[PATCH v1 0/3] target/s390x - DIAG 308 extend subcode 10 to return UVC cmd id, RC and RRC values upon failure to enter secure mode

[PATCH v1 0/3] target/s390x - DIAG 308 extend subcode 10 to return UVC cmd id, RC and RRC values upon failure to enter secure mode

[Gautam Gala]

DIAG 308 (subcode 10 - performing secure execution unpack) response
code when the configuration is unable to enter secure mode has limited
usability as it is a fixed value (0xa02) for variety of different
reasons. The aim is to extend this DIAG to return UVC command ID, RC
and RRC values in addition to the diag response code. This feature can
be used by the stage3a bootloader (s390-tools/rust/pvimg/boot) to read
these new values from the corresponding register and print an
appropriate error message to help pin point the cause.

The response code, UVC RC, RRC, and command ID are returned in bit
positions 48-63, 32-47, 16-31, and 0-15 of register R1 + 1 if the
function does not complete successfully (Previously, only the
response code was returned in bits 48-63).

Gautam Gala (3):
  target/s390x: Introduce constant when checking if PV header couldn't
    be decrypted
  target/s390x: introduce function when exiting PV
  target/s390x: Return UVC cmd code, RC and RRC value when DIAG 308
    Subcode 10 fails to enter secure mode

 hw/s390x/ipl.c             | 11 ++++---
 hw/s390x/ipl.h             |  5 +--
 hw/s390x/s390-virtio-ccw.c | 24 +++++++++++----
 target/s390x/kvm/pv.c      | 62 ++++++++++++++++++++++++--------------
 target/s390x/kvm/pv.h      | 27 ++++++++++++-----
 5 files changed, 86 insertions(+), 43 deletions(-)

-- 
2.49.0

[PATCH v1 1/3] target/s390x: Introduce constant when checking if PV header couldn't be decrypted

[Gautam Gala]

Introduce a named constant when checking the Set Secure Configuration parameters
UV call return code for the case where no valid host key was found and therefore
the PV header couldn't be decrypted (0x108).

Signed-off-by: Gautam Gala <ggala@linux.ibm.com>
---
 target/s390x/kvm/pv.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/target/s390x/kvm/pv.c b/target/s390x/kvm/pv.c
index b191a4a68a..3a0a971f0b 100644
--- a/target/s390x/kvm/pv.c
+++ b/target/s390x/kvm/pv.c
@@ -147,6 +147,7 @@ bool s390_pv_vm_try_disable_async(S390CcwMachineState *ms)
     return true;
 }
 
+#define DIAG_308_UV_RC_INVAL_HOSTKEY    0x0108
 int s390_pv_set_sec_parms(uint64_t origin, uint64_t length, Error **errp)
 {
     int ret, pvrc;
@@ -158,7 +159,7 @@ int s390_pv_set_sec_parms(uint64_t origin, uint64_t length, Error **errp)
     ret = s390_pv_cmd_pvrc(KVM_PV_SET_SEC_PARMS, &args, &pvrc);
     if (ret) {
         error_setg(errp, "Failed to set secure execution parameters");
-        if (pvrc == 0x108) {
+        if (pvrc == DIAG_308_UV_RC_INVAL_HOSTKEY) {
             error_append_hint(errp, "Please check whether the image is "
                                     "correctly encrypted for this host\n");
         }
-- 
2.49.0

[PATCH v1 2/3] target/s390x: introduce function when exiting PV

[Gautam Gala]

introduce a static function when exiting PV. The function replaces an
existing macro (s390_pv_cmd_exit).

Signed-off-by: Gautam Gala <ggala@linux.ibm.com>
---
 target/s390x/kvm/pv.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/target/s390x/kvm/pv.c b/target/s390x/kvm/pv.c
index 3a0a971f0b..b4abda2cef 100644
--- a/target/s390x/kvm/pv.c
+++ b/target/s390x/kvm/pv.c
@@ -59,14 +59,15 @@ static int __s390_pv_cmd(uint32_t cmd, const char *cmdname, void *data,
  */
 #define s390_pv_cmd(cmd, data) __s390_pv_cmd(cmd, #cmd, data, NULL)
 #define s390_pv_cmd_pvrc(cmd, data, pvrc) __s390_pv_cmd(cmd, #cmd, data, pvrc)
-#define s390_pv_cmd_exit(cmd, data)    \
-{                                      \
-    int rc;                            \
-                                       \
-    rc = __s390_pv_cmd(cmd, #cmd, data, NULL); \
-    if (rc) {                          \
-        exit(1);                       \
-    }                                  \
+
+static void s390_pv_cmd_exit(uint32_t cmd, void *data)
+{
+    int rc;
+
+    rc = s390_pv_cmd(cmd, data);
+    if (rc) {
+        exit(1);
+    }
 }
 
 int s390_pv_query_info(void)
-- 
2.49.0

[PATCH v1 3/3] target/s390x: Return UVC cmd code, RC and RRC value when DIAG 308 Subcode 10 fails to enter secure mode

