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KVM: S390: protvirt: Introduce instruction data area bounce buffer 

Now that we can't access guest memory anymore, we have a dedicated
satellite block that's a bounce buffer for instruction data.

We re-use the memop interface to copy the instruction data to / from
userspace. This lets us re-use a lot of QEMU code which used that
interface to make logical guest memory accesses which are not possible
anymore in protected mode anyway.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
[borntraeger@de.ibm.com: patch merging, splitting, fixing]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
Janosch Frank 2019-04-02 09:21:06 +02:00 committed by Christian Borntraeger
parent c8aac2344d
commit 19e1227768
4 changed files with 91 additions and 11 deletions
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11
arch/s390/include/asm/kvm_host.h
View File

@ -127,6 +127,12 @@ struct mcck_volatile_info {
#define CR14_INITIAL_MASK (CR14_UNUSED_32 | CR14_UNUSED_33 | \
CR14_EXTERNAL_DAMAGE_SUBMASK)
#define SIDAD_SIZE_MASK 0xff
#define sida_origin(sie_block) \
((sie_block)->sidad & PAGE_MASK)
#define sida_size(sie_block) \
((((sie_block)->sidad & SIDAD_SIZE_MASK) + 1) * PAGE_SIZE)
#define CPUSTAT_STOPPED 0x80000000
#define CPUSTAT_WAIT 0x10000000
#define CPUSTAT_ECALL_PEND 0x08000000
@ -315,7 +321,10 @@ struct kvm_s390_sie_block {
#define CRYCB_FORMAT2 0x00000003
__u32 crycbd; /* 0x00fc */
__u64 gcr[16]; /* 0x0100 */
__u64 gbea; /* 0x0180 */
union {
__u64 gbea; /* 0x0180 */
__u64 sidad;
};
__u8 reserved188[8]; /* 0x0188 */
__u64 sdnxo; /* 0x0190 */
__u8 reserved198[8]; /* 0x0198 */

66
arch/s390/kvm/kvm-s390.c
View File

@ -4495,12 +4495,40 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
return r;
}
static long kvm_s390_guest_sida_op(struct kvm_vcpu *vcpu,
struct kvm_s390_mem_op *mop)
{
void __user *uaddr = (void __user *)mop->buf;
int r = 0;
if (mop->flags || !mop->size)
return -EINVAL;
if (mop->size + mop->sida_offset < mop->size)
return -EINVAL;
if (mop->size + mop->sida_offset > sida_size(vcpu->arch.sie_block))
return -E2BIG;
switch (mop->op) {
case KVM_S390_MEMOP_SIDA_READ:
if (copy_to_user(uaddr, (void *)(sida_origin(vcpu->arch.sie_block) +
mop->sida_offset), mop->size))
r = -EFAULT;
break;
case KVM_S390_MEMOP_SIDA_WRITE:
if (copy_from_user((void *)(sida_origin(vcpu->arch.sie_block) +
mop->sida_offset), uaddr, mop->size))
r = -EFAULT;
break;
}
return r;
}
static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu,
struct kvm_s390_mem_op *mop)
{
void __user *uaddr = (void __user *)mop->buf;
void *tmpbuf = NULL;
int r, srcu_idx;
int r = 0;
const u64 supported_flags = KVM_S390_MEMOP_F_INJECT_EXCEPTION
| KVM_S390_MEMOP_F_CHECK_ONLY;
@ -4510,14 +4538,15 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu,
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_CHECK_ONLY)) {
tmpbuf = vmalloc(mop->size);
if (!tmpbuf)
return -ENOMEM;
}
srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
switch (mop->op) {
case KVM_S390_MEMOP_LOGICAL_READ:
if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY) {
@ -4543,12 +4572,8 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu,
}
r = write_guest(vcpu, mop->gaddr, mop->ar, tmpbuf, mop->size);
break;
default:
r = -EINVAL;
}
srcu_read_unlock(&vcpu->kvm->srcu, srcu_idx);
if (r > 0 && (mop->flags & KVM_S390_MEMOP_F_INJECT_EXCEPTION) != 0)
kvm_s390_inject_prog_irq(vcpu, &vcpu->arch.pgm);
@ -4556,6 +4581,31 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu,
return r;
}
static long kvm_s390_guest_memsida_op(struct kvm_vcpu *vcpu,
struct kvm_s390_mem_op *mop)
{
int r, srcu_idx;
srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
switch (mop->op) {
case KVM_S390_MEMOP_LOGICAL_READ:
case KVM_S390_MEMOP_LOGICAL_WRITE:
r = kvm_s390_guest_mem_op(vcpu, mop);
break;
case KVM_S390_MEMOP_SIDA_READ:
case KVM_S390_MEMOP_SIDA_WRITE:
/* we are locked against sida going away by the vcpu->mutex */
r = kvm_s390_guest_sida_op(vcpu, mop);
break;
default:
r = -EINVAL;
}
srcu_read_unlock(&vcpu->kvm->srcu, srcu_idx);
return r;
}
long kvm_arch_vcpu_async_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
@ -4686,7 +4736,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
struct kvm_s390_mem_op mem_op;
if (copy_from_user(&mem_op, argp, sizeof(mem_op)) == 0)
r = kvm_s390_guest_mem_op(vcpu, &mem_op);
r = kvm_s390_guest_memsida_op(vcpu, &mem_op);
else
r = -EFAULT;
break;

