Commit e1449007 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'x86-hyperv-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 hyperv updates from Ingo Molnar:
 "Avoid boot time TSC calibration on Hyper-V hosts, to improve
  calibration robustness. (Vitaly Kuznetsov)"

* 'x86-hyperv-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/hyperv: Read TSC frequency from a synthetic MSR
  x86/hyperv: Check frequency MSRs presence according to the specification
parents e6529f6f 71c2a2d0
......@@ -34,16 +34,10 @@
#define HV_X64_MSR_REFERENCE_TSC 0x40000021
/*
* There is a single feature flag that signifies the presence of the MSR
* that can be used to retrieve both the local APIC Timer frequency as
* well as the TSC frequency.
* There is a single feature flag that signifies if the partition has access
* to MSRs with local APIC and TSC frequencies.
*/
/* Local APIC timer frequency MSR (HV_X64_MSR_APIC_FREQUENCY) is available */
#define HV_X64_MSR_APIC_FREQUENCY_AVAILABLE (1 << 11)
/* TSC frequency MSR (HV_X64_MSR_TSC_FREQUENCY) is available */
#define HV_X64_MSR_TSC_FREQUENCY_AVAILABLE (1 << 11)
#define HV_X64_ACCESS_FREQUENCY_MSRS (1 << 11)
/*
* Basic SynIC MSRs (HV_X64_MSR_SCONTROL through HV_X64_MSR_EOM
......@@ -73,6 +67,9 @@
*/
#define HV_X64_MSR_STAT_PAGES_AVAILABLE (1 << 8)
/* Frequency MSRs available */
#define HV_FEATURE_FREQUENCY_MSRS_AVAILABLE (1 << 8)
/* Crash MSR available */
#define HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE (1 << 10)
......
......@@ -161,6 +161,15 @@ static int hv_nmi_unknown(unsigned int val, struct pt_regs *regs)
}
#endif
static unsigned long hv_get_tsc_khz(void)
{
unsigned long freq;
rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
return freq / 1000;
}
static void __init ms_hyperv_init_platform(void)
{
int hv_host_info_eax;
......@@ -193,8 +202,15 @@ static void __init ms_hyperv_init_platform(void)
hv_host_info_edx >> 24, hv_host_info_edx & 0xFFFFFF);
}
if (ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&
ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
x86_platform.calibrate_tsc = hv_get_tsc_khz;
x86_platform.calibrate_cpu = hv_get_tsc_khz;
}
#ifdef CONFIG_X86_LOCAL_APIC
if (ms_hyperv.features & HV_X64_MSR_APIC_FREQUENCY_AVAILABLE) {
if (ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&
ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
/*
* Get the APIC frequency.
*/
......
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