[Gautam Gala]

Extend DIAG308 subcode 10 to return the UVC RC, RRC and command code
in bit positions 32-47, 16-31, and 0-15 of register R1 + 1 if the
function does not complete successfully (in addition to the
previously returned diag response code in bit position 47-63).

Signed-off-by: Gautam Gala <ggala@linux.ibm.com>
---
 hw/s390x/ipl.c             | 11 ++++++----
 hw/s390x/ipl.h             |  5 +++--
 hw/s390x/s390-virtio-ccw.c | 24 +++++++++++++++------
 target/s390x/kvm/pv.c      | 44 +++++++++++++++++++++++++-------------
 target/s390x/kvm/pv.h      | 27 ++++++++++++++++-------
 5 files changed, 76 insertions(+), 35 deletions(-)

diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
index ce6f6078d7..4f3e3945f1 100644
--- a/hw/s390x/ipl.c
+++ b/hw/s390x/ipl.c
@@ -676,7 +676,8 @@ static void s390_ipl_prepare_qipl(S390CPU *cpu)
     cpu_physical_memory_unmap(addr, len, 1, len);
 }
 
-int s390_ipl_prepare_pv_header(Error **errp)
+int s390_ipl_prepare_pv_header(Error **errp, uint16_t *pv_cmd,
+                               uint16_t *pv_rc, uint16_t *pv_rrc)
 {
     IplParameterBlock *ipib = s390_ipl_get_iplb_pv();
     IPLBlockPV *ipib_pv = &ipib->pv;
@@ -685,12 +686,13 @@ int s390_ipl_prepare_pv_header(Error **errp)
 
     cpu_physical_memory_read(ipib_pv->pv_header_addr, hdr,
                              ipib_pv->pv_header_len);
-    rc = s390_pv_set_sec_parms((uintptr_t)hdr, ipib_pv->pv_header_len, errp);
+    rc = s390_pv_set_sec_parms((uintptr_t)hdr, ipib_pv->pv_header_len,
+                               errp, pv_cmd, pv_rc, pv_rrc);
     g_free(hdr);
     return rc;
 }
 
-int s390_ipl_pv_unpack(void)
+int s390_ipl_pv_unpack(uint16_t *pv_cmd, uint16_t *pv_rc, uint16_t *pv_rrc)
 {
     IplParameterBlock *ipib = s390_ipl_get_iplb_pv();
     IPLBlockPV *ipib_pv = &ipib->pv;
@@ -699,7 +701,8 @@ int s390_ipl_pv_unpack(void)
     for (i = 0; i < ipib_pv->num_comp; i++) {
         rc = s390_pv_unpack(ipib_pv->components[i].addr,
                             TARGET_PAGE_ALIGN(ipib_pv->components[i].size),
-                            ipib_pv->components[i].tweak_pref);
+                            ipib_pv->components[i].tweak_pref,
+                            pv_cmd, pv_rc, pv_rrc);
         if (rc) {
             break;
         }
diff --git a/hw/s390x/ipl.h b/hw/s390x/ipl.h
index 8e3882d506..e021b2431f 100644
--- a/hw/s390x/ipl.h
+++ b/hw/s390x/ipl.h
@@ -26,8 +26,9 @@ void s390_ipl_convert_loadparm(char *ascii_lp, uint8_t *ebcdic_lp);
 void s390_ipl_fmt_loadparm(uint8_t *loadparm, char *str, Error **errp);
 void s390_rebuild_iplb(uint16_t index, IplParameterBlock *iplb);
 void s390_ipl_update_diag308(IplParameterBlock *iplb);
-int s390_ipl_prepare_pv_header(Error **errp);
-int s390_ipl_pv_unpack(void);
+int s390_ipl_prepare_pv_header(Error **errp, uint16_t *pv_cmd,
+                               uint16_t *pv_rc, uint16_t *pv_rrc);
+int s390_ipl_pv_unpack(uint16_t *pv_cmd, uint16_t *pv_rc, uint16_t *pv_rrc);
 void s390_ipl_prepare_cpu(S390CPU *cpu);
 IplParameterBlock *s390_ipl_get_iplb(void);
 IplParameterBlock *s390_ipl_get_iplb_pv(void);
diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index d9e683c5b4..0faf2841d6 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -53,6 +53,13 @@
 
 static Error *pv_mig_blocker;
 
