From 5918245d224a7a527052ed30af2627187777a282 Mon Sep 17 00:00:00 2001
From: Richard Jones <rjones@redhat.com>
Date: Wed, 1 Nov 2017 11:33:01 +0100
Subject: [PATCH 6/7] i6300esb: fix timer overflow
RH-Author: Richard Jones <rjones@redhat.com>
Message-id: <1509535982-27927-3-git-send-email-rjones@redhat.com>
Patchwork-id: 77460
O-Subject: [RHEL-7.5 qemu-kvm PATCH v3 2/3] i6300esb: fix timer overflow
Bugzilla: 1470244
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Acked-by: Thomas Huth <thuth@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
From: Laurent Vivier <lvivier@redhat.com>
We use muldiv64() to compute the time to wait:
timeout = muldiv64(get_ticks_per_sec(), timeout, 33000000);
but get_ticks_per_sec() is 10^9 (30 bit value) and timeout
is a 35 bit value.
Whereas muldiv64 is:
uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c)
So we loose 3 bits of timeout.
Swapping get_ticks_per_sec() and timeout fixes it.
We can also replace it by a multiplication by 30 ns,
but this changes PCI clock frequency from 33MHz to 33.333333MHz
and we need to do this on all the QEMU PCI devices (later...)
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(cherry picked from commit fee562e9e41290a22623de83b673a8929ec5280d)
BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1470244
Upstream-status: fee562e9e41290a22623de83b673a8929ec5280d
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
hw/watchdog/wdt_i6300esb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/watchdog/wdt_i6300esb.c b/hw/watchdog/wdt_i6300esb.c
index be35034..fa8e3b9 100644
--- a/hw/watchdog/wdt_i6300esb.c
+++ b/hw/watchdog/wdt_i6300esb.c
@@ -132,7 +132,7 @@ static void i6300esb_restart_timer(I6300State *d, int stage)
* multiply here can exceed 64-bits, before we divide by 33MHz, so
* we use a higher-precision intermediate result.
*/
- timeout = muldiv64(get_ticks_per_sec(), timeout, 33000000);
+ timeout = muldiv64(timeout, get_ticks_per_sec(), 33000000);
i6300esb_debug("stage %d, timeout %" PRIi64 "\n", d->stage, timeout);
--
1.8.3.1