linux-toradex.git/drivers/clocksource/hyperv_timer.c, branch v5.17-rc4

drivers: hv: Decouple Hyper-V clock/timer code from VMbus drivers

2021-07-19T09:24:28+00:00

Hyper-V clock/timer code in hyperv_timer.c is mostly independent from
other VMbus drivers, but building for ARM64 without hyperv_timer.c
shows some remaining entanglements.  A default implementation of
hv_read_reference_counter can just read a Hyper-V synthetic register
and be independent of hyperv_timer.c, so move this code out and into
hv_common.c. Then it can be used by the timesync driver even if
hyperv_timer.c isn't built on a particular architecture.  If
hyperv_timer.c *is* built, it can override with a faster implementation.

Also provide stubs for stimer functions called by the VMbus driver when
hyperv_timer.c isn't built.

No functional changes.

Signed-off-by: Michael Kelley 
Link: https://lore.kernel.org/r/1626220906-22629-1-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu

clocksource/drivers/hyper-v: Re-enable VDSO_CLOCKMODE_HVCLOCK on X86

2021-05-14T12:55:13+00:00

Mohammed reports (https://bugzilla.kernel.org/show_bug.cgi?id=213029)
the commit e4ab4658f1cf ("clocksource/drivers/hyper-v: Handle vDSO
differences inline") broke vDSO on x86. The problem appears to be that
VDSO_CLOCKMODE_HVCLOCK is an enum value in 'enum vdso_clock_mode' and
'#ifdef VDSO_CLOCKMODE_HVCLOCK' branch evaluates to false (it is not
a define).

Use a dedicated HAVE_VDSO_CLOCKMODE_HVCLOCK define instead.

Fixes: e4ab4658f1cf ("clocksource/drivers/hyper-v: Handle vDSO differences inline")
Reported-by: Mohammed Gamal 
Suggested-by: Thomas Gleixner 
Signed-off-by: Vitaly Kuznetsov 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Michael Kelley 
Link: https://lore.kernel.org/r/20210513073246.1715070-1-vkuznets@redhat.com

Merge tag 'hyperv-next-signed-20210426' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

2021-04-26T17:44:16+00:00

Pull Hyper-V updates from Wei Liu:

 - VMBus enhancement

 - Free page reporting support for Hyper-V balloon driver

 - Some patches for running Linux as Arm64 Hyper-V guest

 - A few misc clean-up patches

* tag 'hyperv-next-signed-20210426' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: (30 commits)
  drivers: hv: Create a consistent pattern for checking Hyper-V hypercall status
  x86/hyperv: Move hv_do_rep_hypercall to asm-generic
  video: hyperv_fb: Add ratelimit on error message
  Drivers: hv: vmbus: Increase wait time for VMbus unload
  Drivers: hv: vmbus: Initialize unload_event statically
  Drivers: hv: vmbus: Check for pending channel interrupts before taking a CPU offline
  Drivers: hv: vmbus: Drivers: hv: vmbus: Introduce CHANNELMSG_MODIFYCHANNEL_RESPONSE
  Drivers: hv: vmbus: Introduce and negotiate VMBus protocol version 5.3
  Drivers: hv: vmbus: Use after free in __vmbus_open()
  Drivers: hv: vmbus: remove unused function
  Drivers: hv: vmbus: Remove unused linux/version.h header
  x86/hyperv: remove unused linux/version.h header
  x86/Hyper-V: Support for free page reporting
  x86/hyperv: Fix unused variable 'hi' warning in hv_apic_read
  x86/hyperv: Fix unused variable 'msr_val' warning in hv_qlock_wait
  hv: hyperv.h: a few mundane typo fixes
  drivers: hv: Fix EXPORT_SYMBOL and tab spaces issue
  Drivers: hv: vmbus: Drop error message when 'No request id available'
  asm-generic/hyperv: Add missing function prototypes per -W1 warnings
  clocksource/drivers/hyper-v: Move handling of STIMER0 interrupts
  ...

timekeeping, clocksource: Fix various typos in comments

2021-03-22T22:06:48+00:00

Fix ~56 single-word typos in timekeeping & clocksource code comments.

Signed-off-by: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: John Stultz 
Cc: Stephen Boyd 
Cc: Daniel Lezcano 
Cc: linux-kernel@vger.kernel.org

clocksource/drivers/hyper-v: Move handling of STIMER0 interrupts

2021-03-08T17:33:00+00:00

STIMER0 interrupts are most naturally modeled as per-cpu IRQs. But
because x86/x64 doesn't have per-cpu IRQs, the core STIMER0 interrupt
handling machinery is done in code under arch/x86 and Linux IRQs are
not used. Adding support for ARM64 means adding equivalent code
using per-cpu IRQs under arch/arm64.

