| Message ID | 1458231136-13457-2-git-send-email-joao.m.martins@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 17/03/16 16:12, Joao Martins wrote: > This field has two possible flags (as of latest pvclock ABI > shared with KVM). > > flags: bits in this field indicate extended capabilities > coordinated between the guest and the hypervisor. Specifically > on KVM, availability of specific flags has to be checked in > 0x40000001 cpuid leaf. On Xen, we don't have that but we can > still check some of the flags after registering the time info > page since a force_update_vcpu_system_time is performed. > > Current flags are: > > flag bit | cpuid bit | meaning > ------------------------------------------------------------- > | | time measures taken across > 0 | 24 | multiple cpus are guaranteed to > | | be monotonic > ------------------------------------------------------------- > | | guest vcpu has been paused by > 1 | N/A | the host > | | > ------------------------------------------------------------- > > Signed-off-by: Joao Martins <joao.m.martins@oracle.com> > Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com> Has the Linux maintainers file been patched to include xen-devel, to avoid them altering our ABI unnoticed in the future?
On 03/18/2016 08:12 PM, Andrew Cooper wrote: > On 17/03/16 16:12, Joao Martins wrote: >> This field has two possible flags (as of latest pvclock ABI >> shared with KVM). >> >> flags: bits in this field indicate extended capabilities >> coordinated between the guest and the hypervisor. Specifically >> on KVM, availability of specific flags has to be checked in >> 0x40000001 cpuid leaf. On Xen, we don't have that but we can >> still check some of the flags after registering the time info >> page since a force_update_vcpu_system_time is performed. >> >> Current flags are: >> >> flag bit | cpuid bit | meaning >> ------------------------------------------------------------- >> | | time measures taken across >> 0 | 24 | multiple cpus are guaranteed to >> | | be monotonic >> ------------------------------------------------------------- >> | | guest vcpu has been paused by >> 1 | N/A | the host >> | | >> ------------------------------------------------------------- >> >> Signed-off-by: Joao Martins <joao.m.martins@oracle.com> >> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > > Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com> > Thanks! > Has the Linux maintainers file been patched to include xen-devel, to > avoid them altering our ABI unnoticed in the future? > Not yet, but I had planned to do so when sending the v2 of the linux side. But perhaps you want it beforehand?
On 21/03/16 11:42, Joao Martins wrote: > > On 03/18/2016 08:12 PM, Andrew Cooper wrote: >> On 17/03/16 16:12, Joao Martins wrote: >>> This field has two possible flags (as of latest pvclock ABI >>> shared with KVM). >>> >>> flags: bits in this field indicate extended capabilities >>> coordinated between the guest and the hypervisor. Specifically >>> on KVM, availability of specific flags has to be checked in >>> 0x40000001 cpuid leaf. On Xen, we don't have that but we can >>> still check some of the flags after registering the time info >>> page since a force_update_vcpu_system_time is performed. >>> >>> Current flags are: >>> >>> flag bit | cpuid bit | meaning >>> ------------------------------------------------------------- >>> | | time measures taken across >>> 0 | 24 | multiple cpus are guaranteed to >>> | | be monotonic >>> ------------------------------------------------------------- >>> | | guest vcpu has been paused by >>> 1 | N/A | the host >>> | | >>> ------------------------------------------------------------- >>> >>> Signed-off-by: Joao Martins <joao.m.martins@oracle.com> >>> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> >> Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com> >> > Thanks! > >> Has the Linux maintainers file been patched to include xen-devel, to >> avoid them altering our ABI unnoticed in the future? >> > Not yet, but I had planned to do so when sending the v2 of the linux side. But > perhaps you want it beforehand? Just so long as it doesn't get lost. ~Andrew
