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3da02409af
As reported in the community forum [0][1], QEMU processes for Linux
guests would consume more CPU on the host after an update to QEMU 9.2.
The issue was reproduced and bisecting pointed to QEMU commit
f0ccf77078 ("hpet: fix and cleanup persistence of interrupt status").
Some quick experimentation suggests that in particular the last part
is responsible for the issue:
> - the timer must be kept running even if not enabled, in
> order to set the ISR flag, so writes to HPET_TN_CFG must
> not call hpet_del_timer()
Users confirmed that setting the hpet=off machine flag works around
the issue[0]. For Windows (7 or later) guests, the flag is already
disabled, because of issues in the past [2].
Upstream suggested reverting the relevant patches for now [3], because
other issues were reported too. All except commit 5895879aca ("hpet:
remove unnecessary variable "index"") are actually dependent on each
other for cleanly reverting f0ccf77078, and while not strictly
required, that one was reverted too for completeness.
[0]: https://forum.proxmox.com/threads/163694/
[1]: https://forum.proxmox.com/threads/161849/post-756793
[2]: https://lists.proxmox.com/pipermail/pve-devel/2012-December/004958.html
[3]: https://lore.kernel.org/qemu-devel/CABgObfaKJ5NFVKmYLFmu4C0iZZLJJtcWksLCzyA0tBoz0koZ4A@mail.gmail.com/
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
69 lines
2.0 KiB
Diff
69 lines
2.0 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Fiona Ebner <f.ebner@proxmox.com>
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Date: Wed, 19 Mar 2025 17:31:11 +0100
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Subject: [PATCH] Revert "hpet: remove unnecessary variable "index""
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This reverts commit 5895879aca252f4ebb2d1078eaf836c61ec54e9b.
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Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
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---
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hw/timer/hpet.c | 15 ++++++++-------
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1 file changed, 8 insertions(+), 7 deletions(-)
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diff --git a/hw/timer/hpet.c b/hw/timer/hpet.c
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index b12bbaf10d..6f83d88516 100644
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--- a/hw/timer/hpet.c
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+++ b/hw/timer/hpet.c
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@@ -437,12 +437,12 @@ static uint64_t hpet_ram_read(void *opaque, hwaddr addr,
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unsigned size)
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{
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HPETState *s = opaque;
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- uint64_t cur_tick;
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+ uint64_t cur_tick, index;
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trace_hpet_ram_read(addr);
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-
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+ index = addr;
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/*address range of all TN regs*/
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- if (addr >= 0x100 && addr <= 0x3ff) {
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+ if (index >= 0x100 && index <= 0x3ff) {
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uint8_t timer_id = (addr - 0x100) / 0x20;
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HPETTimer *timer = &s->timer[timer_id];
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@@ -469,7 +469,7 @@ static uint64_t hpet_ram_read(void *opaque, hwaddr addr,
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break;
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}
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} else {
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- switch (addr) {
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+ switch (index) {
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case HPET_ID:
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return s->capability;
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case HPET_PERIOD:
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@@ -510,14 +510,15 @@ static void hpet_ram_write(void *opaque, hwaddr addr,
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{
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int i;
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HPETState *s = opaque;
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- uint64_t old_val, new_val, val;
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+ uint64_t old_val, new_val, val, index;
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trace_hpet_ram_write(addr, value);
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+ index = addr;
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old_val = hpet_ram_read(opaque, addr, 4);
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new_val = value;
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/*address range of all TN regs*/
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- if (addr >= 0x100 && addr <= 0x3ff) {
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+ if (index >= 0x100 && index <= 0x3ff) {
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uint8_t timer_id = (addr - 0x100) / 0x20;
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HPETTimer *timer = &s->timer[timer_id];
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@@ -619,7 +620,7 @@ static void hpet_ram_write(void *opaque, hwaddr addr,
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}
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return;
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} else {
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- switch (addr) {
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+ switch (index) {
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case HPET_ID:
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return;
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case HPET_CFG:
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