lwn.git/arch/x86/kernel/cpu/mshyperv.c, branch standardize-docs

x86/hyperv: Read TSC frequency from a synthetic MSR

2017-06-22T13:35:12+00:00

It was found that SMI_TRESHOLD of 50000 is not enough for Hyper-V guests in nested environment and falling back to counting jiffies is not an option for Gen2 guests as they don't have PIT. As Hyper-V provides TSC frequency in a synthetic MSR we can just use this information instead of doing a error prone calibration. Reported-and-tested-by: Ladi Prosek Signed-off-by: Vitaly Kuznetsov Signed-off-by: Thomas Gleixner Cc: Stephen Hemminger Cc: Haiyang Zhang Cc: Jork Loeser Cc: devel@linuxdriverproject.org Cc: "K. Y. Srinivasan" Link: http://lkml.kernel.org/r/20170622100730.18112-3-vkuznets@redhat.com

x86/hyperv: Check frequency MSRs presence according to the specification

2017-06-22T13:35:11+00:00

Hyper-V TLFS specifies two bits which should be checked before accessing frequency MSRs: - AccessFrequencyMsrs (BIT(11) in EAX) which indicates if we have access to frequency MSRs. - FrequencyMsrsAvailable (BIT(8) in EDX) which indicates is these MSRs are present. Rename and specify these bits accordingly. Signed-off-by: Vitaly Kuznetsov Signed-off-by: Thomas Gleixner Cc: Stephen Hemminger Cc: Haiyang Zhang Cc: Ladi Prosek Cc: Jork Loeser Cc: devel@linuxdriverproject.org Cc: "K. Y. Srinivasan" Link: http://lkml.kernel.org/r/20170622100730.18112-2-vkuznets@redhat.com

Drivers: hv: Issue explicit EOI when autoeoi is not enabled

2017-04-08T16:07:51+00:00

When auto EOI is not enabled; issue an explicit EOI for hyper-v interrupts. Fixes: 6c248aad81c8 ("Drivers: hv: Base autoeoi enablement based on hypervisor hints") Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: Move the extracting of Hypervisor version information

2017-01-20T13:48:03+00:00

As part of the effort to separate out architecture specific code, extract hypervisor version information in an architecture specific file. Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: Consolidate all Hyper-V specific clocksource code

2017-01-20T13:48:03+00:00

As part of the effort to separate out architecture specific code, consolidate all Hyper-V specific clocksource code to an architecture specific code. Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman

Drivers: hv vmbus: Move Hypercall page setup out of common code

2017-01-19T10:42:07+00:00

As part of the effort to separate out architecture specific code, move the hypercall page setup to an architecture specific file. Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman

clocksource: Use a plain u64 instead of cycle_t

2016-12-25T10:04:12+00:00

There is no point in having an extra type for extra confusion. u64 is unambiguous. Conversion was done with the following coccinelle script: @rem@ @@ -typedef u64 cycle_t; @fix@ typedef cycle_t; @@ -cycle_t +u64 Signed-off-by: Thomas Gleixner Cc: Peter Zijlstra Cc: John Stultz

x86/hyperv: Handle unknown NMIs on one CPU when unknown_nmi_panic

2016-12-20T08:31:48+00:00

There is a feature in Hyper-V ('Debug-VM --InjectNonMaskableInterrupt') which injects NMI to the guest. We may want to crash the guest and do kdump on this NMI by enabling unknown_nmi_panic. To make kdump succeed we need to allow the kdump kernel to re-establish VMBus connection so it will see VMBus devices (storage, network,..). To properly unload VMBus making it possible to start over during kdump we need to do the following: - Send an 'unload' message to the hypervisor. This can be done on any CPU so we do this the crashing CPU. - Receive the 'unload finished' reply message. WS2012R2 delivers this message to the CPU which was used to establish VMBus connection during module load and this CPU may differ from the CPU sending 'unload'. Receiving a VMBus message means the following: - There is a per-CPU slot in memory for one message. This slot can in theory be accessed by any CPU. - We get an interrupt on the CPU when a message was placed into the slot. - When we read the message we need to clear the slot and signal the fact to the hypervisor. In case there are more messages to this CPU pending the hypervisor will deliver the next message. The signaling is done by writing to an MSR so this can only be done on the appropriate CPU. To avoid doing cross-CPU work on crash we have vmbus_wait_for_unload() function which checks message slots for all CPUs in a loop waiting for the 'unload finished' messages. However, there is an issue which arises when these conditions are met: - We're crashing on a CPU which is different from the one which was used to initially contact the hypervisor. - The CPU which was used for the initial contact is blocked with interrupts disabled and there is a message pending in the message slot. In this case we won't be able to read the 'unload finished' message on the crashing CPU. This is reproducible when we receive unknown NMIs on all CPUs simultaneously: the first CPU entering panic() will proceed to crash and all other CPUs will stop themselves with interrupts disabled. The suggested solution is to handle unknown NMIs for Hyper-V guests on the first CPU which gets them only. This will allow us to rely on VMBus interrupt handler being able to receive the 'unload finish' message in case it is delivered to a different CPU. The issue is not reproducible on WS2016 as Debug-VM delivers NMI to the boot CPU only, WS2012R2 and earlier Hyper-V versions are affected. Signed-off-by: Vitaly Kuznetsov Acked-by: K. Y. Srinivasan Cc: devel@linuxdriverproject.org Cc: Haiyang Zhang Link: http://lkml.kernel.org/r/20161202100720.28121-1-vkuznets@redhat.com Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar

x86: Remove empty idle.h header

2016-12-09T20:23:22+00:00

One include less is always a good thing(tm). Good riddance. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Cc: Jiri Olsa Link: http://lkml.kernel.org/r/20161209182912.2726-6-bp@alien8.de Signed-off-by: Thomas Gleixner

x86/kernel: Audit and remove any unnecessary uses of module.h

2016-07-14T13:06:41+00:00

Historically a lot of these existed because we did not have a distinction between what was modular code and what was providing support to modules via EXPORT_SYMBOL and friends. That changed when we forked out support for the latter into the export.h file. This means we should be able to reduce the usage of module.h in code that is obj-y Makefile or bool Kconfig. The advantage in doing so is that module.h itself sources about 15 other headers; adding significantly to what we feed cpp, and it can obscure what headers we are effectively using. Since module.h was the source for init.h (for __init) and for export.h (for EXPORT_SYMBOL) we consider each obj-y/bool instance for the presence of either and replace as needed. Build testing revealed some implicit header usage that was fixed up accordingly. Note that some bool/obj-y instances remain since module.h is the header for some exception table entry stuff, and for things like __init_or_module (code that is tossed when MODULES=n). Signed-off-by: Paul Gortmaker Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20160714001901.31603-4-paul.gortmaker@windriver.com Signed-off-by: Ingo Molnar