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[Qemu-devel] [PATCH 07/88] kvmclock: Ensure time in migration never goes
From: |
Michael Roth |
Subject: |
[Qemu-devel] [PATCH 07/88] kvmclock: Ensure time in migration never goes backward |
Date: |
Thu, 8 Jan 2015 11:33:11 -0600 |
From: Alexander Graf <address@hidden>
When we migrate we ask the kernel about its current belief on what the guest
time would be. However, I've seen cases where the kvmclock guest structure
indicates a time more recent than the kvm returned time.
To make sure we never go backwards, calculate what the guest would have seen as
time at the point of migration and use that value instead of the kernel
returned one when it's more recent.
This bases the view of the kvmclock after migration on the
same foundation in host as well as guest.
Signed-off-by: Alexander Graf <address@hidden>
Cc: address@hidden
Reviewed-by: Marcelo Tosatti <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
(cherry picked from commit 9a48bcd1b82494671c111109b0eefdb882581499)
Signed-off-by: Michael Roth <address@hidden>
---
hw/i386/kvm/clock.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 49 insertions(+)
diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
index 9d65766..1ac60d6 100644
--- a/hw/i386/kvm/clock.c
+++ b/hw/i386/kvm/clock.c
@@ -14,6 +14,7 @@
*/
#include "qemu-common.h"
+#include "qemu/host-utils.h"
#include "sysemu/sysemu.h"
#include "sysemu/kvm.h"
#include "sysemu/cpus.h"
@@ -35,6 +36,48 @@ typedef struct KVMClockState {
bool clock_valid;
} KVMClockState;
+struct pvclock_vcpu_time_info {
+ uint32_t version;
+ uint32_t pad0;
+ uint64_t tsc_timestamp;
+ uint64_t system_time;
+ uint32_t tsc_to_system_mul;
+ int8_t tsc_shift;
+ uint8_t flags;
+ uint8_t pad[2];
+} __attribute__((__packed__)); /* 32 bytes */
+
+static uint64_t kvmclock_current_nsec(KVMClockState *s)
+{
+ CPUState *cpu = first_cpu;
+ CPUX86State *env = cpu->env_ptr;
+ hwaddr kvmclock_struct_pa = env->system_time_msr & ~1ULL;
+ uint64_t migration_tsc = env->tsc;
+ struct pvclock_vcpu_time_info time;
+ uint64_t delta;
+ uint64_t nsec_lo;
+ uint64_t nsec_hi;
+ uint64_t nsec;
+
+ if (!(env->system_time_msr & 1ULL)) {
+ /* KVM clock not active */
+ return 0;
+ }
+
+ cpu_physical_memory_read(kvmclock_struct_pa, &time, sizeof(time));
+
+ assert(time.tsc_timestamp <= migration_tsc);
+ delta = migration_tsc - time.tsc_timestamp;
+ if (time.tsc_shift < 0) {
+ delta >>= -time.tsc_shift;
+ } else {
+ delta <<= time.tsc_shift;
+ }
+
+ mulu64(&nsec_lo, &nsec_hi, delta, time.tsc_to_system_mul);
+ nsec = (nsec_lo >> 32) | (nsec_hi << 32);
+ return nsec + time.system_time;
+}
static void kvmclock_vm_state_change(void *opaque, int running,
RunState state)
@@ -46,9 +89,15 @@ static void kvmclock_vm_state_change(void *opaque, int
running,
if (running) {
struct kvm_clock_data data;
+ uint64_t time_at_migration = kvmclock_current_nsec(s);
s->clock_valid = false;
+ /* We can't rely on the migrated clock value, just discard it */
+ if (time_at_migration) {
+ s->clock = time_at_migration;
+ }
+
data.clock = s->clock;
data.flags = 0;
ret = kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, &data);
--
1.9.1
- [Qemu-devel] Patch Round-up for stable 2.1.3, freeze on 2015-01-14, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 02/88] qdev: Add cleanup logic in device_set_realized() to avoid resource leak, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 04/88] xhci PCIe endpoint migration compatibility fix, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 01/88] qdev: Use NULL instead of local_err for qbus_child unrealize, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 03/88] exec: file_ram_alloc(): print error when prealloc fails, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 10/88] virtio-pci: enable bus master for old guests, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 05/88] Introduce cpu_clean_all_dirty, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 08/88] kvmclock: Add comment explaining why we need cpu_clean_all_dirty(), Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 09/88] pci: Use bus master address space for delivering MSI/MSI-X messages, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 07/88] kvmclock: Ensure time in migration never goes backward,
Michael Roth <=
- [Qemu-devel] [PATCH 06/88] kvmclock: Ensure proper env->tsc value for kvmclock_current_nsec calculation, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 12/88] hw/arm/virt: fix pl011 and pl031 irq flags, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 13/88] gdbstub: init mon_chr through qemu_chr_alloc, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 14/88] qapi: add visit_start_union and visit_end_union, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 11/88] spapr_pci: map the MSI window in each PHB, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 15/88] qapi: dealloc visitor, implement visit_start_union, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 16/88] tests: add QMP input visitor test for unions with no discriminator, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 17/88] qemu-iotests: Test missing "driver" key for blockdev-add, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 18/88] monitor: Reset HMP mon->rs in CHR_EVENT_OPEN, Michael Roth, 2015/01/08
- [Qemu-devel] [PATCH 20/88] vhost-user: fix VIRTIO_NET_F_MRG_RXBUF negotiation, Michael Roth, 2015/01/08