Now that we can't access guest memory anymore, we have a dedicated
sattelite 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@xxxxxxxxxxxxx>
---
arch/s390/include/asm/kvm_host.h | 5 ++++-
arch/s390/kvm/kvm-s390.c | 31 +++++++++++++++++++++++++++++++
arch/s390/kvm/pv.c | 9 +++++++++
3 files changed, 44 insertions(+), 1 deletion(-)
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 5deabf9734d9..2a8a1e21e1c3 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -308,7 +308,10 @@ 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 */
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 97d3a81e5074..6747cb6cf062 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -4416,6 +4416,13 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu,
if (mop->size > MEM_OP_MAX_SIZE)
return -E2BIG;
+ /* Protected guests move instruction data over the satellite
+ * block which has its own size limit
+ */
+ if (kvm_s390_pv_is_protected(vcpu->kvm) &&
+ mop->size > ((vcpu->arch.sie_block->sidad & 0x0f) + 1) * PAGE_SIZE)
+ return -E2BIG;
+
if (!(mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)) {
tmpbuf = vmalloc(mop->size);
if (!tmpbuf)
@@ -4427,10 +4434,22 @@ 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) {
+ if (kvm_s390_pv_is_protected(vcpu->kvm)) {
+ r = 0;
+ break;
+ }
r = check_gva_range(vcpu, mop->gaddr, mop->ar,
mop->size, GACC_FETCH);
break;
}
+ if (kvm_s390_pv_is_protected(vcpu->kvm)) {
+ r = 0;
+ if (copy_to_user(uaddr, (void *)vcpu->arch.sie_block->sidad +
+ (mop->gaddr & ~PAGE_MASK),
+ mop->size))
+ r = -EFAULT;
+ break;
+ }
r = read_guest(vcpu, mop->gaddr, mop->ar, tmpbuf, mop->size);
if (r == 0) {
if (copy_to_user(uaddr, tmpbuf, mop->size))
@@ -4439,10 +4458,22 @@ 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) {
+ if (kvm_s390_pv_is_protected(vcpu->kvm)) {
+ r = 0;
+ break;
+ }
r = check_gva_range(vcpu, mop->gaddr, mop->ar,
mop->size, GACC_STORE);
break;
}
+ if (kvm_s390_pv_is_protected(vcpu->kvm)) {
+ r = 0;
+ if (copy_from_user((void *)vcpu->arch.sie_block->sidad +
+ (mop->gaddr & ~PAGE_MASK), uaddr,
+ mop->size))
+ r = -EFAULT;
+ break;
+ }
if (copy_from_user(tmpbuf, uaddr, mop->size)) {
r = -EFAULT;
break;
diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index 383e660e2221..be7d558ab897 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -119,6 +119,7 @@ int kvm_s390_pv_destroy_cpu(struct kvm_vcpu *vcpu)
free_pages(vcpu->arch.pv.stor_base,
get_order(uv_info.guest_cpu_stor_len));
+ free_page(vcpu->arch.sie_block->sidad);
/* Clear cpu and vm handle */
memset(&vcpu->arch.sie_block->reserved10, 0,
sizeof(vcpu->arch.sie_block->reserved10));
@@ -150,6 +151,14 @@ int kvm_s390_pv_create_cpu(struct kvm_vcpu *vcpu)
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;
+ }
+
rc = uv_call(0, (u64)&uvcb);
VCPU_EVENT(vcpu, 3, "PROTVIRT CREATE VCPU: cpu %d handle %llx rc %x rrc %x",
vcpu->vcpu_id, uvcb.cpu_handle, uvcb.header.rc,
--
2.20.1
