linux-kernel - [PATCH v4 5/6] KVM: x86: allow per cpu apicv inhibit reasons

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Date:   Tue, 22 Mar 2022 19:40:49 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Joerg Roedel <joro@...tes.org>,
        linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Jim Mattson <jmattson@...gle.com>, x86@...nel.org,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v4 5/6] KVM: x86: allow per cpu apicv inhibit reasons

Add optional callback .vcpu_get_apicv_inhibit_reasons returning
extra inhibit reasons that prevent APICv from working on this vCPU.

Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/include/asm/kvm-x86-ops.h |  1 +
 arch/x86/include/asm/kvm_host.h    |  6 ++++++
 arch/x86/kvm/x86.c                 | 14 ++++++++++++--
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index 3c368b639c04..96e4e9842dfc 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -126,6 +126,7 @@ KVM_X86_OP_OPTIONAL(migrate_timers)
 KVM_X86_OP(msr_filter_changed)
 KVM_X86_OP(complete_emulated_msr)
 KVM_X86_OP(vcpu_deliver_sipi_vector)
+KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons);
 
 #undef KVM_X86_OP
 #undef KVM_X86_OP_OPTIONAL
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9694dd5e6ccc..1c87a6e9e99f 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1507,6 +1507,11 @@ struct kvm_x86_ops {
 	int (*complete_emulated_msr)(struct kvm_vcpu *vcpu, int err);
 
 	void (*vcpu_deliver_sipi_vector)(struct kvm_vcpu *vcpu, u8 vector);
+
+	/*
+	 * Returns vCPU specific APICv inhibit reasons
+	 */
+	unsigned long (*vcpu_get_apicv_inhibit_reasons)(struct kvm_vcpu *vcpu);
 };
 
 struct kvm_x86_nested_ops {
@@ -1807,6 +1812,7 @@ gpa_t kvm_mmu_gva_to_gpa_system(struct kvm_vcpu *vcpu, gva_t gva,
 				struct x86_exception *exception);
 
 bool kvm_apicv_activated(struct kvm *kvm);
+bool kvm_vcpu_apicv_activated(struct kvm_vcpu *vcpu);
 void kvm_vcpu_update_apicv(struct kvm_vcpu *vcpu);
 void __kvm_set_or_clear_apicv_inhibit(struct kvm *kvm,
 				      enum kvm_apicv_inhibit reason, bool set);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9c27239f987f..d52af860843d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9114,6 +9114,14 @@ bool kvm_apicv_activated(struct kvm *kvm)
 }
 EXPORT_SYMBOL_GPL(kvm_apicv_activated);
 
+bool kvm_vcpu_apicv_activated(struct kvm_vcpu *vcpu)
+{
+	ulong vm_reasons = READ_ONCE(vcpu->kvm->arch.apicv_inhibit_reasons);
+	ulong vcpu_reasons = static_call(kvm_x86_vcpu_get_apicv_inhibit_reasons)(vcpu);
+
+	return (vm_reasons | vcpu_reasons) == 0;
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_apicv_activated);
 
 static void set_or_clear_apicv_inhibit(unsigned long *inhibits,
 				       enum kvm_apicv_inhibit reason, bool set)
@@ -9788,7 +9796,8 @@ void kvm_vcpu_update_apicv(struct kvm_vcpu *vcpu)
 
 	down_read(&vcpu->kvm->arch.apicv_update_lock);
 
-	activate = kvm_apicv_activated(vcpu->kvm);
+	activate = kvm_vcpu_apicv_activated(vcpu);
+
 	if (vcpu->arch.apicv_active == activate)
 		goto out;
 
@@ -10189,7 +10198,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 		 * per-VM state, and responsing vCPUs must wait for the update
 		 * to complete before servicing KVM_REQ_APICV_UPDATE.
 		 */
-		WARN_ON_ONCE(kvm_apicv_activated(vcpu->kvm) != kvm_vcpu_apicv_active(vcpu));
+		WARN_ON_ONCE(kvm_vcpu_apicv_activated(vcpu) != kvm_vcpu_apicv_active(vcpu));
+
 
 		exit_fastpath = static_call(kvm_x86_vcpu_run)(vcpu);
 		if (likely(exit_fastpath != EXIT_FASTPATH_REENTER_GUEST))
-- 
2.26.3