On Mon, Apr 26, 2010 at 01:46:27PM -0400, Glauber Costa wrote:
> 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@xxxxxxxxxx>
> ---
> arch/x86/kernel/kvmclock.c | 56 +++++++++++++++++++++++++++----------------
> 1 files changed, 35 insertions(+), 21 deletions(-)
>
> diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
> index feaeb0d..f2f6aee 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)
> {
> @@ -41,6 +43,7 @@ early_param("no-kvmclock", parse_no_kvmclock);
> static DEFINE_PER_CPU_SHARED_ALIGNED(struct pvclock_vcpu_time_info, hv_clock);
> static struct pvclock_wall_clock wall_clock;
>
> +
Extra newline.
> /*
> * The wallclock is the time of day when we booted. Since then, some time may
> * have elapsed since the hypervisor wrote the data. So we try to account for
> @@ -54,7 +57,8 @@ 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_safe(msr_kvm_wall_clock, low, high);
>
> vcpu_time = &get_cpu_var(hv_clock);
> pvclock_read_wallclock(&wall_clock, vcpu_time, &ts);
> @@ -130,7 +134,8 @@ 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 +170,15 @@ 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 +187,35 @@ 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;
Non conformant indentation.
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