A better model is to treat per-cpu IRQs as the normal path (which it is
for modern architectures), and the x86/x64 path as the exception. Do this
by incorporating standard Linux per-cpu IRQ allocation into the main
SITMER0 driver code, and bypass it in the x86/x64 exception case. For
x86/x64, special case code is retained under arch/x86, but no STIMER0
interrupt handling code is needed under arch/arm64.

No functional change.

Signed-off-by: Michael Kelley 
Acked-by: Daniel Lezcano 
Link: https://lore.kernel.org/r/1614721102-2241-11-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu

clocksource/drivers/hyper-v: Set clocksource rating based on Hyper-V feature

2021-03-08T17:33:00+00:00

On x86/x64, the TSC clocksource is available in a Hyper-V VM only if
Hyper-V provides the TSC_INVARIANT flag. The rating on the Hyper-V
Reference TSC page clocksource is currently set so that it will not
override the TSC clocksource in this case.  Alternatively, if the TSC
clocksource is not available, then the Hyper-V clocksource is used.

But on ARM64, the Hyper-V Reference TSC page clocksource should
override the ARM arch counter, since the Hyper-V clocksource provides
scaling and offsetting during live migrations that is not provided
for the ARM arch counter.

To get the needed behavior for both x86/x64 and ARM64, tweak the
logic by defaulting the Hyper-V Reference TSC page clocksource
rating to a large value that will always override.  If the Hyper-V
TSC_INVARIANT flag is set, then reduce the rating so that it will not
override the TSC.

While the logic for getting there is slightly different, the net
result in the normal cases is no functional change.

Signed-off-by: Michael Kelley 
Acked-by: Daniel Lezcano 
Link: https://lore.kernel.org/r/1614721102-2241-10-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu

clocksource/drivers/hyper-v: Handle sched_clock differences inline

2021-03-08T17:33:00+00:00

While the Hyper-V Reference TSC code is architecture neutral, the
pv_ops.time.sched_clock() function is implemented for x86/x64, but not
for ARM64. Current code calls a utility function under arch/x86 (and
coming, under arch/arm64) to handle the difference.

Change this approach to handle the difference inline based on whether
GENERIC_SCHED_CLOCK is present.  The new approach removes code under
arch/* since the difference is tied more to the specifics of the Linux
implementation than to the architecture.

No functional change.

Signed-off-by: Michael Kelley 
Reviewed-by: Boqun Feng 
Acked-by: Daniel Lezcano 
Link: https://lore.kernel.org/r/1614721102-2241-9-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu

clocksource/drivers/hyper-v: Handle vDSO differences inline

2021-03-08T17:33:00+00:00

While the driver for the Hyper-V Reference TSC and STIMERs is architecture
neutral, vDSO is implemented for x86/x64, but not for ARM64.  Current code
calls into utility functions under arch/x86 (and coming, under arch/arm64)
to handle the difference.

Change this approach to handle the difference inline based on whether
VDSO_CLOCK_MODE_HVCLOCK is present.  The new approach removes code under
arch/* since the difference is tied more to the specifics of the Linux
implementation than to the architecture.

No functional change.

Signed-off-by: Michael Kelley 
Reviewed-by: Boqun Feng 
Acked-by: Daniel Lezcano 
Link: https://lore.kernel.org/r/1614721102-2241-8-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu

Drivers: hv: Redo Hyper-V synthetic MSR get/set functions

2021-03-08T17:32:59+00:00

Current code defines a separate get and set macro for each Hyper-V
synthetic MSR used by the VMbus driver. Furthermore, the get macro
can't be converted to a standard function because the second argument
is modified in place, which is somewhat bad form.

Redo this by providing a single get and a single set function that
take a parameter specifying the MSR to be operated on. Fixup usage
of the get function. Calling locations are no more complex than before,
but the code under arch/x86 and the upcoming code under arch/arm64
is significantly simplified.

Also standardize the names of Hyper-V synthetic MSRs that are
architecture neutral. But keep the old x86-specific names as aliases
that can be removed later when all references (particularly in KVM
code) have been cleaned up in a separate patch series.

No functional change.

Signed-off-by: Michael Kelley 
Reviewed-by: Boqun Feng 
Link: https://lore.kernel.org/r/1614721102-2241-4-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu

clocksource/hyperv: use MSR-based access if running as root

2021-02-11T08:47:06+00:00

When Linux runs as the root partition, the setup required for TSC page
is different. Luckily Linux also has access to the MSR based
clocksource. We can just disable the TSC page clocksource if Linux is
the root partition.

Signed-off-by: Wei Liu 
Acked-by: Daniel Lezcano 
Reviewed-by: Pavel Tatashin 
Reviewed-by: Michael Kelley 
Link: https://lore.kernel.org/r/20210203150435.27941-5-wei.liu@kernel.org