Re: [PATCH v2 39/50] KVM: x86: Move CPU compat checks hook to kvm_x86_ops (from kvm_x86_init_ops)

[Huang, Kai]

On Wed, 2022-11-30 at 23:09 +0000, Sean Christopherson wrote:
> Move the .check_processor_compatibility() callback from kvm_x86_init_ops
> to kvm_x86_ops to allow a future patch to do compatibility checks during
> CPU hotplug.
> 
> Do kvm_ops_update() before compat checks so that static_call() can be
> used during compat checks.
> 
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>

Reviewed-by: Kai Huang <kai.huang@xxxxxxxxx>

> ---
>  arch/x86/include/asm/kvm-x86-ops.h |  1 +
>  arch/x86/include/asm/kvm_host.h    |  3 ++-
>  arch/x86/kvm/svm/svm.c             |  5 +++--
>  arch/x86/kvm/vmx/vmx.c             | 16 +++++++--------
>  arch/x86/kvm/x86.c                 | 31 +++++++++++-------------------
>  5 files changed, 25 insertions(+), 31 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
> index abccd51dcfca..dba2909e5ae2 100644
> --- a/arch/x86/include/asm/kvm-x86-ops.h
> +++ b/arch/x86/include/asm/kvm-x86-ops.h
> @@ -14,6 +14,7 @@ BUILD_BUG_ON(1)
>   * to make a definition optional, but in this case the default will
>   * be __static_call_return0.
>   */
> +KVM_X86_OP(check_processor_compatibility)
>  KVM_X86_OP(hardware_enable)
>  KVM_X86_OP(hardware_disable)
>  KVM_X86_OP(hardware_unsetup)
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index d79aedf70908..ba74fea6850b 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1518,6 +1518,8 @@ static inline u16 kvm_lapic_irq_dest_mode(bool dest_mode_logical)
>  struct kvm_x86_ops {
>  	const char *name;
>  
> +	int (*check_processor_compatibility)(void);
> +
>  	int (*hardware_enable)(void);
>  	void (*hardware_disable)(void);
>  	void (*hardware_unsetup)(void);
> @@ -1729,7 +1731,6 @@ struct kvm_x86_nested_ops {
>  };
>  
>  struct kvm_x86_init_ops {
> -	int (*check_processor_compatibility)(void);
>  	int (*hardware_setup)(void);
>  	unsigned int (*handle_intel_pt_intr)(void);
>  
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 9f94efcb9aa6..c2e95c0d9fd8 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -543,7 +543,7 @@ static bool kvm_is_svm_supported(void)
>  	return true;
>  }
>  
> -static int __init svm_check_processor_compat(void)
> +static int svm_check_processor_compat(void)
>  {
>  	if (!kvm_is_svm_supported())
>  		return -EIO;
> @@ -4695,6 +4695,8 @@ static int svm_vm_init(struct kvm *kvm)
>  static struct kvm_x86_ops svm_x86_ops __initdata = {
>  	.name = KBUILD_MODNAME,
>  
> +	.check_processor_compatibility = svm_check_processor_compat,
> +
>  	.hardware_unsetup = svm_hardware_unsetup,
>  	.hardware_enable = svm_hardware_enable,
>  	.hardware_disable = svm_hardware_disable,
> @@ -5079,7 +5081,6 @@ static __init int svm_hardware_setup(void)
>  
>  static struct kvm_x86_init_ops svm_init_ops __initdata = {
>  	.hardware_setup = svm_hardware_setup,
> -	.check_processor_compatibility = svm_check_processor_compat,
>  
>  	.runtime_ops = &svm_x86_ops,
>  	.pmu_ops = &amd_pmu_ops,
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 2a8a6e481c76..6416ed5b7f89 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -2520,8 +2520,7 @@ static bool cpu_has_perf_global_ctrl_bug(void)
>  	return false;
>  }
>  
> -static __init int adjust_vmx_controls(u32 ctl_min, u32 ctl_opt,
> -				      u32 msr, u32 *result)
> +static int adjust_vmx_controls(u32 ctl_min, u32 ctl_opt, u32 msr, u32 *result)
>  {
>  	u32 vmx_msr_low, vmx_msr_high;
>  	u32 ctl = ctl_min | ctl_opt;
> @@ -2539,7 +2538,7 @@ static __init int adjust_vmx_controls(u32 ctl_min, u32 ctl_opt,
>  	return 0;
>  }
>  
> -static __init u64 adjust_vmx_controls64(u64 ctl_opt, u32 msr)
> +static u64 adjust_vmx_controls64(u64 ctl_opt, u32 msr)
>  {
>  	u64 allowed;
>  
> @@ -2548,8 +2547,8 @@ static __init u64 adjust_vmx_controls64(u64 ctl_opt, u32 msr)
