[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2 10/11] vmware: set cpu capabilities during platform initialization
On Thu, 2017-04-13 at 12:11 +0200, Juergen Gross wrote: > There is no need to set the same capabilities for each cpu > individually. This can be done for all cpus in platform initialization. Looks reasonable to me. Acked-by: Alok Kataria <akataria@xxxxxxxxxx> Thanks, Alok > > Cc: Alok Kataria <akataria@xxxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> > Cc: x86@xxxxxxxxxx > Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx > Signed-off-by: Juergen Gross <jgross@xxxxxxxx> > --- > arch/x86/kernel/cpu/vmware.c | 39 ++++++++++++++++++++------------------- > 1 file changed, 20 insertions(+), 19 deletions(-) > > diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c > index 22403a28caf5..40ed26852ebd 100644 > --- a/arch/x86/kernel/cpu/vmware.c > +++ b/arch/x86/kernel/cpu/vmware.c > @@ -113,6 +113,24 @@ static void __init vmware_paravirt_ops_setup(void) > #define vmware_paravirt_ops_setup() do {} while (0) > #endif > > +/* > + * 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. > + */ > +static void __init vmware_set_capabilities(void) > +{ > + setup_force_cpu_cap(X86_FEATURE_CONSTANT_TSC); > + setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE); > +} > + > static void __init vmware_platform_setup(void) > { > uint32_t eax, ebx, ecx, edx; > @@ -152,6 +170,8 @@ static void __init vmware_platform_setup(void) > #ifdef CONFIG_X86_IO_APIC > no_timer_check = 1; > #endif > + > + vmware_set_capabilities(); > } > > /* > @@ -176,24 +196,6 @@ static uint32_t __init vmware_platform(void) > return 0; > } > > -/* > - * 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. > - */ > -static void vmware_set_cpu_features(struct cpuinfo_x86 *c) > -{ > - set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC); > - set_cpu_cap(c, X86_FEATURE_TSC_RELIABLE); > -} > - > /* Checks if hypervisor supports x2apic without VT-D interrupt remapping. */ > static bool __init vmware_legacy_x2apic_available(void) > { > @@ -206,7 +208,6 @@ static bool __init vmware_legacy_x2apic_available(void) > const __refconst struct hypervisor_x86 x86_hyper_vmware = { > .name = "VMware", > .detect = vmware_platform, > - .set_cpu_features = vmware_set_cpu_features, > .init_platform = vmware_platform_setup, > .x2apic_available = vmware_legacy_x2apic_available, > }; _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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