linux-kernel - [PATCH v8 7/9] KVM: Move kvm_arch_vcpu

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Date:   Mon, 11 Apr 2022 17:04:45 +0800
From:   Zeng Guang <guang.zeng@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Tony Luck <tony.luck@...el.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Kim Phillips <kim.phillips@....com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Jethro Beekman <jethro@...tanix.com>,
        Kai Huang <kai.huang@...el.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Robert Hu <robert.hu@...el.com>, Gao Chao <chao.gao@...el.com>,
        Zeng Guang <guang.zeng@...el.com>
Subject: [PATCH v8 7/9] KVM: Move kvm_arch_vcpu_precreate() under kvm->lock

Arch specific KVM common data may require pre-allocation or other
preprocess ready before vCPU creation at runtime. It's safe to
invoke kvm_arch_vcpu_precreate() within the protection of kvm->lock
directly rather than take into account in the implementation for each
architecture.

Suggested-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Zeng Guang <guang.zeng@...el.com>
---
 arch/s390/kvm/kvm-s390.c | 2 --
 virt/kvm/kvm_main.c      | 2 +-
 2 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 156d1c25a3c1..5c795bbcf1ea 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -3042,9 +3042,7 @@ static int sca_can_add_vcpu(struct kvm *kvm, unsigned int id)
 	if (!sclp.has_esca || !sclp.has_64bscao)
 		return false;
 
-	mutex_lock(&kvm->lock);
 	rc = kvm->arch.use_esca ? 0 : sca_switch_to_extended(kvm);
-	mutex_unlock(&kvm->lock);
 
 	return rc == 0 && id < KVM_S390_ESCA_CPU_SLOTS;
 }
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 70e05af5ebea..a452e678a015 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3732,9 +3732,9 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
 	}
 
 	kvm->created_vcpus++;
+	r = kvm_arch_vcpu_precreate(kvm, id);
 	mutex_unlock(&kvm->lock);
 
-	r = kvm_arch_vcpu_precreate(kvm, id);
 	if (r)
 		goto vcpu_decrement;
 
-- 
2.27.0