diff options
Diffstat (limited to 'arch/x86/hyperv/hv_init.c')
| -rw-r--r-- | arch/x86/hyperv/hv_init.c | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index b5c8e04deacb..860233af4568 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -24,6 +24,79 @@ #include <linux/version.h> #include <linux/vmalloc.h> #include <linux/mm.h> +#include <linux/clockchips.h> + + +#ifdef CONFIG_X86_64 + +static struct ms_hyperv_tsc_page *tsc_pg; + +static u64 read_hv_clock_tsc(struct clocksource *arg) +{ + u64 current_tick; + + if (tsc_pg->tsc_sequence != 0) { + /* + * Use the tsc page to compute the value. + */ + + while (1) { + u64 tmp; + u32 sequence = tsc_pg->tsc_sequence; + u64 cur_tsc; + u64 scale = tsc_pg->tsc_scale; + s64 offset = tsc_pg->tsc_offset; + + rdtscll(cur_tsc); + /* current_tick = ((cur_tsc *scale) >> 64) + offset */ + asm("mulq %3" + : "=d" (current_tick), "=a" (tmp) + : "a" (cur_tsc), "r" (scale)); + + current_tick += offset; + if (tsc_pg->tsc_sequence == sequence) + return current_tick; + + if (tsc_pg->tsc_sequence != 0) + continue; + /* + * Fallback using MSR method. + */ + break; + } + } + rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick); + return current_tick; +} + +static struct clocksource hyperv_cs_tsc = { + .name = "hyperv_clocksource_tsc_page", + .rating = 400, + .read = read_hv_clock_tsc, + .mask = CLOCKSOURCE_MASK(64), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; +#endif + +static u64 read_hv_clock_msr(struct clocksource *arg) +{ + u64 current_tick; + /* + * Read the partition counter to get the current tick count. This count + * is set to 0 when the partition is created and is incremented in + * 100 nanosecond units. + */ + rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick); + return current_tick; +} + +static struct clocksource hyperv_cs_msr = { + .name = "hyperv_clocksource_msr", + .rating = 400, + .read = read_hv_clock_msr, + .mask = CLOCKSOURCE_MASK(64), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; static void *hypercall_pg; /* @@ -31,6 +104,7 @@ static void *hypercall_pg; * hypervisor has been detected. * * 1. Setup the hypercall page. + * 2. Register Hyper-V specific clocksource. */ void hyperv_init(void) { @@ -58,6 +132,37 @@ void hyperv_init(void) hypercall_msr.enable = 1; hypercall_msr.guest_physical_address = vmalloc_to_pfn(hypercall_pg); wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); + + /* + * Register Hyper-V specific clocksource. + */ +#ifdef CONFIG_X86_64 + if (ms_hyperv.features & HV_X64_MSR_REFERENCE_TSC_AVAILABLE) { + union hv_x64_msr_hypercall_contents tsc_msr; + + tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL); + if (!tsc_pg) { + clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100); + return; + } + + rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64); + + tsc_msr.enable = 1; + tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg); + + wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64); + clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100); + return; + } +#endif + /* + * For 32 bit guests just use the MSR based mechanism for reading + * the partition counter. + */ + + if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE) + clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100); } /* |