arch/arm64/kvm/guest.c

Source file repositories/reference/linux-study-clean/arch/arm64/kvm/guest.c

File Facts

System
Linux kernel
Corpus path
arch/arm64/kvm/guest.c
Extension
.c
Size
27084 bytes
Lines
1082
Domain
Architecture Layer
Bucket
arch/arm64
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

struct sve_state_reg_region {
	unsigned int koffset;	/* offset into sve_state in kernel memory */
	unsigned int klen;	/* length in kernel memory */
	unsigned int upad;	/* extra trailing padding in user memory */
};

/*
 * Validate SVE register ID and get sanitised bounds for user/kernel SVE
 * register copy
 */
static int sve_reg_to_region(struct sve_state_reg_region *region,
			     struct kvm_vcpu *vcpu,
			     const struct kvm_one_reg *reg)
{
	/* reg ID ranges for Z- registers */
	const u64 zreg_id_min = KVM_REG_ARM64_SVE_ZREG(0, 0);
	const u64 zreg_id_max = KVM_REG_ARM64_SVE_ZREG(SVE_NUM_ZREGS - 1,
						       SVE_NUM_SLICES - 1);

	/* reg ID ranges for P- registers and FFR (which are contiguous) */
	const u64 preg_id_min = KVM_REG_ARM64_SVE_PREG(0, 0);
	const u64 preg_id_max = KVM_REG_ARM64_SVE_FFR(SVE_NUM_SLICES - 1);

	unsigned int vq;
	unsigned int reg_num;

	unsigned int reqoffset, reqlen; /* User-requested offset and length */
	unsigned int maxlen; /* Maximum permitted length */

	size_t sve_state_size;

	const u64 last_preg_id = KVM_REG_ARM64_SVE_PREG(SVE_NUM_PREGS - 1,
							SVE_NUM_SLICES - 1);

	/* Verify that the P-regs and FFR really do have contiguous IDs: */
	BUILD_BUG_ON(KVM_REG_ARM64_SVE_FFR(0) != last_preg_id + 1);

	/* Verify that we match the UAPI header: */
	BUILD_BUG_ON(SVE_NUM_SLICES != KVM_ARM64_SVE_MAX_SLICES);

	reg_num = (reg->id & SVE_REG_ID_MASK) >> SVE_REG_ID_SHIFT;

	if (reg->id >= zreg_id_min && reg->id <= zreg_id_max) {
		if (!vcpu_has_sve(vcpu) || (reg->id & SVE_REG_SLICE_MASK) > 0)
			return -ENOENT;

		vq = vcpu_sve_max_vq(vcpu);

		reqoffset = SVE_SIG_ZREG_OFFSET(vq, reg_num) -
				SVE_SIG_REGS_OFFSET;
		reqlen = KVM_SVE_ZREG_SIZE;
		maxlen = SVE_SIG_ZREG_SIZE(vq);
	} else if (reg->id >= preg_id_min && reg->id <= preg_id_max) {
		if (!vcpu_has_sve(vcpu) || (reg->id & SVE_REG_SLICE_MASK) > 0)
			return -ENOENT;

		vq = vcpu_sve_max_vq(vcpu);

		reqoffset = SVE_SIG_PREG_OFFSET(vq, reg_num) -
				SVE_SIG_REGS_OFFSET;
		reqlen = KVM_SVE_PREG_SIZE;
		maxlen = SVE_SIG_PREG_SIZE(vq);
	} else {
		return -EINVAL;
	}

	sve_state_size = vcpu_sve_state_size(vcpu);
	if (WARN_ON(!sve_state_size))
		return -EINVAL;

	region->koffset = array_index_nospec(reqoffset, sve_state_size);
	region->klen = min(maxlen, reqlen);
	region->upad = reqlen - region->klen;

	return 0;
}

static int get_sve_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
{
	int ret;
	struct sve_state_reg_region region;
	char __user *uptr = (char __user *)reg->addr;

	/* Handle the KVM_REG_ARM64_SVE_VLS pseudo-reg as a special case: */
	if (reg->id == KVM_REG_ARM64_SVE_VLS)
		return get_sve_vls(vcpu, reg);

	/* Try to interpret reg ID as an architectural SVE register... */
	ret = sve_reg_to_region(&region, vcpu, reg);
	if (ret)

Annotation

Implementation Notes