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[Qemu-devel] [PATCH 1/4] kvm: i8254: Cache kernel clock offset in KVMPIT
From: |
Marcelo Tosatti |
Subject: |
[Qemu-devel] [PATCH 1/4] kvm: i8254: Cache kernel clock offset in KVMPITState |
Date: |
Tue, 14 Aug 2012 20:59:46 -0300 |
From: Jan Kiszka <address@hidden>
To prepare the final fix for clock calibration issues with the in-kernel
PIT, we want to cache the offset between vmclock and the clock used by
the in-kernel PIT. So far, we only need to update it when the VM state
changes between running and stopped because we only read the in-kernel
PIT state while the VM is running.
Signed-off-by: Jan Kiszka <address@hidden>
Signed-off-by: Marcelo Tosatti <address@hidden>
---
hw/kvm/i8254.c | 38 ++++++++++++++++++++++++--------------
1 files changed, 24 insertions(+), 14 deletions(-)
diff --git a/hw/kvm/i8254.c b/hw/kvm/i8254.c
index c5d3711..c235d80 100644
--- a/hw/kvm/i8254.c
+++ b/hw/kvm/i8254.c
@@ -35,7 +35,8 @@
typedef struct KVMPITState {
PITCommonState pit;
LostTickPolicy lost_tick_policy;
- bool state_valid;
+ bool vm_stopped;
+ int64_t kernel_clock_offset;
} KVMPITState;
static int64_t abs64(int64_t v)
@@ -43,19 +44,11 @@ static int64_t abs64(int64_t v)
return v < 0 ? -v : v;
}
-static void kvm_pit_get(PITCommonState *pit)
+static void kvm_pit_update_clock_offset(KVMPITState *s)
{
- KVMPITState *s = DO_UPCAST(KVMPITState, pit, pit);
- struct kvm_pit_state2 kpit;
- struct kvm_pit_channel_state *kchan;
- struct PITChannelState *sc;
int64_t offset, clock_offset;
struct timespec ts;
- int i, ret;
-
- if (s->state_valid) {
- return;
- }
+ int i;
/*
* Measure the delta between CLOCK_MONOTONIC, the base used for
@@ -72,6 +65,21 @@ static void kvm_pit_get(PITCommonState *pit)
clock_offset = offset;
}
}
+ s->kernel_clock_offset = clock_offset;
+}
+
+static void kvm_pit_get(PITCommonState *pit)
+{
+ KVMPITState *s = DO_UPCAST(KVMPITState, pit, pit);
+ struct kvm_pit_state2 kpit;
+ struct kvm_pit_channel_state *kchan;
+ struct PITChannelState *sc;
+ int i, ret;
+
+ /* No need to re-read the state if VM is stopped. */
+ if (s->vm_stopped) {
+ return;
+ }
if (kvm_has_pit_state2()) {
ret = kvm_vm_ioctl(kvm_state, KVM_GET_PIT2, &kpit);
@@ -106,7 +114,7 @@ static void kvm_pit_get(PITCommonState *pit)
sc->mode = kchan->mode;
sc->bcd = kchan->bcd;
sc->gate = kchan->gate;
- sc->count_load_time = kchan->count_load_time + clock_offset;
+ sc->count_load_time = kchan->count_load_time + s->kernel_clock_offset;
}
sc = &pit->channels[0];
@@ -211,10 +219,12 @@ static void kvm_pit_vm_state_change(void *opaque, int
running,
KVMPITState *s = opaque;
if (running) {
- s->state_valid = false;
+ kvm_pit_update_clock_offset(s);
+ s->vm_stopped = false;
} else {
+ kvm_pit_update_clock_offset(s);
kvm_pit_get(&s->pit);
- s->state_valid = true;
+ s->vm_stopped = true;
}
}
--
1.7.6.4
- [Qemu-devel] [PATCH 0/4] [PULL] qemu-kvm.git uq/master queue, Marcelo Tosatti, 2012/08/14
- [Qemu-devel] [PATCH 2/4] kvm: i8254: Finish time conversion fix, Marcelo Tosatti, 2012/08/14
- [Qemu-devel] [PATCH 3/4] kvmvapic: Disable if there is insufficient memory, Marcelo Tosatti, 2012/08/14
- [Qemu-devel] [PATCH 1/4] kvm: i8254: Cache kernel clock offset in KVMPITState,
Marcelo Tosatti <=
- [Qemu-devel] [PATCH 4/4] update-linux-headers.sh: Pull in asm-generic/kvm_para.h, Marcelo Tosatti, 2012/08/14
- Re: [Qemu-devel] [PATCH 0/4] [PULL] qemu-kvm.git uq/master queue, Peter Maydell, 2012/08/15
- Re: [Qemu-devel] [PATCH 0/4] [PULL] qemu-kvm.git uq/master queue, Anthony Liguori, 2012/08/15