Some versions of Windows hang on reboot if their TSC value is greater
than 2^54. The calibration of the Hyper-V reference time overflows
and fails; as a result the processors' clock sources are out of sync.
As a workaround, reset the TSC to a small value. Do not do this
unconditionally and require a special property to be set.
Reported-by: Vadim Rozenfeld <vroze...@redhat.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
target/i386/cpu.c | 10 ++++++++++
target/i386/cpu.h | 3 +++
2 files changed, 13 insertions(+)
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index ec3b50bf6e..9b29cea8c4 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -5931,6 +5931,15 @@ static void x86_cpu_reset(DeviceState *dev)
env->xstate_bv = 0;
env->pat = 0x0007040600070406ULL;
+
+ /*
+ * Some versions of Windows hang on reboot if their TSC value is greater
+ * than 2^54. As a workaround, reset the TSC to a small value. Do not use
+ * zero, KVM applies special heuristics for CPU startup when TSC is
cleared.
+ */
+ if (cpu->tsc_clear_on_reset) {
+ env->tsc = 1;
+ }
env->msr_ia32_misc_enable = MSR_IA32_MISC_ENABLE_DEFAULT;
if (env->features[FEAT_1_ECX] & CPUID_EXT_MONITOR) {
env->msr_ia32_misc_enable |= MSR_IA32_MISC_ENABLE_MWAIT;
@@ -6957,6 +6966,7 @@ static Property x86_cpu_properties[] = {
false),
DEFINE_PROP_BOOL("vmware-cpuid-freq", X86CPU, vmware_cpuid_freq, true),
DEFINE_PROP_BOOL("tcg-cpuid", X86CPU, expose_tcg, true),
+ DEFINE_PROP_BOOL("tsc-clear-on-reset", X86CPU, tsc_clear_on_reset, true),
DEFINE_PROP_BOOL("x-migrate-smi-count", X86CPU, migrate_smi_count,
true),
/*
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index e31e6bd8b8..66f7901729 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1864,6 +1864,9 @@ struct ArchCPU {
/* Forcefully disable KVM PV features not exposed in guest CPUIDs */
bool kvm_pv_enforce_cpuid;
+ /* Clear TSC on reset */
+ bool tsc_clear_on_reset;
+
/* Number of physical address bits supported */
uint32_t phys_bits;
--
2.35.1
