[PATCHv5 2/8] KVM: SVM: Add VNMI bit definition

Santosh Shukla
2022-10-27T08:40:09Z

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@redhat.com>
Signed-off-by: Santosh Shukla <santosh.shukla@amd.com>
---
v5:
- Renamed s/X86_FEATURE_V_NMI/X86_FEATURE_AMD_VNMI

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 0361626841bc..73bf97e04fe3 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 58f0077d9357..b759f650fe2d 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -229,6 +229,8 @@ 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;

@@ -5054,6 +5056,10 @@ 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) ||
--
2.25.1