+struct diag308response {
+    uint16_t pv_cmd;
+    uint16_t pv_rrc;
+    uint16_t pv_rc;
+    uint16_t diag_rc;
+};
+
 static S390CPU *s390x_new_cpu(const char *typename, uint32_t core_id,
                               Error **errp)
 {
@@ -364,7 +371,10 @@ static void s390_machine_unprotect(S390CcwMachineState *ms)
     ram_block_discard_disable(false);
 }
 
-static int s390_machine_protect(S390CcwMachineState *ms)
+static int s390_machine_protect(S390CcwMachineState *ms,
+                                uint16_t *pv_cmd,
+                                uint16_t *pv_rc,
+                                uint16_t *pv_rrc)
 {
     Error *local_err = NULL;
     int rc;
@@ -407,19 +417,19 @@ static int s390_machine_protect(S390CcwMachineState *ms)
     }
 
     /* Set SE header and unpack */
-    rc = s390_ipl_prepare_pv_header(&local_err);
+    rc = s390_ipl_prepare_pv_header(&local_err, pv_cmd, pv_rc, pv_rrc);
     if (rc) {
         goto out_err;
     }
 
     /* Decrypt image */
-    rc = s390_ipl_pv_unpack();
+    rc = s390_ipl_pv_unpack(pv_cmd, pv_rc, pv_rrc);
     if (rc) {
         goto out_err;
     }
 
     /* Verify integrity */
-    rc = s390_pv_verify();
+    rc = s390_pv_verify(pv_cmd, pv_rc, pv_rrc);
     if (rc) {
         goto out_err;
     }
@@ -452,6 +462,7 @@ static void s390_machine_reset(MachineState *machine, ResetType type)
 {
     S390CcwMachineState *ms = S390_CCW_MACHINE(machine);
     enum s390_reset reset_type;
+    struct diag308response resp;
     CPUState *cs, *t;
     S390CPU *cpu;
 
@@ -539,8 +550,9 @@ static void s390_machine_reset(MachineState *machine, ResetType type)
         }
         run_on_cpu(cs, s390_do_cpu_reset, RUN_ON_CPU_NULL);
 
-        if (s390_machine_protect(ms)) {
-            s390_pv_inject_reset_error(cs);
+        if (s390_machine_protect(ms, &resp.pv_cmd, &resp.pv_rc, &resp.pv_rrc)) {
+            resp.diag_rc = DIAG_308_RC_INVAL_FOR_PV;
+            s390_pv_inject_reset_error(cs, (uint64_t *)(&resp));
             /*
              * Continue after the diag308 so the guest knows something
              * went wrong.
diff --git a/target/s390x/kvm/pv.c b/target/s390x/kvm/pv.c
index b4abda2cef..3c69f6e74b 100644
--- a/target/s390x/kvm/pv.c
+++ b/target/s390x/kvm/pv.c
@@ -30,7 +30,7 @@ static struct kvm_s390_pv_info_vm info_vm;
 static struct kvm_s390_pv_info_dump info_dump;
 
 static int __s390_pv_cmd(uint32_t cmd, const char *cmdname, void *data,
-                         int *pvrc)
+                         uint16_t *pv_rc, uint16_t *pv_rrc)
 {
     struct kvm_pv_cmd pv_cmd = {
         .cmd = cmd,
@@ -47,9 +47,13 @@ static int __s390_pv_cmd(uint32_t cmd, const char *cmdname, void *data,
                      "IOCTL rc: %d", cmd, cmdname, pv_cmd.rc, pv_cmd.rrc,
                      rc);
     }
-    if (pvrc) {
-        *pvrc = pv_cmd.rc;
+    if (pv_rc) {
+        *pv_rc = pv_cmd.rc;
     }
+    if (pv_rrc) {
+        *pv_rrc = pv_cmd.rrc;
+    }
+
     return rc;
 }
 
