On Fri, Oct 13, 2017 at 10:45 PM, Boris Ostrovsky boris.ostrovsky@oracle.com wrote:
On 10/13/2017 02:37 PM, Arnd Bergmann wrote:
The x86 platform operations are fairly isolated, so we can change them from using timespec to timespec64. I checked that All the users and callers are safe, and there is only one critical function that is broken beyond 2106:
pvclock_read_wallclock() uses a 32-bit number of seconds since the epoch to communicate the boot time between host and guest in a virtual environment. This will work until 2106, but we should ideally find a replacement anyway. I've added a comment about it there.
Signed-off-by: Arnd Bergmann arnd@arndb.de
arch/x86/include/asm/intel_mid_vrtc.h | 4 ++-- arch/x86/include/asm/mc146818rtc.h | 4 ++-- arch/x86/include/asm/pvclock.h | 2 +- arch/x86/include/asm/x86_init.h | 6 +++--- arch/x86/kernel/kvmclock.c | 4 ++-- arch/x86/kernel/pvclock.c | 12 +++++++++--- arch/x86/kernel/rtc.c | 16 ++++++++-------- arch/x86/platform/intel-mid/intel_mid_vrtc.c | 10 +++++----- arch/x86/xen/time.c | 10 +++++----- 9 files changed, 37 insertions(+), 31 deletions(-)
Xen bits: Reviewed-by: Boris Ostrovsky boris.ostrovsky@oracle.com
Thanks!
Since you've looked at it overall, do you have an opinion on the question how to fix the PV interface to deal with the pvclock_wall_clock overflow?
Should we add a new version now and deprecate the existing one, or do you think that y2106 is far enough out that we should just ignore the problem?
with a couple of nits:
@@ -136,11 +136,17 @@ void pvclock_read_wallclock(struct pvclock_wall_clock *wall_clock, rmb(); /* fetch time before checking version */ } while ((wall_clock->version & 1) || (version != wall_clock->version));
/** Note: wall_clock->sec is a u32 value, so it can only store dates* between 1970 and 2106. To allow times beyond that, we need to* create a new hypercall interface with an extended pvclock_wall_clock* structure like ARM has.*/I think this comment block should be moved up above 'now.tv_sec = wall_clock->sec;'
right, changed.
delta = pvclock_clocksource_read(vcpu_time); /* time since system boot */ delta += now.tv_sec * (u64)NSEC_PER_SEC + now.tv_nsec;Now that tv_sec is a 64-bit quantity the cast can be dropped.
Ok dropped. In the meantime I had noticed two more problems with the patch that I did not see earlier when I tested with another patch applied as well. The kbuild test robot reported the exact same problems, and I've done a few hundred randconfig builds without the other patch now, so I'm fairly confident that there are no other problems like those.
I'll follow up with a v2 patch soon.
Arnd