Linux as a guest on KVM hypervisor, the only user of the pvclock
vsyscall interface, does not require notification on task migration
because:

1. cpu ID number maps 1:1 to per-CPU pvclock time info.
2. per-CPU pvclock time info is updated if the
   underlying CPU changes.
3. that version is increased whenever underlying CPU
   changes.

Which is sufficient to guarantee nanoseconds counter
is calculated properly.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NGleb Natapov <gleb@redhat.com>

Originally from Jeremy Fitzhardinge.

Introduce generic, non hypervisor specific, pvclock initialization
routines.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

As noted by Gleb, not advertising SSE2 support implies
no RDTSC barriers.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Acked-by: NGlauber Costa <glommer@parallels.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Originally from Jeremy Fitzhardinge.

So code can be reused.
Acked-by: NGlauber Costa <glommer@parallels.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Commit de2d1a52 ("KVM: Fix register corruption in pvclock_scale_delta")
introduced a mul instruction that may have only a memory operand; the
assembler therefore cannot select the correct size:

   pvclock.s:229: Error: no instruction mnemonic suffix given and no register
operands; can't size instruction

In this example the assembler is:

         #APP
         mul -48(%rbp) ; shrd $32, %rdx, %rax
         #NO_APP

A simple solution is to use mulq.
Signed-off-by: NDuncan Sands <baldrick@free.fr>
Signed-off-by: NAvi Kivity <avi@redhat.com>

The 128-bit multiply in pvclock.h was missing an output constraint for
EDX which caused a register corruption to appear.  Thanks to Ulrich for
diagnosing the EDX corruption and Avi for providing this fix.
Signed-off-by: NZachary Amsden <zamsden@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

If the guest domain has been suspend/resumed or migrated, then the
system clock backing the pvclock clocksource may revert to a smaller
value (ie, can be non-monotonic across the migration/save-restore).

Make sure we zero last_value in that case so that the domain
continues to see clock updates.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The scale_delta function for shift / multiply with 31-bit
precision moves to a common header so it can be used by both
kernel and kvm module.
Signed-off-by: NZachary Amsden <zamsden@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

This patch removes one padding byte and transform it into a flags
field. New versions of guests using pvclock will query these flags
upon each read.

Flags, however, will only be interpreted when the guest decides to.
It uses the pvclock_valid_flags function to signal that a specific
set of flags should be taken into consideration. Which flags are valid
are usually devised via HV negotiation.
Signed-off-by: NGlauber Costa <glommer@redhat.com>
CC: Jeremy Fitzhardinge <jeremy@goop.org>
Acked-by: NZachary Amsden <zamsden@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Change header guards named "ASM_X86__*" to "_ASM_X86_*" since:

a. the double underscore is ugly and pointless.
b. no leading underscore violates namespace constraints.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

KVM intends to use paravirt code to calibrate khz. Xen
current code will do just fine. So as a first step, factor out
code to pvclock.c.
Signed-off-by: NGlauber Costa <gcosta@redhat.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

This patch is the result of an automatic script that consolidates the
format of all the headers in include/asm-x86/.

The format:

1. No leading underscore. Names with leading underscores are reserved.
2. Pathname components are separated by two underscores. So we can
   distinguish between mm_types.h and mm/types.h.
3. Everything except letters and numbers are turned into single
   underscores.
Signed-off-by: NVegard Nossum <vegard.nossum@gmail.com>

This patch adds structs for the paravirt clocksource ABI
used by both xen and kvm (pvclock-abi.h).

It also adds some helper functions to read system time and
wall clock time from a paravirtual clocksource (pvclock.[ch]).
They are based on the xen code.  They are enabled using
CONFIG_PARAVIRT_CLOCK.

Subsequent patches of this series will put the code in use.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Acked-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>