@@ -57,8 +61,11 @@ static int __s390_pv_cmd(uint32_t cmd, const char *cmdname, void *data,
  * This macro lets us pass the command as a string to the function so
  * we can print it on an error.
  */
-#define s390_pv_cmd(cmd, data) __s390_pv_cmd(cmd, #cmd, data, NULL)
-#define s390_pv_cmd_pvrc(cmd, data, pvrc) __s390_pv_cmd(cmd, #cmd, data, pvrc)
+#define s390_pv_cmd(cmd, data)  __s390_pv_cmd(cmd, #cmd, data, NULL, NULL)
+#define s390_pv_cmd_pvrc(cmd, data, pv_rc) \
+                                __s390_pv_cmd(cmd, #cmd, data, pv_rc, NULL)
+#define s390_pv_cmd_pvrc_pvrrc(cmd, data, pv_rc, pv_rrc) \
+                                __s390_pv_cmd(cmd, #cmd, data, pv_rc, pv_rrc)
 
 static void s390_pv_cmd_exit(uint32_t cmd, void *data)
 {
@@ -149,18 +156,21 @@ bool s390_pv_vm_try_disable_async(S390CcwMachineState *ms)
 }
 
 #define DIAG_308_UV_RC_INVAL_HOSTKEY    0x0108
-int s390_pv_set_sec_parms(uint64_t origin, uint64_t length, Error **errp)
+int s390_pv_set_sec_parms(uint64_t origin, uint64_t length,
+                          Error **errp, uint16_t *pv_cmd,
+                          uint16_t *pv_rc, uint16_t *pv_rrc)
 {
-    int ret, pvrc;
+    int ret;
     struct kvm_s390_pv_sec_parm args = {
         .origin = origin,
         .length = length,
     };
 
-    ret = s390_pv_cmd_pvrc(KVM_PV_SET_SEC_PARMS, &args, &pvrc);
+    *pv_cmd = KVM_PV_SET_SEC_PARMS;
+    ret = s390_pv_cmd_pvrc_pvrrc(*pv_cmd, &args, pv_rc, pv_rrc);
     if (ret) {
         error_setg(errp, "Failed to set secure execution parameters");
-        if (pvrc == DIAG_308_UV_RC_INVAL_HOSTKEY) {
+        if (*pv_rc == DIAG_308_UV_RC_INVAL_HOSTKEY) {
             error_append_hint(errp, "Please check whether the image is "
                                     "correctly encrypted for this host\n");
         }
@@ -172,7 +182,9 @@ int s390_pv_set_sec_parms(uint64_t origin, uint64_t length, Error **errp)
 /*
  * Called for each component in the SE type IPL parameter block 0.
  */
-int s390_pv_unpack(uint64_t addr, uint64_t size, uint64_t tweak)
+int s390_pv_unpack(uint64_t addr, uint64_t size,
+                   uint64_t tweak, uint16_t *pv_cmd,
+                   uint16_t *pv_rc, uint16_t *pv_rrc)
 {
     struct kvm_s390_pv_unp args = {
         .addr = addr,
@@ -180,7 +192,8 @@ int s390_pv_unpack(uint64_t addr, uint64_t size, uint64_t tweak)
         .tweak = tweak,
     };
 
-    return s390_pv_cmd(KVM_PV_UNPACK, &args);
+    *pv_cmd = KVM_PV_UNPACK;
+    return s390_pv_cmd_pvrc_pvrrc(*pv_cmd, &args, pv_rc, pv_rrc);
 }
 
 void s390_pv_prep_reset(void)
@@ -188,9 +201,10 @@ void s390_pv_prep_reset(void)
     s390_pv_cmd_exit(KVM_PV_PREP_RESET, NULL);
 }
 
-int s390_pv_verify(void)
+int s390_pv_verify(uint16_t *pv_cmd, uint16_t *pv_rc, uint16_t *pv_rrc)
 {
-    return s390_pv_cmd(KVM_PV_VERIFY, NULL);
+    *pv_cmd = KVM_PV_VERIFY;
+    return s390_pv_cmd_pvrc_pvrrc(*pv_cmd, NULL, pv_rc, pv_rrc);
 }
 
 void s390_pv_unshare(void)
@@ -198,13 +212,13 @@ void s390_pv_unshare(void)
     s390_pv_cmd_exit(KVM_PV_UNSHARE_ALL, NULL);
 }
 
-void s390_pv_inject_reset_error(CPUState *cs)
+void s390_pv_inject_reset_error(CPUState *cs, uint64_t *resp)
 {
     int r1 = (cs->kvm_run->s390_sieic.ipa & 0x00f0) >> 4;
     CPUS390XState *env = &S390_CPU(cs)->env;
 
