From 838815a78785022f6611e5c48386567aea7b818b Mon Sep 17 00:00:00 2001 From: Glauber Costa Date: Tue, 11 May 2010 12:17:44 -0400 Subject: x86: KVM guest: Try using new kvm clock msrs We now added a new set of clock-related msrs in replacement of the old ones. In theory, we could just try to use them and get a return value indicating they do not exist, due to our use of kvm_write_msr_save. However, kvm clock registration happens very early, and if we ever try to write to a non-existant MSR, we raise a lethal #GP, since our idt handlers are not in place yet. So this patch tests for a cpuid feature exported by the host to decide which set of msrs are supported. Signed-off-by: Glauber Costa Acked-by: Zachary Amsden Signed-off-by: Marcelo Tosatti --- arch/x86/kernel/kvmclock.c | 53 ++++++++++++++++++++++++++++------------------ 1 file changed, 32 insertions(+), 21 deletions(-) diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index feaeb0d..59c740f 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -29,6 +29,8 @@ #define KVM_SCALE 22 static int kvmclock = 1; +static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME; +static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK; static int parse_no_kvmclock(char *arg) { @@ -54,7 +56,8 @@ static unsigned long kvm_get_wallclock(void) low = (int)__pa_symbol(&wall_clock); high = ((u64)__pa_symbol(&wall_clock) >> 32); - native_write_msr(MSR_KVM_WALL_CLOCK, low, high); + + native_write_msr(msr_kvm_wall_clock, low, high); vcpu_time = &get_cpu_var(hv_clock); pvclock_read_wallclock(&wall_clock, vcpu_time, &ts); @@ -130,7 +133,8 @@ static int kvm_register_clock(char *txt) high = ((u64)__pa(&per_cpu(hv_clock, cpu)) >> 32); printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n", cpu, high, low, txt); - return native_write_msr_safe(MSR_KVM_SYSTEM_TIME, low, high); + + return native_write_msr_safe(msr_kvm_system_time, low, high); } #ifdef CONFIG_X86_LOCAL_APIC @@ -165,14 +169,14 @@ static void __init kvm_smp_prepare_boot_cpu(void) #ifdef CONFIG_KEXEC static void kvm_crash_shutdown(struct pt_regs *regs) { - native_write_msr_safe(MSR_KVM_SYSTEM_TIME, 0, 0); + native_write_msr(msr_kvm_system_time, 0, 0); native_machine_crash_shutdown(regs); } #endif static void kvm_shutdown(void) { - native_write_msr_safe(MSR_KVM_SYSTEM_TIME, 0, 0); + native_write_msr(msr_kvm_system_time, 0, 0); native_machine_shutdown(); } @@ -181,27 +185,34 @@ void __init kvmclock_init(void) if (!kvm_para_available()) return; - if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)) { - if (kvm_register_clock("boot clock")) - return; - pv_time_ops.sched_clock = kvm_clock_read; - x86_platform.calibrate_tsc = kvm_get_tsc_khz; - x86_platform.get_wallclock = kvm_get_wallclock; - x86_platform.set_wallclock = kvm_set_wallclock; + if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) { + msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW; + msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW; + } else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE))) + return; + + printk(KERN_INFO "kvm-clock: Using msrs %x and %x", + msr_kvm_system_time, msr_kvm_wall_clock); + + if (kvm_register_clock("boot clock")) + return; + pv_time_ops.sched_clock = kvm_clock_read; + x86_platform.calibrate_tsc = kvm_get_tsc_khz; + x86_platform.get_wallclock = kvm_get_wallclock; + x86_platform.set_wallclock = kvm_set_wallclock; #ifdef CONFIG_X86_LOCAL_APIC - x86_cpuinit.setup_percpu_clockev = - kvm_setup_secondary_clock; + x86_cpuinit.setup_percpu_clockev = + kvm_setup_secondary_clock; #endif #ifdef CONFIG_SMP - smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; + smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; #endif - machine_ops.shutdown = kvm_shutdown; + machine_ops.shutdown = kvm_shutdown; #ifdef CONFIG_KEXEC - machine_ops.crash_shutdown = kvm_crash_shutdown; + machine_ops.crash_shutdown = kvm_crash_shutdown; #endif - kvm_get_preset_lpj(); - clocksource_register(&kvm_clock); - pv_info.paravirt_enabled = 1; - pv_info.name = "KVM"; - } + kvm_get_preset_lpj(); + clocksource_register(&kvm_clock); + pv_info.paravirt_enabled = 1; + pv_info.name = "KVM"; } -- cgit v1.1