>  	return  ctl_opt & allowed;
>  }
>  
> -static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
> -				    struct vmx_capability *vmx_cap)
> +static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
> +			     struct vmx_capability *vmx_cap)
>  {
>  	u32 vmx_msr_low, vmx_msr_high;
>  	u32 _pin_based_exec_control = 0;
> @@ -2710,7 +2709,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
>  	return 0;
>  }
>  
> -static bool __init kvm_is_vmx_supported(void)
> +static bool kvm_is_vmx_supported(void)
>  {
>  	if (!cpu_has_vmx()) {
>  		pr_err("CPU doesn't support VMX\n");
> @@ -2726,7 +2725,7 @@ static bool __init kvm_is_vmx_supported(void)
>  	return true;
>  }
>  
> -static int __init vmx_check_processor_compat(void)
> +static int vmx_check_processor_compat(void)
>  {
>  	struct vmcs_config vmcs_conf;
>  	struct vmx_capability vmx_cap;
> @@ -8104,6 +8103,8 @@ static void vmx_vm_destroy(struct kvm *kvm)
>  static struct kvm_x86_ops vmx_x86_ops __initdata = {
>  	.name = KBUILD_MODNAME,
>  
> +	.check_processor_compatibility = vmx_check_processor_compat,
> +
>  	.hardware_unsetup = vmx_hardware_unsetup,
>  
>  	.hardware_enable = vmx_hardware_enable,
> @@ -8501,7 +8502,6 @@ static __init int hardware_setup(void)
>  }
>  
>  static struct kvm_x86_init_ops vmx_init_ops __initdata = {
> -	.check_processor_compatibility = vmx_check_processor_compat,
>  	.hardware_setup = hardware_setup,
>  	.handle_intel_pt_intr = NULL,
>  
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 5551f3552f08..ee9af412ffd4 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -9279,12 +9279,7 @@ static inline void kvm_ops_update(struct kvm_x86_init_ops *ops)
>  	kvm_pmu_ops_update(ops->pmu_ops);
>  }
>  
> -struct kvm_cpu_compat_check {
> -	struct kvm_x86_init_ops *ops;
> -	int *ret;
> -};
> -
> -static int kvm_x86_check_processor_compatibility(struct kvm_x86_init_ops *ops)
> +static int kvm_x86_check_processor_compatibility(void)
>  {
>  	struct cpuinfo_x86 *c = &cpu_data(smp_processor_id());
>  
> @@ -9294,19 +9289,16 @@ static int kvm_x86_check_processor_compatibility(struct kvm_x86_init_ops *ops)
>  	    __cr4_reserved_bits(cpu_has, &boot_cpu_data))
>  		return -EIO;
>  
> -	return ops->check_processor_compatibility();
> +	return static_call(kvm_x86_check_processor_compatibility)();
>  }
>  
> -static void kvm_x86_check_cpu_compat(void *data)
> +static void kvm_x86_check_cpu_compat(void *ret)
>  {
> -	struct kvm_cpu_compat_check *c = data;
> -
> -	*c->ret = kvm_x86_check_processor_compatibility(c->ops);
> +	*(int *)ret = kvm_x86_check_processor_compatibility();
>  }
>  
>  static int __kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
>  {
> -	struct kvm_cpu_compat_check c;
>  	u64 host_pat;
>  	int r, cpu;
>  
> @@ -9377,12 +9369,12 @@ static int __kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
>  	if (r != 0)
>  		goto out_mmu_exit;
>  
> -	c.ret = &r;
> -	c.ops = ops;
> +	kvm_ops_update(ops);
> +
>  	for_each_online_cpu(cpu) {
> -		smp_call_function_single(cpu, kvm_x86_check_cpu_compat, &c, 1);
> +		smp_call_function_single(cpu, kvm_x86_check_cpu_compat, &r, 1);
>  		if (r < 0)
> -			goto out_hardware_unsetup;
> +			goto out_unwind_ops;
>  	}
>  
>  	/*
> @@ -9390,8 +9382,6 @@ static int __kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
>  	 * absolutely necessary, as most operations from this point forward
>  	 * require unwinding.
>  	 */
> -	kvm_ops_update(ops);
> -
>  	kvm_timer_init();
>  
>  	if (pi_inject_timer == -1)
> @@ -9427,8 +9417,9 @@ static int __kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
>  	kvm_init_msr_list();
>  	return 0;
>  
> -out_hardware_unsetup:
> -	ops->runtime_ops->hardware_unsetup();
> +out_unwind_ops:
> +	kvm_x86_ops.hardware_enable = NULL;
> +	static_call(kvm_x86_hardware_unsetup)();
>  out_mmu_exit:
>  	kvm_mmu_vendor_module_exit();
>  out_free_percpu: