[PATCH v10 12/16] s390x: protvirt: Disable address checks for PV guest IO emulation

[Janosch Frank <frankja@linux.ibm.com>]

IO instruction data is routed through SIDAD for protected guests, so
adresses do not need to be checked, as this is kernel memory which is
always available.

Also the instruction data always starts at offset 0 of the SIDAD.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
---
 target/s390x/ioinst.c | 35 ++++++++++++++++++++++++++++-------
 1 file changed, 28 insertions(+), 7 deletions(-)

diff --git a/target/s390x/ioinst.c b/target/s390x/ioinst.c
index 0e840cc5792afe02..8828482eec306a2b 100644
--- a/target/s390x/ioinst.c
+++ b/target/s390x/ioinst.c
@@ -16,6 +16,25 @@
 #include "hw/s390x/ioinst.h"
 #include "trace.h"
 #include "hw/s390x/s390-pci-bus.h"
+#include "hw/s390x/pv.h"
+
+/* All I/O instructions but chsc use the s format */
+static uint64_t get_address_from_regs(CPUS390XState *env, uint32_t ipb,
+                                      uint8_t *ar)
+{
+    /*
+     * Addresses for protected guests are all offsets into the
+     * satellite block which holds the IO control structures. Those
+     * control structures are always starting at offset 0 and are
+     * always aligned and accessible. So we can return 0 here which
+     * will pass the following address checks.
+     */
+    if (s390_is_pv()) {
+        *ar = 0;
+        return 0;
+    }
+    return decode_basedisp_s(env, ipb, ar);
+}
 
 int ioinst_disassemble_sch_ident(uint32_t value, int *m, int *cssid, int *ssid,
                                  int *schid)
@@ -114,7 +133,7 @@ void ioinst_handle_msch(S390CPU *cpu, uint64_t reg1, uint32_t ipb, uintptr_t ra)
     CPUS390XState *env = &cpu->env;
     uint8_t ar;
 
-    addr = decode_basedisp_s(env, ipb, &ar);
+    addr = get_address_from_regs(env, ipb, &ar);
     if (addr & 3) {
         s390_program_interrupt(env, PGM_SPECIFICATION, ra);
         return;
@@ -171,7 +190,7 @@ void ioinst_handle_ssch(S390CPU *cpu, uint64_t reg1, uint32_t ipb, uintptr_t ra)
     CPUS390XState *env = &cpu->env;
     uint8_t ar;
 
-    addr = decode_basedisp_s(env, ipb, &ar);
+    addr = get_address_from_regs(env, ipb, &ar);
     if (addr & 3) {
         s390_program_interrupt(env, PGM_SPECIFICATION, ra);
         return;
@@ -203,7 +222,7 @@ void ioinst_handle_stcrw(S390CPU *cpu, uint32_t ipb, uintptr_t ra)
     CPUS390XState *env = &cpu->env;
     uint8_t ar;
 
-    addr = decode_basedisp_s(env, ipb, &ar);
+    addr = get_address_from_regs(env, ipb, &ar);
     if (addr & 3) {
         s390_program_interrupt(env, PGM_SPECIFICATION, ra);
         return;
@@ -234,7 +253,7 @@ void ioinst_handle_stsch(S390CPU *cpu, uint64_t reg1, uint32_t ipb,
     CPUS390XState *env = &cpu->env;
     uint8_t ar;
 
-    addr = decode_basedisp_s(env, ipb, &ar);
+    addr = get_address_from_regs(env, ipb, &ar);
     if (addr & 3) {
         s390_program_interrupt(env, PGM_SPECIFICATION, ra);
         return;
@@ -303,7 +322,7 @@ int ioinst_handle_tsch(S390CPU *cpu, uint64_t reg1, uint32_t ipb, uintptr_t ra)
         return -EIO;
     }
     trace_ioinst_sch_id("tsch", cssid, ssid, schid);
-    addr = decode_basedisp_s(env, ipb, &ar);
+    addr = get_address_from_regs(env, ipb, &ar);
     if (addr & 3) {
         s390_program_interrupt(env, PGM_SPECIFICATION, ra);
         return -EIO;
@@ -601,7 +620,7 @@ void ioinst_handle_chsc(S390CPU *cpu, uint32_t ipb, uintptr_t ra)
 {
     ChscReq *req;
     ChscResp *res;
-    uint64_t addr;
+    uint64_t addr = 0;
     int reg;
     uint16_t len;
     uint16_t command;
@@ -610,7 +629,9 @@ void ioinst_handle_chsc(S390CPU *cpu, uint32_t ipb, uintptr_t ra)
 
     trace_ioinst("chsc");
     reg = (ipb >> 20) & 0x00f;
-    addr = env->regs[reg];
+    if (!s390_is_pv()) {
+        addr = env->regs[reg];
+    }
     /* Page boundary? */
     if (addr & 0xfff) {
         s390_program_interrupt(env, PGM_SPECIFICATION, ra);
-- 
2.25.1