On Fri, Nov 04, 2022, Yuan Yao wrote:
> On Wed, Nov 02, 2022 at 11:18:35PM +0000, Sean Christopherson wrote:
> > To avoid having to unwind various setup, e.g registration of several
> > notifiers, slot in the vendor hardware setup before the registration of
> > said notifiers and callbacks. Introducing a functional change while
> > moving code is less than ideal, but the alternative is adding a pile of
> > unwinding code, which is much more error prone, e.g. several attempts to
> > move the setup code verbatim all introduced bugs.
...
> > @@ -9325,6 +9343,24 @@ int kvm_arch_init(void *opaque)
> > kvm_caps.supported_xcr0 = host_xcr0 & KVM_SUPPORTED_XCR0;
> > }
> >
> > + rdmsrl_safe(MSR_EFER, &host_efer);
> > +
> > + if (boot_cpu_has(X86_FEATURE_XSAVES))
> > + rdmsrl(MSR_IA32_XSS, host_xss);
> > +
> > + kvm_init_pmu_capability();
> > +
> > + r = ops->hardware_setup();
> > + if (r != 0)
> > + goto out_mmu_exit;
>
> The failure case of ops->hardware_setup() is unwound
> by kvm_arch_exit() before this patch, do we need to
> keep that old behavior ?
As called out in the changelog, the call to ops->hardware_setup() was deliberately
slotted in before the call to kvm_timer_init() so that kvm_arch_init() wouldn't
need to unwind more stuff if harware_setup() fails.
> > + /*
> > + * Point of no return! DO NOT add error paths below this point unless
> > + * absolutely necessary, as most operations from this point forward
> > + * require unwinding.
> > + */
> > + kvm_ops_update(ops);
> > +
> > kvm_timer_init();
> >
> > if (pi_inject_timer == -1)
> > @@ -9336,8 +9372,32 @@ int kvm_arch_init(void *opaque)
> > set_hv_tscchange_cb(kvm_hyperv_tsc_notifier);
> > #endif
> >
> > + kvm_register_perf_callbacks(ops->handle_intel_pt_intr);
> > +
> > + if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
> > + kvm_caps.supported_xss = 0;
> > +
> > +#define __kvm_cpu_cap_has(UNUSED_, f) kvm_cpu_cap_has(f)
> > + cr4_reserved_bits = __cr4_reserved_bits(__kvm_cpu_cap_has, UNUSED_);
> > +#undef __kvm_cpu_cap_has
> > +
> > + if (kvm_caps.has_tsc_control) {
> > + /*
> > + * Make sure the user can only configure tsc_khz values that
> > + * fit into a signed integer.
> > + * A min value is not calculated because it will always
> > + * be 1 on all machines.
> > + */
> > + u64 max = min(0x7fffffffULL,
> > + __scale_tsc(kvm_caps.max_tsc_scaling_ratio, tsc_khz));
> > + kvm_caps.max_guest_tsc_khz = max;
> > + }
> > + kvm_caps.default_tsc_scaling_ratio = 1ULL << kvm_caps.tsc_scaling_ratio_frac_bits;
> > + kvm_init_msr_list();
> > return 0;
> >
> > +out_mmu_exit:
> > + kvm_mmu_vendor_module_exit();
> > out_free_percpu:
> > free_percpu(user_return_msrs);
> > out_free_x86_emulator_cache:
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