diff options
| -rw-r--r-- | arch/x86/include/asm/vmware.h | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/hypervisor.c | 11 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/vmware.c | 18 | ||||
| -rw-r--r-- | arch/x86/kernel/tsc_sync.c | 8 |
4 files changed, 36 insertions, 2 deletions
diff --git a/arch/x86/include/asm/vmware.h b/arch/x86/include/asm/vmware.h index 02dfea5aebc..c11b7e100d8 100644 --- a/arch/x86/include/asm/vmware.h +++ b/arch/x86/include/asm/vmware.h @@ -22,5 +22,6 @@ extern unsigned long vmware_get_tsc_khz(void); extern int vmware_platform(void); +extern void vmware_set_feature_bits(struct cpuinfo_x86 *c); #endif diff --git a/arch/x86/kernel/cpu/hypervisor.c b/arch/x86/kernel/cpu/hypervisor.c index 7bd55064ffe..35ae2b75226 100644 --- a/arch/x86/kernel/cpu/hypervisor.c +++ b/arch/x86/kernel/cpu/hypervisor.c @@ -41,8 +41,17 @@ unsigned long get_hypervisor_tsc_freq(void) return 0; } +static inline void __cpuinit +hypervisor_set_feature_bits(struct cpuinfo_x86 *c) +{ + if (boot_cpu_data.x86_hyper_vendor == X86_HYPER_VENDOR_VMWARE) { + vmware_set_feature_bits(c); + return; + } +} + void __cpuinit init_hypervisor(struct cpuinfo_x86 *c) { detect_hypervisor_vendor(c); + hypervisor_set_feature_bits(c); } - diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c index d5d1b75a4b7..2ac4394fcb9 100644 --- a/arch/x86/kernel/cpu/vmware.c +++ b/arch/x86/kernel/cpu/vmware.c @@ -86,3 +86,21 @@ unsigned long vmware_get_tsc_khz(void) BUG_ON(!vmware_platform()); return __vmware_get_tsc_khz(); } + +/* + * VMware hypervisor takes care of exporting a reliable TSC to the guest. + * Still, due to timing difference when running on virtual cpus, the TSC can + * be marked as unstable in some cases. For example, the TSC sync check at + * bootup can fail due to a marginal offset between vcpus' TSCs (though the + * TSCs do not drift from each other). Also, the ACPI PM timer clocksource + * is not suitable as a watchdog when running on a hypervisor because the + * kernel may miss a wrap of the counter if the vcpu is descheduled for a + * long time. To skip these checks at runtime we set these capability bits, + * so that the kernel could just trust the hypervisor with providing a + * reliable virtual TSC that is suitable for timekeeping. + */ +void __cpuinit vmware_set_feature_bits(struct cpuinfo_x86 *c) +{ + set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC); + set_cpu_cap(c, X86_FEATURE_TSC_RELIABLE); +} diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c index 9ffb01c31c4..5977c40a138 100644 --- a/arch/x86/kernel/tsc_sync.c +++ b/arch/x86/kernel/tsc_sync.c @@ -108,6 +108,12 @@ void __cpuinit check_tsc_sync_source(int cpu) if (unsynchronized_tsc()) return; + if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE)) { + printk(KERN_INFO + "Skipping synchronization checks as TSC is reliable.\n"); + return; + } + printk(KERN_INFO "checking TSC synchronization [CPU#%d -> CPU#%d]:", smp_processor_id(), cpu); @@ -161,7 +167,7 @@ void __cpuinit check_tsc_sync_target(void) { int cpus = 2; - if (unsynchronized_tsc()) + if (unsynchronized_tsc() || boot_cpu_has(X86_FEATURE_TSC_RELIABLE)) return; /* |