     /* Report that we are unable to enter protected mode */
-    env->regs[r1 + 1] = DIAG_308_RC_INVAL_FOR_PV;
+    env->regs[r1 + 1] = *resp;
 }
 
 uint64_t kvm_s390_pv_dmp_get_size_cpu(void)
diff --git a/target/s390x/kvm/pv.h b/target/s390x/kvm/pv.h
index 5e9c8bd351..7c003d1e28 100644
--- a/target/s390x/kvm/pv.h
+++ b/target/s390x/kvm/pv.h
@@ -42,12 +42,16 @@ int s390_pv_query_info(void);
 int s390_pv_vm_enable(void);
 void s390_pv_vm_disable(void);
 bool s390_pv_vm_try_disable_async(S390CcwMachineState *ms);
-int s390_pv_set_sec_parms(uint64_t origin, uint64_t length, Error **errp);
-int s390_pv_unpack(uint64_t addr, uint64_t size, uint64_t tweak);
+int s390_pv_set_sec_parms(uint64_t origin, uint64_t length,
+                          Error **errp, uint16_t *pv_cmd,
+                          uint16_t *pv_rc, uint16_t *pv_rrc);
+int s390_pv_unpack(uint64_t addr, uint64_t size,
+                   uint64_t tweak, uint16_t *pv_cmd,
+                   uint16_t *pv_rc, uint16_t *pv_rrc);
 void s390_pv_prep_reset(void);
-int s390_pv_verify(void);
+int s390_pv_verify(uint16_t *pv_cmd, uint16_t *pv_rc, uint16_t *pv_rrc);
 void s390_pv_unshare(void);
-void s390_pv_inject_reset_error(CPUState *cs);
+void s390_pv_inject_reset_error(CPUState *cs, uint64_t *resp);
 uint64_t kvm_s390_pv_dmp_get_size_cpu(void);
 uint64_t kvm_s390_pv_dmp_get_size_mem_state(void);
 uint64_t kvm_s390_pv_dmp_get_size_completion_data(void);
@@ -63,12 +67,19 @@ static inline int s390_pv_vm_enable(void) { return 0; }
 static inline void s390_pv_vm_disable(void) {}
 static inline bool s390_pv_vm_try_disable_async(S390CcwMachineState *ms) { return false; }
 static inline int s390_pv_set_sec_parms(uint64_t origin, uint64_t length,
-                                        Error **errp) { return 0; }
-static inline int s390_pv_unpack(uint64_t addr, uint64_t size, uint64_t tweak) { return 0; }
+                                        Error **errp, uint16_t *pv_cmd,
+                                        uint16_t *pv_rc, uint16_t *pv_rrc)
+                                        { return 0; }
+static inline int s390_pv_unpack(uint64_t addr, uint64_t size,
+                                 uint64_t tweak, uint16_t *pv_cmd,
+                                 uint16_t *pv_rc, uint16_t *pv_rrc)
+                                 { return 0; }
 static inline void s390_pv_prep_reset(void) {}
-static inline int s390_pv_verify(void) { return 0; }
+static inline int s390_pv_verify(uint16_t *pv_cmd,
+                                 uint16_t *pv_rc,
+                                 uint16_t *pv_rrc) { return 0; }
 static inline void s390_pv_unshare(void) {}
-static inline void s390_pv_inject_reset_error(CPUState *cs) {};
+static inline void s390_pv_inject_reset_error(CPUState *cs, uint64_t *resp) {};
 static inline uint64_t kvm_s390_pv_dmp_get_size_cpu(void) { return 0; }
 static inline uint64_t kvm_s390_pv_dmp_get_size_mem_state(void) { return 0; }
 static inline uint64_t kvm_s390_pv_dmp_get_size_completion_data(void) { return 0; }
-- 
2.49.0

Re: [PATCH v1 1/3] target/s390x: Introduce constant when checking if PV header couldn't be decrypted

[Steffen Eiden]

On Fri, Apr 11, 2025 at 11:22:31AM +0200, Gautam Gala wrote:
> Introduce a named constant when checking the Set Secure Configuration parameters
> UV call return code for the case where no valid host key was found and therefore
> the PV header couldn't be decrypted (0x108).
> 
> Signed-off-by: Gautam Gala <ggala@linux.ibm.com>

Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>

Re: [PATCH v1 2/3] target/s390x: introduce function when exiting PV

[Steffen Eiden]

