[Qemu-devel] [PATCH 20/25] s390x/ioinst: Rework memory access in TSCH instruction

[Jens Freimann <jfrei@linux.vnet.ibm.com>]

From: Thomas Huth <thuth@linux.vnet.ibm.com>

Change the TSCH handler to use the new logical memory access functions.
Since the channel should not be updated in case of a protection or access
exception while writing to the guest memory, the css_do_tsch() has to be
split up into two parts, one for retrieving the IRB and one for the update.

Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 hw/s390x/css.c        | 38 +++++++++++++++++++++++---------------
 target-s390x/cpu.h    |  3 ++-
 target-s390x/ioinst.c | 33 +++++++++++++++++++--------------
 3 files changed, 44 insertions(+), 30 deletions(-)

diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index 65e6b71..f6d0c0a 100644
--- a/hw/s390x/css.c
+++ b/hw/s390x/css.c
@@ -801,7 +801,8 @@ out:
     return ret;
 }
 
-static void copy_irb_to_guest(IRB *dest, const IRB *src, PMCW *pmcw)
+static void copy_irb_to_guest(IRB *dest, const IRB *src, PMCW *pmcw,
+                              int *irb_len)
 {
     int i;
     uint16_t stctl = src->scsw.ctrl & SCSW_CTRL_MASK_STCTL;
@@ -815,6 +816,8 @@ static void copy_irb_to_guest(IRB *dest, const IRB *src, PMCW *pmcw)
     for (i = 0; i < ARRAY_SIZE(dest->ecw); i++) {
         dest->ecw[i] = cpu_to_be32(src->ecw[i]);
     }
+    *irb_len = sizeof(*dest) - sizeof(dest->emw);
+
     /* extended measurements enabled? */
     if ((src->scsw.flags & SCSW_FLAGS_MASK_ESWF) ||
         !(pmcw->flags & PMCW_FLAGS_MASK_TF) ||
@@ -832,26 +835,21 @@ static void copy_irb_to_guest(IRB *dest, const IRB *src, PMCW *pmcw)
             dest->emw[i] = cpu_to_be32(src->emw[i]);
         }
     }
+    *irb_len = sizeof(*dest);
 }
 
-int css_do_tsch(SubchDev *sch, IRB *target_irb)
+int css_do_tsch_get_irb(SubchDev *sch, IRB *target_irb, int *irb_len)
 {
     SCSW *s = &sch->curr_status.scsw;
     PMCW *p = &sch->curr_status.pmcw;
     uint16_t stctl;
-    uint16_t fctl;
-    uint16_t actl;
     IRB irb;
-    int ret;
 
     if (!(p->flags & (PMCW_FLAGS_MASK_DNV | PMCW_FLAGS_MASK_ENA))) {
-        ret = 3;
-        goto out;
+        return 3;
     }
 
     stctl = s->ctrl & SCSW_CTRL_MASK_STCTL;
-    fctl = s->ctrl & SCSW_CTRL_MASK_FCTL;
-    actl = s->ctrl & SCSW_CTRL_MASK_ACTL;
 
     /* Prepare the irb for the guest. */
     memset(&irb, 0, sizeof(IRB));
@@ -876,7 +874,22 @@ int css_do_tsch(SubchDev *sch, IRB *target_irb)
         }
     }
     /* Store the irb to the guest. */
-    copy_irb_to_guest(target_irb, &irb, p);
+    copy_irb_to_guest(target_irb, &irb, p, irb_len);
+
+    return ((stctl & SCSW_STCTL_STATUS_PEND) == 0);
+}
+
+void css_do_tsch_update_subch(SubchDev *sch)
+{
+    SCSW *s = &sch->curr_status.scsw;
+    PMCW *p = &sch->curr_status.pmcw;
+    uint16_t stctl;
+    uint16_t fctl;
+    uint16_t actl;
+
+    stctl = s->ctrl & SCSW_CTRL_MASK_STCTL;
+    fctl = s->ctrl & SCSW_CTRL_MASK_FCTL;
+    actl = s->ctrl & SCSW_CTRL_MASK_ACTL;
 
