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target/i386: properly reset TSC on reset

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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.

The issue is that the TSC _should_ be reset to 0 on CPU reset and
QEMU tries to do that.  However, KVM special cases writing 0 to the
TSC and thinks that QEMU is trying to hot-plug a CPU, which is
correct the first time through but not later.  Thwart this valiant
effort and reset the TSC to 1 instead, but only if the CPU has been
run once.

For this to work, env->tsc has to be moved to the part of CPUArchState
that is not zeroed at the beginning of x86_cpu_reset.

Reported-by: Vadim Rozenfeld <vrozenfe@redhat.com>
Supersedes: <20220324082346.72180-1-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini
2022-03-24 09:21:41 +01:00
parent de65b39a51
commit 5286c36622
2 changed files with 14 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
target/i386/cpu.c
View File

@@ -5931,6 +5931,19 @@ static void x86_cpu_reset(DeviceState *dev)
env->xstate_bv = 0;
env->pat = 0x0007040600070406ULL;
if (kvm_enabled()) {
/*
* KVM handles TSC = 0 specially and thinks we are hot-plugging
* a new CPU, use 1 instead to force a reset.
*/
if (env->tsc != 0) {
env->tsc = 1;
}
} else {
env->tsc = 0;
}
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;

2
target/i386/cpu.h
View File

@@ -1554,7 +1554,6 @@ typedef struct CPUArchState {
target_ulong kernelgsbase;
#endif
uint64_t tsc;
uint64_t tsc_adjust;
uint64_t tsc_deadline;
uint64_t tsc_aux;
@@ -1708,6 +1707,7 @@ typedef struct CPUArchState {
int64_t tsc_khz;
int64_t user_tsc_khz; /* for sanity check only */
uint64_t apic_bus_freq;
uint64_t tsc;
#if defined(CONFIG_KVM) || defined(CONFIG_HVF)
void *xsave_buf;
uint32_t xsave_buf_len;