On Fri, Apr 11, 2025 at 11:22:32AM +0200, Gautam Gala wrote:
> introduce a static function when exiting PV. The function replaces an
> existing macro (s390_pv_cmd_exit).
> 
> Signed-off-by: Gautam Gala <ggala@linux.ibm.com>
> ---
>  target/s390x/kvm/pv.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/target/s390x/kvm/pv.c b/target/s390x/kvm/pv.c
> index 3a0a971f0b..b4abda2cef 100644
> --- a/target/s390x/kvm/pv.c
> +++ b/target/s390x/kvm/pv.c
> @@ -59,14 +59,15 @@ static int __s390_pv_cmd(uint32_t cmd, const char *cmdname, void *data,
>   */
>  #define s390_pv_cmd(cmd, data) __s390_pv_cmd(cmd, #cmd, data, NULL)
>  #define s390_pv_cmd_pvrc(cmd, data, pvrc) __s390_pv_cmd(cmd, #cmd, data, pvrc)
> -#define s390_pv_cmd_exit(cmd, data)    \
> -{                                      \
> -    int rc;                            \
> -                                       \
> -    rc = __s390_pv_cmd(cmd, #cmd, data, NULL); \
> -    if (rc) {                          \
> -        exit(1);                       \
> -    }                                  \
> +
> +static void s390_pv_cmd_exit(uint32_t cmd, void *data)
> +{
> +    int rc;
> +
> +    rc = s390_pv_cmd(cmd, data);
> +    if (rc) {

I am not sure if that violates Qemu coding style but you could inline the rc
variable here to reduce LoC.

> +        exit(1);
> +    }
>  }
>  
>  int s390_pv_query_info(void)
> -- 
> 2.49.0
> 
> 

Re: [PATCH v1 3/3] target/s390x: Return UVC cmd code, RC and RRC value when DIAG 308 Subcode 10 fails to enter secure mode

[Steffen Eiden]

On Fri, Apr 11, 2025 at 11:22:33AM +0200, Gautam Gala wrote:
> Extend DIAG308 subcode 10 to return the UVC RC, RRC and command code
> in bit positions 32-47, 16-31, and 0-15 of register R1 + 1 if the
> function does not complete successfully (in addition to the
> previously returned diag response code in bit position 47-63).
> 
> Signed-off-by: Gautam Gala <ggala@linux.ibm.com>
> ---
>  hw/s390x/ipl.c             | 11 ++++++----
>  hw/s390x/ipl.h             |  5 +++--
>  hw/s390x/s390-virtio-ccw.c | 24 +++++++++++++++------
>  target/s390x/kvm/pv.c      | 44 +++++++++++++++++++++++++-------------
>  target/s390x/kvm/pv.h      | 27 ++++++++++++++++-------
>  5 files changed, 76 insertions(+), 35 deletions(-)
> 
> diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
> index ce6f6078d7..4f3e3945f1 100644
> --- a/hw/s390x/ipl.c
> +++ b/hw/s390x/ipl.c
> @@ -676,7 +676,8 @@ static void s390_ipl_prepare_qipl(S390CPU *cpu)
>      cpu_physical_memory_unmap(addr, len, 1, len);
>  }
>  
> -int s390_ipl_prepare_pv_header(Error **errp)
> +int s390_ipl_prepare_pv_header(Error **errp, uint16_t *pv_cmd,
> +                               uint16_t *pv_rc, uint16_t *pv_rrc)

`Error **errp` should be the last argument. (multiple locations)

...
  
> +struct diag308response {
> +    uint16_t pv_cmd;
> +    uint16_t pv_rrc;
> +    uint16_t pv_rc;
> +    uint16_t diag_rc;
> +};
> +

I think Qemu style wants you to use CamelCase here.
See e.g `390CcwMachineState` below


>  static S390CPU *s390x_new_cpu(const char *typename, uint32_t core_id,
>                                Error **errp)
>  {
> @@ -364,7 +371,10 @@ static void s390_machine_unprotect(S390CcwMachineState *ms)
>      ram_block_discard_disable(false);
>  }
>  

...

> @@ -452,6 +462,7 @@ static void s390_machine_reset(MachineState *machine, ResetType type)
>  {
>      S390CcwMachineState *ms = S390_CCW_MACHINE(machine);
>      enum s390_reset reset_type;
> +    struct diag308response resp;

Reverse Christmas tree.

>      CPUState *cs, *t;
>      S390CPU *cpu;
>  

...