Re: [PATCH v8 1/5] Revert "KVM: X86: Fix setup the virt_spin_lock_key before static key get initialized"

From: Wanpeng Li <kernellwp@gmail.com>
To: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"the arch/x86 maintainers" <x86@kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Radim Krcmar <rkrcmar@redhat.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Juergen Gross <jgross@suse.com>,
	Peter Zijlstra <peterz@infradead.org>,
	will@kernel.org, linux-hyperv@vger.kernel.org,
	kvm <kvm@vger.kernel.org>,
	mikelley@microsoft.com, "K. Y. Srinivasan" <kys@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	Sasha Levin <sashal@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v8 1/5] Revert "KVM: X86: Fix setup the virt_spin_lock_key before static key get initialized"
Date: Tue, 19 Nov 2019 15:00:13 +0800	[thread overview]
Message-ID: <CANRm+Cyr+Gg06MiE1+6g9eKTcrN=nn9mPf6=b+5xUN5_9T0v4A@mail.gmail.com> (raw)
In-Reply-To: <1571829384-5309-2-git-send-email-zhenzhong.duan@oracle.com>

On Wed, 23 Oct 2019 at 19:20, Zhenzhong Duan <zhenzhong.duan@oracle.com> wrote:
>
> This reverts commit 34226b6b70980a8f81fff3c09a2c889f77edeeff.
>
> Commit 8990cac6e5ea ("x86/jump_label: Initialize static branching
> early") adds jump_label_init() call in setup_arch() to make static
> keys initialized early, so we could use the original simpler code
> again.
>
> The similar change for XEN is in commit 090d54bcbc54 ("Revert
> "x86/paravirt: Set up the virt_spin_lock_key after static keys get
> initialized"")
>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krcmar <rkrcmar@redhat.com>
> Cc: Sean Christopherson <sean.j.christopherson@intel.com>
> Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
> Cc: Wanpeng Li <wanpengli@tencent.com>
> Cc: Jim Mattson <jmattson@google.com>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: "H. Peter Anvin" <hpa@zytor.com>

Reviewed-by: Wanpeng Li <wanpengli@tencent.com>

> ---
>  arch/x86/kernel/kvm.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index e820568..3bc6a266 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -527,13 +527,6 @@ static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
>         }
>  }
>
> -static void __init kvm_smp_prepare_cpus(unsigned int max_cpus)
> -{
> -       native_smp_prepare_cpus(max_cpus);
> -       if (kvm_para_has_hint(KVM_HINTS_REALTIME))
> -               static_branch_disable(&virt_spin_lock_key);
> -}
> -
>  static void __init kvm_smp_prepare_boot_cpu(void)
>  {
>         /*
> @@ -633,7 +626,6 @@ static void __init kvm_guest_init(void)
>                 apic_set_eoi_write(kvm_guest_apic_eoi_write);
>
>  #ifdef CONFIG_SMP
> -       smp_ops.smp_prepare_cpus = kvm_smp_prepare_cpus;
>         smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
>         if (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
>             !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
> @@ -835,8 +827,10 @@ void __init kvm_spinlock_init(void)
>         if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
>                 return;
>
> -       if (kvm_para_has_hint(KVM_HINTS_REALTIME))
> +       if (kvm_para_has_hint(KVM_HINTS_REALTIME)) {
> +               static_branch_disable(&virt_spin_lock_key);
>                 return;
> +       }
>
>         /* Don't use the pvqspinlock code if there is only 1 vCPU. */
>         if (num_possible_cpus() == 1)
> --
> 1.8.3.1
>