| Message ID | 20200204175913.74901-1-avagin@gmail.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | arm64: add the time namespace support | expand |
Vincenzo, could you take a look this patchset? On Tue, Feb 04, 2020 at 09:59:08AM -0800, Andrei Vagin wrote: > Allocate the time namespace page among VVAR pages and add the logic > to handle faults on VVAR properly. > > If a task belongs to a time namespace then the VVAR page which contains > the system wide VDSO data is replaced with a namespace specific page > which has the same layout as the VVAR page. That page has vdso_data->seq > set to 1 to enforce the slow path and vdso_data->clock_mode set to > VCLOCK_TIMENS to enforce the time namespace handling path. > > The extra check in the case that vdso_data->seq is odd, e.g. a concurrent > update of the VDSO data is in progress, is not really affecting regular > tasks which are not part of a time namespace as the task is spin waiting > for the update to finish and vdso_data->seq to become even again. > > If a time namespace task hits that code path, it invokes the corresponding > time getter function which retrieves the real VVAR page, reads host time > and then adds the offset for the requested clock which is stored in the > special VVAR page. > > Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Dmitry Safonov <dima@arista.com> > > Andrei Vagin (5): > arm64/vdso: use the fault callback to map vvar pages > arm64/vdso: Zap vvar pages when switching to a time namespace > arm64/vdso: Add time napespace page > arm64/vdso: Handle faults on timens page > arm64/vdso: Restrict splitting VVAR VMA > > arch/arm64/Kconfig | 1 + > .../include/asm/vdso/compat_gettimeofday.h | 11 ++ > arch/arm64/include/asm/vdso/gettimeofday.h | 8 ++ > arch/arm64/kernel/vdso.c | 134 ++++++++++++++++-- > arch/arm64/kernel/vdso/vdso.lds.S | 3 +- > arch/arm64/kernel/vdso32/vdso.lds.S | 3 +- > include/vdso/datapage.h | 1 + > 7 files changed, 147 insertions(+), 14 deletions(-) > > -- > 2.24.1 >
Hi Andrei, On 17/02/2020 15:34, Andrei Vagin wrote: > Vincenzo, could you take a look this patchset? > Apologize for not getting to this yet. I will have a look at your patches during this week. > On Tue, Feb 04, 2020 at 09:59:08AM -0800, Andrei Vagin wrote: >> Allocate the time namespace page among VVAR pages and add the logic >> to handle faults on VVAR properly. >> >> If a task belongs to a time namespace then the VVAR page which contains >> the system wide VDSO data is replaced with a namespace specific page >> which has the same layout as the VVAR page. That page has vdso_data->seq >> set to 1 to enforce the slow path and vdso_data->clock_mode set to >> VCLOCK_TIMENS to enforce the time namespace handling path. >> >> The extra check in the case that vdso_data->seq is odd, e.g. a concurrent >> update of the VDSO data is in progress, is not really affecting regular >> tasks which are not part of a time namespace as the task is spin waiting >> for the update to finish and vdso_data->seq to become even again. >> >> If a time namespace task hits that code path, it invokes the corresponding >> time getter function which retrieves the real VVAR page, reads host time >> and then adds the offset for the requested clock which is stored in the >> special VVAR page. >> >> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> >> Cc: Thomas Gleixner <tglx@linutronix.de> >> Cc: Dmitry Safonov <dima@arista.com> >> >> Andrei Vagin (5): >> arm64/vdso: use the fault callback to map vvar pages >> arm64/vdso: Zap vvar pages when switching to a time namespace >> arm64/vdso: Add time napespace page >> arm64/vdso: Handle faults on timens page >> arm64/vdso: Restrict splitting VVAR VMA >> >> arch/arm64/Kconfig | 1 + >> .../include/asm/vdso/compat_gettimeofday.h | 11 ++ >> arch/arm64/include/asm/vdso/gettimeofday.h | 8 ++ >> arch/arm64/kernel/vdso.c | 134 ++++++++++++++++-- >> arch/arm64/kernel/vdso/vdso.lds.S | 3 +- >> arch/arm64/kernel/vdso32/vdso.lds.S | 3 +- >> include/vdso/datapage.h | 1 + >> 7 files changed, 147 insertions(+), 14 deletions(-) >> >> -- >> 2.24.1 >>
Hi Andrei, On 04/02/2020 17:59, Andrei Vagin wrote: > Allocate the time namespace page among VVAR pages and add the logic > to handle faults on VVAR properly. > > If a task belongs to a time namespace then the VVAR page which contains > the system wide VDSO data is replaced with a namespace specific page > which has the same layout as the VVAR page. That page has vdso_data->seq > set to 1 to enforce the slow path and vdso_data->clock_mode set to > VCLOCK_TIMENS to enforce the time namespace handling path. > > The extra check in the case that vdso_data->seq is odd, e.g. a concurrent > update of the VDSO data is in progress, is not really affecting regular > tasks which are not part of a time namespace as the task is spin waiting > for the update to finish and vdso_data->seq to become even again. > > If a time namespace task hits that code path, it invokes the corresponding > time getter function which retrieves the real VVAR page, reads host time > and then adds the offset for the requested clock which is stored in the > special VVAR page. > Thank you for adding the arm64 support of time namespaces. Overall it looks fine to me even if I have few comments. I will test it in the coming days just to make sure I did not miss something major. I will keep you updated on the results. > Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Dmitry Safonov <dima@arista.com> > > Andrei Vagin (5): > arm64/vdso: use the fault callback to map vvar pages > arm64/vdso: Zap vvar pages when switching to a time namespace > arm64/vdso: Add time napespace page > arm64/vdso: Handle faults on timens page > arm64/vdso: Restrict splitting VVAR VMA > > arch/arm64/Kconfig | 1 + > .../include/asm/vdso/compat_gettimeofday.h | 11 ++ > arch/arm64/include/asm/vdso/gettimeofday.h | 8 ++ > arch/arm64/kernel/vdso.c | 134 ++++++++++++++++-- > arch/arm64/kernel/vdso/vdso.lds.S | 3 +- > arch/arm64/kernel/vdso32/vdso.lds.S | 3 +- > include/vdso/datapage.h | 1 + > 7 files changed, 147 insertions(+), 14 deletions(-) >
On Thu, Feb 20, 2020 at 12:40:47PM +0000, Vincenzo Frascino wrote: > Hi Andrei, > > On 04/02/2020 17:59, Andrei Vagin wrote: > > Allocate the time namespace page among VVAR pages and add the logic > > to handle faults on VVAR properly. > > > > If a task belongs to a time namespace then the VVAR page which contains > > the system wide VDSO data is replaced with a namespace specific page > > which has the same layout as the VVAR page. That page has vdso_data->seq > > set to 1 to enforce the slow path and vdso_data->clock_mode set to > > VCLOCK_TIMENS to enforce the time namespace handling path. > > > > The extra check in the case that vdso_data->seq is odd, e.g. a concurrent > > update of the VDSO data is in progress, is not really affecting regular > > tasks which are not part of a time namespace as the task is spin waiting > > for the update to finish and vdso_data->seq to become even again. > > > > If a time namespace task hits that code path, it invokes the corresponding > > time getter function which retrieves the real VVAR page, reads host time > > and then adds the offset for the requested clock which is stored in the > > special VVAR page. > > > > Thank you for adding the arm64 support of time namespaces. Overall it looks fine > to me even if I have few comments. I will test it in the coming days just to > make sure I did not miss something major. I will keep you updated on the results. Thank you for the review. All comments look reasonable and I will address them and post a second version. Thanks, Andrei