 function, index);

}

EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry);