On 22/09/2015 21:01, Marcelo Tosatti wrote:
> On Fri, Sep 18, 2015 at 05:54:30PM +0200, Radim Krčmář wrote:
>> Shifting pvclock_vcpu_time_info.system_time on write to KVM system time
>> MSR is a change of ABI. Probably only 2.6.16 based SLES 10 breaks due
>> to its custom enhancements to kvmclock, but KVM never declared the MSR
>> only for one-shot initialization. (Doc says that only one write is
>> needed.)
>>
>> This reverts commit b7e60c5aedd2b63f16ef06fde4f81ca032211bc5.
>> And adds a note to the definition of PVCLOCK_COUNTS_FROM_ZERO.
>>
>> Signed-off-by: Radim Krčmář <rkrcmar@xxxxxxxxxx>
>> ---
>> arch/x86/include/asm/pvclock-abi.h | 1 +
>> arch/x86/kvm/x86.c | 4 ----
>> 2 files changed, 1 insertion(+), 4 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/pvclock-abi.h b/arch/x86/include/asm/pvclock-abi.h
>> index 655e07a48f6c..67f08230103a 100644
>> --- a/arch/x86/include/asm/pvclock-abi.h
>> +++ b/arch/x86/include/asm/pvclock-abi.h
>> @@ -41,6 +41,7 @@ struct pvclock_wall_clock {
>>
>> #define PVCLOCK_TSC_STABLE_BIT (1 << 0)
>> #define PVCLOCK_GUEST_STOPPED (1 << 1)
>> +/* PVCLOCK_COUNTS_FROM_ZERO broke ABI and can't be used anymore. */
>> #define PVCLOCK_COUNTS_FROM_ZERO (1 << 2)
>> #endif /* __ASSEMBLY__ */
>> #endif /* _ASM_X86_PVCLOCK_ABI_H */
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 18d59b584dee..34d33f4757d2 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -1707,8 +1707,6 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
>> vcpu->pvclock_set_guest_stopped_request = false;
>> }
>>
>> - pvclock_flags |= PVCLOCK_COUNTS_FROM_ZERO;
>> -
>> /* If the host uses TSC clocksource, then it is stable */
>> if (use_master_clock)
>> pvclock_flags |= PVCLOCK_TSC_STABLE_BIT;
>> @@ -2006,8 +2004,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>> &vcpu->requests);
>>
>> ka->boot_vcpu_runs_old_kvmclock = tmp;
>> -
>> - ka->kvmclock_offset = -get_kernel_ns();
>> }
>>
>> vcpu->arch.time = data;
>> --
>> 2.5.2
>
> ACK
So I suppose you changed your mind :) but can you explain the reasoning?
Paolo
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