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Drivers: hv: vmbus: Implement Direct Mode for stimer0

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The 2016 version of Hyper-V offers the option to operate the guest VM
per-vcpu stimer's in Direct Mode, which means the timer interupts on its
own vector rather than queueing a VMbus message. Direct Mode reduces
timer processing overhead in both the hypervisor and the guest, and
avoids having timer interrupts pollute the VMbus interrupt stream for
the synthetic NIC and storage.  This patch enables Direct Mode by
default on stimer0 when running on a version of Hyper-V that supports
it.

In prep for coming support of Hyper-V on ARM64, the arch independent
portion of the code contains calls to routines that will be populated
on ARM64 but are not needed and do nothing on x86.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michael Kelley
2018-03-04 22:17:18 -07:00
committed by Greg Kroah-Hartman
parent ce767047b1
commit 248e742a39
10 changed files with 131 additions and 5 deletions
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3
arch/x86/include/uapi/asm/hyperv.h
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@@ -77,6 +77,9 @@
/* Crash MSR available */
#define HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE (1 << 10)
/* stimer Direct Mode is available */
#define HV_X64_STIMER_DIRECT_MODE_AVAILABLE (1 << 19)
/*
* Feature identification: EBX indicates which flags were specified at
* partition creation. The format is the same as the partition creation