Commit a7a2c72a authored by Oliver Upton's avatar Oliver Upton
Browse files

KVM: arm64: Separate out feature sanitisation and initialisation 

kvm_vcpu_set_target() iteratively sanitises and copies feature flags in
one go. This is rather odd, especially considering the fact that bitmap
accessors can do the heavy lifting. A subsequent change will make vCPU
features VM-wide, and fitting that into the present implementation is
just a chore.

Rework the whole thing to use bitmap accessors to sanitise and copy
flags.

Link: https://lore.kernel.org/r/20230609190054.1542113-2-oliver.upton@linux.dev


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent 44c026a7

arch/arm64/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ 
#define KVM_MAX_VCPUS VGIC_V3_MAX_CPUS



#define KVM_VCPU_MAX_FEATURES 7

#define KVM_VCPU_VALID_FEATURES	(BIT(KVM_VCPU_MAX_FEATURES) - 1)



#define KVM_REQ_SLEEP \

	KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)

arch/arm64/kvm/arm.c

+47 −28
Original line number Diff line number Diff line
@@ -1167,42 +1167,40 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level, 
	return -EINVAL;

}



static int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,

static int kvm_vcpu_init_check_features(struct kvm_vcpu *vcpu,

					const struct kvm_vcpu_init *init)

{

	unsigned int i, ret;

	u32 phys_target = kvm_target_cpu();



	if (init->target != phys_target)

		return -EINVAL;



	/*

	 * Secondary and subsequent calls to KVM_ARM_VCPU_INIT must

	 * use the same target.

	 */

	if (vcpu->arch.target != -1 && vcpu->arch.target != init->target)

		return -EINVAL;

	unsigned long features = init->features[0];

	int i;



	/* -ENOENT for unknown features, -EINVAL for invalid combinations. */

	for (i = 0; i < sizeof(init->features) * 8; i++) {

		bool set = (init->features[i / 32] & (1 << (i % 32)));

	if (features & ~KVM_VCPU_VALID_FEATURES)

		return -ENOENT;



		if (set && i >= KVM_VCPU_MAX_FEATURES)

	for (i = 1; i < ARRAY_SIZE(init->features); i++) {

		if (init->features[i])

			return -ENOENT;

	}



		/*

		 * Secondary and subsequent calls to KVM_ARM_VCPU_INIT must

		 * use the same feature set.

		 */

		if (vcpu->arch.target != -1 && i < KVM_VCPU_MAX_FEATURES &&

		    test_bit(i, vcpu->arch.features) != set)

			return -EINVAL;

	return 0;

}



		if (set)

			set_bit(i, vcpu->arch.features);

static bool kvm_vcpu_init_changed(struct kvm_vcpu *vcpu,

				  const struct kvm_vcpu_init *init)

{

	unsigned long features = init->features[0];



	return !bitmap_equal(vcpu->arch.features, &features, KVM_VCPU_MAX_FEATURES) ||

			vcpu->arch.target != init->target;

}



	vcpu->arch.target = phys_target;

static int __kvm_vcpu_set_target(struct kvm_vcpu *vcpu,

				 const struct kvm_vcpu_init *init)

{

	unsigned long features = init->features[0];

	int ret;



	vcpu->arch.target = init->target;

	bitmap_copy(vcpu->arch.features, &features, KVM_VCPU_MAX_FEATURES);



	/* Now we know what it is, we can reset it. */

	ret = kvm_reset_vcpu(vcpu);
@@ -1214,6 +1212,27 @@ static int kvm_vcpu_set_target(struct kvm_vcpu *vcpu, 
	return ret;

}



static int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,

			       const struct kvm_vcpu_init *init)

{

	int ret;



	if (init->target != kvm_target_cpu())

		return -EINVAL;



	ret = kvm_vcpu_init_check_features(vcpu, init);

	if (ret)

		return ret;



	if (vcpu->arch.target == -1)

		return __kvm_vcpu_set_target(vcpu, init);



	if (kvm_vcpu_init_changed(vcpu, init))

		return -EINVAL;



	return kvm_reset_vcpu(vcpu);

}



static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,

					 struct kvm_vcpu_init *init)

{