16
arch/s390/kvm/pv.c
View File

@ -33,10 +33,18 @@ int kvm_s390_pv_destroy_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc)
if (!cc)
free_pages(vcpu->arch.pv.stor_base,
get_order(uv_info.guest_cpu_stor_len));
free_page(sida_origin(vcpu->arch.sie_block));
vcpu->arch.sie_block->pv_handle_cpu = 0;
vcpu->arch.sie_block->pv_handle_config = 0;
memset(&vcpu->arch.pv, 0, sizeof(vcpu->arch.pv));
vcpu->arch.sie_block->sdf = 0;
/*
* The sidad field (for sdf == 2) is now the gbea field (for sdf == 0).
* Use the reset value of gbea to avoid leaking the kernel pointer of
* the just freed sida.
*/
vcpu->arch.sie_block->gbea = 1;
kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
return cc ? EIO : 0;
@ -64,6 +72,14 @@ int kvm_s390_pv_create_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc)
uvcb.state_origin = (u64)vcpu->arch.sie_block;
uvcb.stor_origin = (u64)vcpu->arch.pv.stor_base;
/* Alloc Secure Instruction Data Area Designation */
vcpu->arch.sie_block->sidad = __get_free_page(GFP_KERNEL | __GFP_ZERO);
if (!vcpu->arch.sie_block->sidad) {
free_pages(vcpu->arch.pv.stor_base,
get_order(uv_info.guest_cpu_stor_len));
return -ENOMEM;
}
cc = uv_call(0, (u64)&uvcb);
*rc = uvcb.header.rc;
*rrc = uvcb.header.rrc;

9
include/uapi/linux/kvm.h
View File

@ -474,12 +474,17 @@ struct kvm_s390_mem_op {
__u32 size; /* amount of bytes */
__u32 op; /* type of operation */
__u64 buf; /* buffer in userspace */
__u8 ar; /* the access register number */
__u8 reserved[31]; /* should be set to 0 */
union {
__u8 ar; /* the access register number */
__u32 sida_offset; /* offset into the sida */
__u8 reserved[32]; /* should be set to 0 */
};
};
/* types for kvm_s390_mem_op->op */
#define KVM_S390_MEMOP_LOGICAL_READ 0
#define KVM_S390_MEMOP_LOGICAL_WRITE 1
#define KVM_S390_MEMOP_SIDA_READ 2
#define KVM_S390_MEMOP_SIDA_WRITE 3
/* 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)