powerpc/xics: Harden xics hypervisor backend

During kdump stress testing I sometimes see the kdump kernel panic
with:

  Interrupt 0x306 (real) is invalid, disabling it.
  Kernel panic - not syncing: bad return code EOI - rc = -4, value=ff000306

Instead of panicing print the error message, dump the stack the first
time it happens and continue on. Add some more information to the
debug messages as well.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 27 insertions, 11 deletions

diff --git a/arch/powerpc/sysdev/xics/icp-hv.c b/arch/powerpc/sysdev/xics/icp-hv.c
index 9518d367a64f..784b3fc6f071 100644
--- a/arch/powerpc/sysdev/xics/icp-hv.c
+++ b/arch/powerpc/sysdev/xics/icp-hv.c
@@ -27,33 +27,49 @@ static inline unsigned int icp_hv_get_xirr(unsigned char cppr)
 {
         unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
         long rc;
+        unsigned int ret = XICS_IRQ_SPURIOUS;
 
         rc = plpar_hcall(H_XIRR, retbuf, cppr);
-        if (rc != H_SUCCESS)
-                panic(" bad return code xirr - rc = %lx\n", rc);
-        return (unsigned int)retbuf[0];
+        if (rc == H_SUCCESS) {
+                ret = (unsigned int)retbuf[0];
+        } else {
+                pr_err("%s: bad return code xirr cppr=0x%x returned %ld\n",
+                        __func__, cppr, rc);
+                WARN_ON_ONCE(1);
+        }
+
+        return ret;
 }
 
 static inline void icp_hv_set_xirr(unsigned int value)
 {
         long rc = plpar_hcall_norets(H_EOI, value);
-        if (rc != H_SUCCESS)
-                panic("bad return code EOI - rc = %ld, value=%x\n", rc, value);
+        if (rc != H_SUCCESS) {
+                pr_err("%s: bad return code eoi xirr=0x%x returned %ld\n",
+                        __func__, value, rc);
+                WARN_ON_ONCE(1);
+        }
 }
 
 static inline void icp_hv_set_cppr(u8 value)
 {
         long rc = plpar_hcall_norets(H_CPPR, value);
-        if (rc != H_SUCCESS)
-                panic("bad return code cppr - rc = %lx\n", rc);
+        if (rc != H_SUCCESS) {
+                pr_err("%s: bad return code cppr cppr=0x%x returned %ld\n",
+                        __func__, value, rc);
+                WARN_ON_ONCE(1);
+        }
 }
 
 static inline void icp_hv_set_qirr(int n_cpu , u8 value)
 {
-        long rc = plpar_hcall_norets(H_IPI, get_hard_smp_processor_id(n_cpu),
-                                     value);
-        if (rc != H_SUCCESS)
-                panic("bad return code qirr - rc = %lx\n", rc);
+        int hw_cpu = get_hard_smp_processor_id(n_cpu);
+        long rc = plpar_hcall_norets(H_IPI, hw_cpu, value);
+        if (rc != H_SUCCESS) {
+                pr_err("%s: bad return code qirr cpu=%d hw_cpu=%d mfrr=0x%x "
+                        "returned %ld\n", __func__, n_cpu, hw_cpu, value, rc);
+                WARN_ON_ONCE(1);
+        }
 }
 
 static void icp_hv_eoi(struct irq_data *d)