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[PATCH v8 11/15] s390x: protvirt: Disable address checks for PV guest IO


From: Janosch Frank
Subject: [PATCH v8 11/15] s390x: protvirt: Disable address checks for PV guest IO emulation
Date: Tue, 10 Mar 2020 09:40:04 -0400

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

Signed-off-by: Janosch Frank <address@hidden>
Reviewed-by: Thomas Huth <address@hidden>
Reviewed-by: David Hildenbrand <address@hidden>
---
 target/s390x/ioinst.c | 32 +++++++++++++++++++++++++-------
 1 file changed, 25 insertions(+), 7 deletions(-)

diff --git a/target/s390x/ioinst.c b/target/s390x/ioinst.c
index c437a1d8c6..34afd2ee64 100644
--- a/target/s390x/ioinst.c
+++ b/target/s390x/ioinst.c
@@ -17,6 +17,22 @@
 #include "trace.h"
 #include "hw/s390x/s390-pci-bus.h"
 
+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 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 +130,7 @@ 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 +187,7 @@ 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 +219,7 @@ 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 +250,7 @@ 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 +319,7 @@ 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 +617,7 @@ 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 +626,9 @@ 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);
-- 
2.20.1




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