| Message ID | 1442591670-5216-3-git-send-email-rkrcmar@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Sep 18, 2015 at 05:54:30PM +0200, Radim Kr?má? 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 Kr?má? <rkrcmar@redhat.com> > --- > 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 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 22/09/2015 21:01, Marcelo Tosatti wrote: > On Fri, Sep 18, 2015 at 05:54:30PM +0200, Radim Kr?má? 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 Kr?má? <rkrcmar@redhat.com> >> --- >> 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 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Sep 22, 2015 at 09:52:49PM +0200, Paolo Bonzini wrote: > > > On 22/09/2015 21:01, Marcelo Tosatti wrote: > > On Fri, Sep 18, 2015 at 05:54:30PM +0200, Radim Kr?má? 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 Kr?má? <rkrcmar@redhat.com> > >> --- > >> 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 The patch is correct. Overflow (issue raised) is only an issue without PVCLOCK_TSC_STABLE_BIT. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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;
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 Kr?má? <rkrcmar@redhat.com> --- arch/x86/include/asm/pvclock-abi.h | 1 + arch/x86/kvm/x86.c | 4 ---- 2 files changed, 1 insertion(+), 4 deletions(-)