     /* Clear conditions on subchannel, if applicable. */
     if (stctl & SCSW_STCTL_STATUS_PEND) {
@@ -913,11 +926,6 @@ int css_do_tsch(SubchDev *sch, IRB *target_irb)
             memset(sch->sense_data, 0 , sizeof(sch->sense_data));
         }
     }
-
-    ret = ((stctl & SCSW_STCTL_STATUS_PEND) == 0);
-
-out:
-    return ret;
 }
 
 static void copy_crw_to_guest(CRW *dest, const CRW *src)
diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h
index 7180d68..7c07ca6 100644
--- a/target-s390x/cpu.h
+++ b/target-s390x/cpu.h
@@ -455,7 +455,8 @@ int css_do_xsch(SubchDev *sch);
 int css_do_csch(SubchDev *sch);
 int css_do_hsch(SubchDev *sch);
 int css_do_ssch(SubchDev *sch, ORB *orb);
-int css_do_tsch(SubchDev *sch, IRB *irb);
+int css_do_tsch_get_irb(SubchDev *sch, IRB *irb, int *irb_len);
+void css_do_tsch_update_subch(SubchDev *sch);
 int css_do_stcrw(CRW *crw);
 int css_do_tpi(IOIntCode *int_code, int lowcore);
 int css_collect_chp_desc(int m, uint8_t cssid, uint8_t f_chpid, uint8_t l_chpid,
diff --git a/target-s390x/ioinst.c b/target-s390x/ioinst.c
index 8052886..aa55ca8 100644
--- a/target-s390x/ioinst.c
+++ b/target-s390x/ioinst.c
@@ -341,10 +341,9 @@ int ioinst_handle_tsch(S390CPU *cpu, uint64_t reg1, uint32_t ipb)
     CPUS390XState *env = &cpu->env;
     int cssid, ssid, schid, m;
     SubchDev *sch;
-    IRB *irb;
+    IRB irb;
     uint64_t addr;
-    int cc;
-    hwaddr len = sizeof(*irb);
+    int cc, irb_len;
 
     if (ioinst_disassemble_sch_ident(reg1, &m, &cssid, &ssid, &schid)) {
         program_interrupt(env, PGM_OPERAND, 2);
@@ -356,23 +355,29 @@ int ioinst_handle_tsch(S390CPU *cpu, uint64_t reg1, uint32_t ipb)
         program_interrupt(env, PGM_SPECIFICATION, 2);
         return -EIO;
     }
-    irb = s390_cpu_physical_memory_map(env, addr, &len, 1);
-    if (!irb || len != sizeof(*irb)) {
-        program_interrupt(env, PGM_ADDRESSING, 2);
-        cc = -EIO;
-        goto out;
-    }
+
     sch = css_find_subch(m, cssid, ssid, schid);
     if (sch && css_subch_visible(sch)) {
-        cc = css_do_tsch(sch, irb);
-        /* 0 - status pending, 1 - not status pending */
+        cc = css_do_tsch_get_irb(sch, &irb, &irb_len);
     } else {
         cc = 3;
     }
+    /* 0 - status pending, 1 - not status pending, 3 - not operational */
+    if (cc != 3) {
+        if (s390_cpu_virt_mem_write(cpu, addr, &irb, irb_len) != 0) {
+            return -EFAULT;
+        }
+        css_do_tsch_update_subch(sch);
+    } else {
+        irb_len = sizeof(irb) - sizeof(irb.emw);
+        /* Access exceptions have a higher priority than cc3 */
+        if (s390_cpu_virt_mem_check_write(cpu, addr, irb_len) != 0) {
+            return -EFAULT;
+        }
+    }
+
     setcc(cpu, cc);
-out:
-    s390_cpu_physical_memory_unmap(env, irb, sizeof(*irb), 1);
-    return cc;
+    return 0;
 }
 
 typedef struct ChscReq {
-- 
2.1.4