On 03/21/2016 11:43 AM, Andrew Cooper wrote: > On 21/03/16 11:42, Joao Martins wrote: >> >> On 03/18/2016 08:12 PM, Andrew Cooper wrote: >>> On 17/03/16 16:12, Joao Martins wrote: >>>> This field has two possible flags (as of latest pvclock ABI >>>> shared with KVM). >>>> >>>> flags: bits in this field indicate extended capabilities >>>> coordinated between the guest and the hypervisor. Specifically >>>> on KVM, availability of specific flags has to be checked in >>>> 0x40000001 cpuid leaf. On Xen, we don't have that but we can >>>> still check some of the flags after registering the time info >>>> page since a force_update_vcpu_system_time is performed. >>>> >>>> Current flags are: >>>> >>>> flag bit | cpuid bit | meaning >>>> ------------------------------------------------------------- >>>> | | time measures taken across >>>> 0 | 24 | multiple cpus are guaranteed to >>>> | | be monotonic >>>> ------------------------------------------------------------- >>>> | | guest vcpu has been paused by >>>> 1 | N/A | the host >>>> | | >>>> ------------------------------------------------------------- >>>> >>>> Signed-off-by: Joao Martins <joao.m.martins@oracle.com> >>>> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> >>> Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com> >>> >> Thanks! >> >>> Has the Linux maintainers file been patched to include xen-devel, to >>> avoid them altering our ABI unnoticed in the future? >>> >> Not yet, but I had planned to do so when sending the v2 of the linux side. But >> perhaps you want it beforehand? > > Just so long as it doesn't get lost. It definitely won't get lost. Joao
>>> On 17.03.16 at 17:12, <joao.m.martins@oracle.com> wrote: > --- a/xen/include/public/xen.h > +++ b/xen/include/public/xen.h > @@ -614,10 +614,14 @@ struct vcpu_time_info { > */ > uint32_t tsc_to_system_mul; > int8_t tsc_shift; > - int8_t pad1[3]; > + int8_t flags; For use as flags I'm sure this would better be uint8_t. Jan
On 21/03/16 15:10, Jan Beulich wrote: >>>> On 17.03.16 at 17:12, <joao.m.martins@oracle.com> wrote: >> --- a/xen/include/public/xen.h >> +++ b/xen/include/public/xen.h >> @@ -614,10 +614,14 @@ struct vcpu_time_info { >> */ >> uint32_t tsc_to_system_mul; >> int8_t tsc_shift; >> - int8_t pad1[3]; >> + int8_t flags; > For use as flags I'm sure this would better be uint8_t. Sadly not possible. Linux have already made the above adjustment without (CC'ing xen-devel), so that ABI is set. ~Andrew
On 03/21/2016 03:27 PM, Andrew Cooper wrote: > On 21/03/16 15:10, Jan Beulich wrote: >>>>> On 17.03.16 at 17:12, <joao.m.martins@oracle.com> wrote: >>> --- a/xen/include/public/xen.h >>> +++ b/xen/include/public/xen.h >>> @@ -614,10 +614,14 @@ struct vcpu_time_info { >>> */ >>> uint32_t tsc_to_system_mul; >>> int8_t tsc_shift; >>> - int8_t pad1[3]; >>> + int8_t flags; >> For use as flags I'm sure this would better be uint8_t. > > Sadly not possible. Linux have already made the above adjustment > without (CC'ing xen-devel), so that ABI is set. > I was double checking again and it's my mistake. Both flags and pad fields are uint8_t. I will fix both in v2, to make sure it's all kept the same on both header files. My apologies. Joao
diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h index 64ba7ab..08373f6 100644 --- a/xen/include/public/xen.h +++ b/xen/include/public/xen.h @@ -614,10 +614,14 @@ struct vcpu_time_info { */ uint32_t tsc_to_system_mul; int8_t tsc_shift; - int8_t pad1[3]; + int8_t flags; + int8_t pad1[2]; }; /* 32 bytes */ typedef struct vcpu_time_info vcpu_time_info_t; +#define PVCLOCK_TSC_STABLE_BIT (1 << 0) +#define PVCLOCK_GUEST_STOPPED (1 << 1) + struct vcpu_info { /* * 'evtchn_upcall_pending' is written non-zero by Xen to indicate
This field has two possible flags (as of latest pvclock ABI shared with KVM). flags: bits in this field indicate extended capabilities coordinated between the guest and the hypervisor. Specifically on KVM, availability of specific flags has to be checked in 0x40000001 cpuid leaf. On Xen, we don't have that but we can still check some of the flags after registering the time info page since a force_update_vcpu_system_time is performed. Current flags are: flag bit | cpuid bit | meaning ------------------------------------------------------------- | | time measures taken across 0 | 24 | multiple cpus are guaranteed to | | be monotonic ------------------------------------------------------------- | | guest vcpu has been paused by 1 | N/A | the host | | ------------------------------------------------------------- Signed-off-by: Joao Martins <joao.m.martins@oracle.com> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> --- Cc: Ian Jackson <ian.jackson@eu.citrix.com> Cc: Jan Beulich <jbeulich@suse.com> Cc: Keir Fraser <keir@xen.org> Cc: Tim Deegan <tim@xen.org> --- xen/include/public/xen.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)