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x86: KVM guest: Try using new kvm clock msrs

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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 <glommer@redhat.com>
Acked-by: Zachary Amsden <zamsden@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Glauber Costa 2010-05-11 12:17:44 -04:00 committed by Avi Kivity
parent 84478c829d
commit 838815a787
1 changed files with 32 additions and 21 deletions
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53
arch/x86/kernel/kvmclock.c
View file

@ -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";
}