[PATCH v3 7/8] tpm: Guard irq related ops in case interrupts are disabled

[Stefan Berger <stefanb@linux.vnet.ibm.com>]

Check for irq_num having the value of TPM_IRQ_DISABLED before calling any
IRQ related functions or allowing the user to try to enable interrupts.
Explicitly allow the value of TPM_IRQ_DISABLED in irq_num.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
 hw/tpm/tpm_tis_common.c | 12 +++++++++++-
 hw/tpm/tpm_tis_isa.c    |  6 ++++--
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/hw/tpm/tpm_tis_common.c b/hw/tpm/tpm_tis_common.c
index 0f42696f1f..13b233309e 100644
--- a/hw/tpm/tpm_tis_common.c
+++ b/hw/tpm/tpm_tis_common.c
@@ -359,7 +359,11 @@ static uint64_t tpm_tis_mmio_read(void *opaque, hwaddr addr,
         val = s->loc[locty].inte;
         break;
     case TPM_TIS_REG_INT_VECTOR:
-        val = s->irq_num;
+        if (s->irq_num != TPM_IRQ_DISABLED) {
+            val = s->irq_num;
+        } else {
+            val = 0;
+        }
         break;
     case TPM_TIS_REG_INT_STATUS:
         val = s->loc[locty].ints;
@@ -591,6 +595,9 @@ static void tpm_tis_mmio_write(void *opaque, hwaddr addr,
         if (s->active_locty != locty) {
             break;
         }
+        if (s->irq_num == TPM_IRQ_DISABLED) {
+            val &= ~TPM_TIS_INT_ENABLED;
+        }
 
         s->loc[locty].inte &= mask;
         s->loc[locty].inte |= (val & (TPM_TIS_INT_ENABLED |
@@ -601,6 +608,9 @@ static void tpm_tis_mmio_write(void *opaque, hwaddr addr,
         /* hard wired -- ignore */
         break;
     case TPM_TIS_REG_INT_STATUS:
+        if (s->irq_num == TPM_IRQ_DISABLED) {
+            break;
+        }
         /* clearing of interrupt flags */
         if (((val & TPM_TIS_INTERRUPTS_SUPPORTED)) &&
             (s->loc[locty].ints & TPM_TIS_INTERRUPTS_SUPPORTED)) {
diff --git a/hw/tpm/tpm_tis_isa.c b/hw/tpm/tpm_tis_isa.c
index 27222a9a49..d72f733ead 100644
--- a/hw/tpm/tpm_tis_isa.c
+++ b/hw/tpm/tpm_tis_isa.c
@@ -127,13 +127,15 @@ static void tpm_tis_isa_realizefn(DeviceState *dev, Error **errp)
         error_setg(errp, "'tpmdev' property is required");
         return;
     }
-    if (s->irq_num > 15) {
+    if (s->irq_num > 15 && s->irq_num != TPM_IRQ_DISABLED) {
         error_setg(errp, "IRQ %d is outside valid range of 0 to 15",
                    s->irq_num);
         return;
     }
 
-    isa_init_irq(ISA_DEVICE(dev), &s->irq, s->irq_num);
+    if (s->irq_num != TPM_IRQ_DISABLED) {
+        isa_init_irq(ISA_DEVICE(dev), &s->irq, s->irq_num);
+    }
 
     memory_region_add_subregion(isa_address_space(ISA_DEVICE(dev)),
                                 TPM_TIS_ADDR_BASE, &s->mmio);
-- 
2.24.1