linux-kernel - [PATCH 6/7] KVM: nSVM: implement nested VNMI

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Date:   Thu, 2 Jun 2022 19:56:19 +0530
From:   Santosh Shukla <santosh.shukla@....com>
To:     Paolo Bonzini <pbonzini@...hat.com>
CC:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Tom Lendacky <thomas.lendacky@....com>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <Santosh.Shukla@....com>
Subject: [PATCH 6/7] KVM: nSVM: implement nested VNMI

Currently nested_vmcb02_prepare_control func checks and programs bits
(V_TPR,_INTR, _IRQ) in nested mode, To support nested VNMI,
extending the check for VNMI bits if VNMI is enabled.

Tested with the KVM-unit-test that is developed for this purpose.

Signed-off-by: Santosh Shukla <santosh.shukla@....com>
---
 arch/x86/kvm/svm/nested.c | 8 ++++++++
 arch/x86/kvm/svm/svm.c    | 5 +++++
 arch/x86/kvm/svm/svm.h    | 1 +
 3 files changed, 14 insertions(+)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index bed5e1692cef..ce83739bae50 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -608,6 +608,11 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12
 	}
 }
 
+static inline bool nested_vnmi_enabled(struct vcpu_svm *svm)
+{
+	return svm->vnmi_enabled && (svm->nested.ctl.int_ctl & V_NMI_ENABLE);
+}
+
 static void nested_vmcb02_prepare_control(struct vcpu_svm *svm)
 {
 	u32 int_ctl_vmcb01_bits = V_INTR_MASKING_MASK;
@@ -627,6 +632,9 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm)
 	else
 		int_ctl_vmcb01_bits |= (V_GIF_MASK | V_GIF_ENABLE_MASK);
 
+	if (nested_vnmi_enabled(svm))
+		int_ctl_vmcb12_bits |= (V_NMI_PENDING | V_NMI_ENABLE);
+
 	/* Copied from vmcb01.  msrpm_base can be overwritten later.  */
 	vmcb02->control.nested_ctl = vmcb01->control.nested_ctl;
 	vmcb02->control.iopm_base_pa = vmcb01->control.iopm_base_pa;
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 200f979169e0..c91af728420b 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4075,6 +4075,8 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 
 	svm->vgif_enabled = vgif && guest_cpuid_has(vcpu, X86_FEATURE_VGIF);
 
+	svm->vnmi_enabled = vnmi && guest_cpuid_has(vcpu, X86_FEATURE_V_NMI);
+
 	svm_recalc_instruction_intercepts(vcpu, svm);
 
 	/* For sev guests, the memory encryption bit is not reserved in CR3.  */
@@ -4831,6 +4833,9 @@ static __init void svm_set_cpu_caps(void)
 		if (vgif)
 			kvm_cpu_cap_set(X86_FEATURE_VGIF);
 
+		if (vnmi)
+			kvm_cpu_cap_set(X86_FEATURE_V_NMI);
+
 		/* Nested VM can receive #VMEXIT instead of triggering #GP */
 		kvm_cpu_cap_set(X86_FEATURE_SVME_ADDR_CHK);
 	}
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 21c5460e947a..f926c77bf857 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -240,6 +240,7 @@ struct vcpu_svm {
 	bool pause_filter_enabled         : 1;
 	bool pause_threshold_enabled      : 1;
 	bool vgif_enabled                 : 1;
+	bool vnmi_enabled                 : 1;
 
 	u32 ldr_reg;
 	u32 dfr_reg;
-- 
2.25.1