[PATCH v2 32/35] x86/hvm: add debugging facility to NS8250 UART emulator

[Denis Mukhin via B4 Relay <devnull+dmukhin.ford.com@xxxxxxxxxx>]

From: Denis Mukhin <dmukhin@xxxxxxxx>

Enable keyhandler mechanism for dumping state of emulated NS8250 on the
console.

Signed-off-by: Denis Mukhin <dmukhin@xxxxxxxx>
---
 xen/arch/x86/hvm/vuart_ns8250.c | 122 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)

diff --git a/xen/arch/x86/hvm/vuart_ns8250.c b/xen/arch/x86/hvm/vuart_ns8250.c
index 
779dbd80d7be4e070ea9df3ae736ecdc662a527a..c8c75afaf2b2419d1dae999da1d1e400fd367791
 100644
--- a/xen/arch/x86/hvm/vuart_ns8250.c
+++ b/xen/arch/x86/hvm/vuart_ns8250.c
@@ -25,6 +25,7 @@
 
 /* Development debugging */
 #define NS8250_LOG_LEVEL    0
+#undef NS8250_DEBUG
 
 #include <xen/types.h>
 #include <xen/event.h>
@@ -35,6 +36,9 @@
 #include <xen/resource.h>
 #include <xen/ctype.h>
 #include <xen/param.h>
+#if defined(NS8250_DEBUG)
+#include <xen/keyhandler.h>
+#endif
 #include <xen/console.h> /* console_input_domid() */
 #include <asm/setup.h>   /* max_init_domid */
 #include <asm/iocap.h>
@@ -625,6 +629,121 @@ static const char *ns8250_regname(
     return reg_names[reg][dir];
 }
 
+#if defined(NS8250_DEBUG)
+static void ns8250_dump(struct vuart_ns8250 *vdev)
+{
+    struct xencons_interface *cons = vdev->cons;
+    uint8_t val;
+
+    printk("I/O port %02"PRIx64" IRQ %d flags %"PRIx32" owner %d\n",
+            vdev->io_addr, vdev->irq,
+            vdev->flags, vdev->owner->domain_id);
+
+    printk("RX size %ld in_prod %d in_cons %d used %d\n",
+            sizeof(cons->in),
+            cons->in_prod, cons->in_cons,
+            cons->in_prod - cons->in_cons);
+
+    printk("TX size %ld out_prod %d out_cons %d used %d\n",
+            sizeof(cons->out),
+            cons->out_prod, cons->out_cons,
+            cons->out_prod - cons->out_cons);
+
+    printk("%02x RBR [ %c ] THR [ %c ] DLL %02x DLM %02x\n",
+            UART_RBR,
+            cons->in[MASK_XENCONS_IDX(cons->in_prod, cons)],
+            cons->out[MASK_XENCONS_IDX(cons->out_prod, cons)],
+            vdev->dl & 0xFFU, vdev->dl >> 8);
+
+    printk("%02"PRIx8" IER %02"PRIx8"\n", UART_IER, vdev->regs[UART_IER]);
+
+    val = (vdev->regs[UART_FCR] & UART_FCR_ENABLE) ? UART_IIR_FE_MASK : 0;
+    val |= ns8250_irq_reason(vdev);
+    printk("%02"PRIx8" FCR %02"PRIx8" IIR %02"PRIx8"\n",
+            UART_FCR, vdev->regs[UART_FCR], val);
+
+    printk("%02"PRIx8" LCR %02"PRIx8"\n", UART_LCR, vdev->regs[UART_LCR]);
+    printk("%02"PRIx8" MCR %02"PRIx8"\n", UART_MCR, vdev->regs[UART_MCR]);
+    printk("%02"PRIx8" LSR %02"PRIx8"\n", UART_LSR, vdev->regs[UART_LSR]);
+    printk("%02"PRIx8" MSR %02"PRIx8"\n", UART_MSR, vdev->regs[UART_MSR]);
+}
+
+static struct domain *rcu_find_first_domain_with_vuart(void)
+{
+    struct domain *d = NULL;
+    domid_t i;
+
+    for ( i = 0; i < max_init_domid + 1; i++ )
+    {
+        d = rcu_lock_domain_by_id(i);
+        if ( d == NULL )
+            continue;
+
+        if ( domain_has_vuart(d) )
+            break;
+
+        rcu_unlock_domain(d);
+    }
+
+    return d;
+}
+
+static void cf_check ns8250_keyhandler_show(unsigned char key)
+{
+    struct vuart_ns8250 *vdev;
+    struct domain *d;
+
+    d = rcu_find_first_domain_with_vuart();
+    if ( d == NULL )
+        return;
+
+    printk("'%c' pressed -> dumping virtual NS8250 state (d%d)\n",
+            key, d->domain_id);
+
+    vdev = &d->arch.hvm.vuart;
+    spin_lock(&vdev->lock);
+    ns8250_dump(vdev);
+    spin_unlock(&vdev->lock);
+
+    rcu_unlock_domain(d);
+}
+
+static void cf_check ns8250_keyhandler_irq(unsigned char key)
+{
+    struct vuart_ns8250 *vdev;
+    struct domain *d;
+
+    d = rcu_find_first_domain_with_vuart();
+    if ( d == NULL )
+        return;
+
+    printk("'%c' pressed -> triggering IRQ on virtual NS8250 (d%d)\n",
+            key, d->domain_id);
+
+    vdev = &d->arch.hvm.vuart;
+    spin_lock(&vdev->lock);
+    ns8250_irq_assert(vdev);
+    spin_unlock(&vdev->lock);
+
+    rcu_unlock_domain(d);
+}
+
+static void ns8250_keyhandler_init(void)
+{
+    register_keyhandler('1', ns8250_keyhandler_show,
+                        "dump virtual NS8250 state", 0);
+    register_keyhandler('2', ns8250_keyhandler_irq,
+                        "trigger IRQ from virtual NS8250", 0);
+}
+#else
+static inline void ns8250_keyhandler_init(void)
+{
+}
+static inline void ns8250_dump(struct vuart_ns8250 *vdev)
+{
+}
+#endif /* #if defined(NS8250_DEBUG) */
+
 /*
  * Emulate I/O access to NS8250 register.
  */
@@ -688,6 +807,7 @@ static int cf_check ns8250_io_handle(
     rc = X86EMUL_OKAY;
 
 out:
+    ns8250_dump(vdev);
     spin_unlock(&vdev->lock);
 
     return rc;
@@ -786,6 +906,7 @@ static int ns8250_init(struct domain *d, const struct 
resource *r)
     }
 
     spin_lock_init(&vdev->lock);
+    ns8250_keyhandler_init();
     hvm_irq_lower(d, vdev->irq);
 
     vdev->dl = (UART_CLOCK_HZ / 115200) >> 4; /* Report 115200 baud rate */
@@ -852,6 +973,7 @@ int vuart_putchar(struct vuart_ns8250 *vdev, char ch)
     ns8250_irq_assert(vdev);
 
 out:
+    ns8250_dump(vdev);
     spin_unlock(&vdev->lock);
 
     return rc;

-- 
2.34.1