diff options
| -rw-r--r-- | arch/x86/hyperv/hv_init.c | 2 | ||||
| -rw-r--r-- | drivers/clocksource/hyperv_timer.c | 44 | ||||
| -rw-r--r-- | include/clocksource/hyperv_timer.h | 1 |
3 files changed, 38 insertions, 9 deletions
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index a269049a43ce..a823fde1ad7f 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -462,6 +462,8 @@ void __init hyperv_init(void) BUG_ON(!src); memcpy_to_page(pg, 0, src, HV_HYP_PAGE_SIZE); memunmap(src); + + hv_remap_tsc_clocksource(); } else { hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg); wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c index 9445a1558fe9..c0cef92b12b8 100644 --- a/drivers/clocksource/hyperv_timer.c +++ b/drivers/clocksource/hyperv_timer.c @@ -509,9 +509,6 @@ static bool __init hv_init_tsc_clocksource(void) if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE)) return false; - if (hv_root_partition) - return false; - /* * If Hyper-V offers TSC_INVARIANT, then the virtualized TSC correctly * handles frequency and offset changes due to live migration, @@ -529,16 +526,28 @@ static bool __init hv_init_tsc_clocksource(void) } hv_read_reference_counter = read_hv_clock_tsc; - tsc_pfn = HVPFN_DOWN(virt_to_phys(tsc_page)); /* - * The Hyper-V TLFS specifies to preserve the value of reserved - * bits in registers. So read the existing value, preserve the - * low order 12 bits, and add in the guest physical address - * (which already has at least the low 12 bits set to zero since - * it is page aligned). Also set the "enable" bit, which is bit 0. + * TSC page mapping works differently in root compared to guest. + * - In guest partition the guest PFN has to be passed to the + * hypervisor. + * - In root partition it's other way around: it has to map the PFN + * provided by the hypervisor. + * But it can't be mapped right here as it's too early and MMU isn't + * ready yet. So, we only set the enable bit here and will remap the + * page later in hv_remap_tsc_clocksource(). + * + * It worth mentioning, that TSC clocksource read function + * (read_hv_clock_tsc) has a MSR-based fallback mechanism, used when + * TSC page is zeroed (which is the case until the PFN is remapped) and + * thus TSC clocksource will work even without the real TSC page + * mapped. */ tsc_msr.as_uint64 = hv_get_register(HV_REGISTER_REFERENCE_TSC); + if (hv_root_partition) + tsc_pfn = tsc_msr.pfn; + else + tsc_pfn = HVPFN_DOWN(virt_to_phys(tsc_page)); tsc_msr.enable = 1; tsc_msr.pfn = tsc_pfn; hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr.as_uint64); @@ -573,3 +582,20 @@ void __init hv_init_clocksource(void) hv_sched_clock_offset = hv_read_reference_counter(); hv_setup_sched_clock(read_hv_sched_clock_msr); } + +void __init hv_remap_tsc_clocksource(void) +{ + if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE)) + return; + + if (!hv_root_partition) { + WARN(1, "%s: attempt to remap TSC page in guest partition\n", + __func__); + return; + } + + tsc_page = memremap(tsc_pfn << HV_HYP_PAGE_SHIFT, sizeof(tsc_pg), + MEMREMAP_WB); + if (!tsc_page) + pr_err("Failed to remap Hyper-V TSC page.\n"); +} diff --git a/include/clocksource/hyperv_timer.h b/include/clocksource/hyperv_timer.h index 3078d23faaea..783701a2102d 100644 --- a/include/clocksource/hyperv_timer.h +++ b/include/clocksource/hyperv_timer.h @@ -31,6 +31,7 @@ extern void hv_stimer_global_cleanup(void); extern void hv_stimer0_isr(void); extern void hv_init_clocksource(void); +extern void hv_remap_tsc_clocksource(void); extern unsigned long hv_get_tsc_pfn(void); extern struct ms_hyperv_tsc_page *hv_get_tsc_page(void); |