linux-kernel - [PATCH 06/13] KVM: SVM: Add VNMI bit definition

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Date:   Thu, 17 Nov 2022 16:32:35 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sandipan Das <sandipan.das@....com>,
        Daniel Sneddon <daniel.sneddon@...ux.intel.com>,
        Jing Liu <jing2.liu@...el.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Wyes Karny <wyes.karny@....com>,
        Borislav Petkov <bp@...en8.de>,
        Babu Moger <babu.moger@....com>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Jim Mattson <jmattson@...gle.com>, x86@...nel.org,
        Maxim Levitsky <mlevitsk@...hat.com>,
        Santosh Shukla <santosh.shukla@....com>
Subject: [PATCH 06/13] KVM: SVM: Add VNMI bit definition

From: Santosh Shukla <santosh.shukla@....com>

VNMI exposes 3 capability bits (V_NMI, V_NMI_MASK, and V_NMI_ENABLE) to
virtualize NMI and NMI_MASK, Those capability bits are part of
VMCB::intr_ctrl -
V_NMI(11) - Indicates whether a virtual NMI is pending in the guest.
V_NMI_MASK(12) - Indicates whether virtual NMI is masked in the guest.
V_NMI_ENABLE(26) - Enables the NMI virtualization feature for the guest.

When Hypervisor wants to inject NMI, it will set V_NMI bit, Processor
will clear the V_NMI bit and Set the V_NMI_MASK which means the Guest is
handling NMI, After the guest handled the NMI, The processor will clear
the V_NMI_MASK on the successful completion of IRET instruction Or if
VMEXIT occurs while delivering the virtual NMI.

To enable the VNMI capability, Hypervisor need to program
V_NMI_ENABLE bit 1.

Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>
Signed-off-by: Santosh Shukla <santosh.shukla@....com>
---
 arch/x86/include/asm/svm.h | 7 +++++++
 arch/x86/kvm/svm/svm.c     | 6 ++++++
 2 files changed, 13 insertions(+)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 4352b46dd20c90..d8474e4b04ac05 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -198,6 +198,13 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
 #define X2APIC_MODE_SHIFT 30
 #define X2APIC_MODE_MASK (1 << X2APIC_MODE_SHIFT)
 
+#define V_NMI_PENDING_SHIFT 11
+#define V_NMI_PENDING (1 << V_NMI_PENDING_SHIFT)
+#define V_NMI_MASK_SHIFT 12
+#define V_NMI_MASK (1 << V_NMI_MASK_SHIFT)
+#define V_NMI_ENABLE_SHIFT 26
+#define V_NMI_ENABLE (1 << V_NMI_ENABLE_SHIFT)
+
 #define LBR_CTL_ENABLE_MASK BIT_ULL(0)
 #define VIRTUAL_VMLOAD_VMSAVE_ENABLE_MASK BIT_ULL(1)
 
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 03acbe8ff34edb..08a7b2a0a29f3a 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -230,6 +230,8 @@ module_param(dump_invalid_vmcb, bool, 0644);
 bool intercept_smi = true;
 module_param(intercept_smi, bool, 0444);
 
+bool vnmi = true;
+module_param(vnmi, bool, 0444);
 
 static bool svm_gp_erratum_intercept = true;
 
@@ -5029,6 +5031,10 @@ static __init int svm_hardware_setup(void)
 		svm_x86_ops.vcpu_get_apicv_inhibit_reasons = NULL;
 	}
 
+	vnmi = vnmi && boot_cpu_has(X86_FEATURE_AMD_VNMI);
+	if (vnmi)
+		pr_info("Virtual NMI enabled\n");
+
 	if (vls) {
 		if (!npt_enabled ||
 		    !boot_cpu_has(X86_FEATURE_V_VMSAVE_VMLOAD) ||
-- 
2.34.3