Commit e9e9feeb authored by Janis Schoetterl-Glausch's avatar Janis Schoetterl-Glausch Committed by Christian Borntraeger
Browse files

KVM: s390: Add optional storage key checking to MEMOP IOCTL 



User space needs a mechanism to perform key checked accesses when
emulating instructions.

The key can be passed as an additional argument.
Having an additional argument is flexible, as user space can
pass the guest PSW's key, in order to make an access the same way the
CPU would, or pass another key if necessary.

Signed-off-by: default avatarJanis Schoetterl-Glausch <scgl@linux.ibm.com>
Reviewed-by: default avatarClaudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: default avatarChristian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: default avatarJanosch Frank <frankja@linux.ibm.com>
Link: https://lore.kernel.org/r/20220211182215.2730017-6-scgl@linux.ibm.com


Signed-off-by: default avatarChristian Borntraeger <borntraeger@linux.ibm.com>
parent c7ef9ebb

arch/s390/kvm/kvm-s390.c

+21 −10
Original line number Diff line number Diff line
@@ -2359,6 +2359,11 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd) 
	return r;

}



static bool access_key_invalid(u8 access_key)

{

	return access_key > 0xf;

}



long kvm_arch_vm_ioctl(struct file *filp,

		       unsigned int ioctl, unsigned long arg)

{
@@ -4692,17 +4697,21 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu, 
	void *tmpbuf = NULL;

	int r = 0;

	const u64 supported_flags = KVM_S390_MEMOP_F_INJECT_EXCEPTION

				    | KVM_S390_MEMOP_F_CHECK_ONLY;

				    | KVM_S390_MEMOP_F_CHECK_ONLY

				    | KVM_S390_MEMOP_F_SKEY_PROTECTION;



	if (mop->flags & ~supported_flags || mop->ar >= NUM_ACRS || !mop->size)

		return -EINVAL;



	if (mop->size > MEM_OP_MAX_SIZE)

		return -E2BIG;



	if (kvm_s390_pv_cpu_is_protected(vcpu))

		return -EINVAL;



	if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {

		if (access_key_invalid(mop->key))

			return -EINVAL;

	} else {

		mop->key = 0;

	}

	if (!(mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)) {

		tmpbuf = vmalloc(mop->size);

		if (!tmpbuf)
@@ -4712,11 +4721,12 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu, 
	switch (mop->op) {

	case KVM_S390_MEMOP_LOGICAL_READ:

		if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY) {

			r = check_gva_range(vcpu, mop->gaddr, mop->ar,

					    mop->size, GACC_FETCH, 0);

			r = check_gva_range(vcpu, mop->gaddr, mop->ar, mop->size,

					    GACC_FETCH, mop->key);

			break;

		}

		r = read_guest(vcpu, mop->gaddr, mop->ar, tmpbuf, mop->size);

		r = read_guest_with_key(vcpu, mop->gaddr, mop->ar, tmpbuf,

					mop->size, mop->key);

		if (r == 0) {

			if (copy_to_user(uaddr, tmpbuf, mop->size))

				r = -EFAULT;
@@ -4724,15 +4734,16 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu, 
		break;

	case KVM_S390_MEMOP_LOGICAL_WRITE:

		if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY) {

			r = check_gva_range(vcpu, mop->gaddr, mop->ar,

					    mop->size, GACC_STORE, 0);

			r = check_gva_range(vcpu, mop->gaddr, mop->ar, mop->size,

					    GACC_STORE, mop->key);

			break;

		}

		if (copy_from_user(tmpbuf, uaddr, mop->size)) {

			r = -EFAULT;

			break;

		}

		r = write_guest(vcpu, mop->gaddr, mop->ar, tmpbuf, mop->size);

		r = write_guest_with_key(vcpu, mop->gaddr, mop->ar, tmpbuf,

					 mop->size, mop->key);

		break;

	}

include/uapi/linux/kvm.h

+5 −1
Original line number Diff line number Diff line
@@ -562,7 +562,10 @@ struct kvm_s390_mem_op { 
	__u32 op;		/* type of operation */

	__u64 buf;		/* buffer in userspace */

	union {

		struct {

			__u8 ar;	/* the access register number */

			__u8 key;	/* access key, ignored if flag unset */

		};

		__u32 sida_offset; /* offset into the sida */

		__u8 reserved[32]; /* should be set to 0 */

	};
@@ -575,6 +578,7 @@ struct kvm_s390_mem_op { 
/* flags for kvm_s390_mem_op->flags */

#define KVM_S390_MEMOP_F_CHECK_ONLY		(1ULL << 0)

#define KVM_S390_MEMOP_F_INJECT_EXCEPTION	(1ULL << 1)

#define KVM_S390_MEMOP_F_SKEY_PROTECTION	(1ULL << 2)



/* for KVM_INTERRUPT */

struct kvm_interrupt {