From: Pekka Enberg <penberg@kernel.org>
Date: Mon, 10 Jan 2011 19:46:37 +0000 (+0200)
Subject: kvm,8250: Fix "too much work for irq4" problems
X-Git-Tag: next-20110824~3^2~523
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=c7344091badfdb8fd3a23a4bfa2d22be8c84515e;p=karo-tx-linux.git

kvm,8250: Fix "too much work for irq4" problems

This patch fixes the "too much work for irq4" problems caused by the fact that
we never set the UART_IIR_NO_INT flag in the emulation layer. This makes the
interrupt handler in the guest kernel process as much as possible which
triggers a warning.

Signed-off-by: Pekka Enberg <penberg@kernel.org>
---

diff --git a/tools/kvm/8250-serial.c b/tools/kvm/8250-serial.c
index 6056ed6b30d0..834c523f4cff 100644
--- a/tools/kvm/8250-serial.c
+++ b/tools/kvm/8250-serial.c
@@ -23,6 +23,8 @@ struct serial8250_device {
 	uint8_t			mcr;
 	uint8_t			lsr;
 	uint8_t			scr;
+
+	uint8_t			counter;
 };
 
 static struct serial8250_device devices[] = {
@@ -37,11 +39,15 @@ static struct serial8250_device devices[] = {
 	[1]	= {
 		.iobase			= 0x2f8,
 		.irq			= 3,
+
+		.iir			= UART_IIR_NO_INT,
 	},
 	/* ttyS2 */
 	[2]	= {
 		.iobase			= 0x3e8,
 		.irq			= 4,
+
+		.iir			= UART_IIR_NO_INT,
 	},
 };
 
@@ -158,6 +164,11 @@ static bool serial8250_out(struct kvm *self, uint16_t port, void *data, int size
 			}
 			fflush(stdout);
 
+			if (dev->counter++ > 10) {
+				dev->iir		= UART_IIR_NO_INT;
+				dev->counter		= 0;
+			}
+
 			break;
 		}
 		case UART_IER:
@@ -200,6 +211,8 @@ static bool serial8250_in(struct kvm *self, uint16_t port, void *data, int size,
 	switch (offset) {
 	case UART_TX:
 		if (dev->lsr & UART_LSR_DR) {
+			dev->iir		= UART_IIR_NO_INT;
+
 			dev->lsr		&= ~UART_LSR_DR;
 			ioport__write8(data, dev->thr);
 		}