[PATCHv3 3/8] KVM: SVM: Add VNMI support in get/set_nmi_mask

From: Santosh Shukla
Date: Wed Aug 10 2022 - 02:14:52 EST


VMCB intr_ctrl bit12 (V_NMI_MASK) is set by the processor when handling
NMI in guest and is cleared after the NMI is handled. Treat V_NMI_MASK
as read-only in the hypervisor except for the SMM case where hypervisor
before entring and after leaving SMM mode requires to set and unset
V_NMI_MASK.

Adding API(get_vnmi_vmcb) in order to return the correct vmcb for L1 or
L2, and also API(clear/set_vnmi_mask) to clear and set mask.

Signed-off-by: Santosh Shukla <santosh.shukla@xxxxxxx>
---
v3:
* Handle SMM case
* Added set/clear_vnmi_mask() API.

v2:
- Added get_vnmi_vmcb API to return vmcb for l1 and l2.
- Use get_vnmi_vmcb to get correct vmcb in func -
is_vnmi_enabled/_mask_set()
- removed vnmi check from is_vnmi_enabled() func.

arch/x86/kvm/svm/svm.c | 17 +++++++++++++-
arch/x86/kvm/svm/svm.h | 52 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 0259b909ed16..f0ac197fd965 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3621,13 +3621,28 @@ static int svm_nmi_allowed(struct kvm_vcpu *vcpu, bool for_injection)

static bool svm_get_nmi_mask(struct kvm_vcpu *vcpu)
{
- return !!(vcpu->arch.hflags & HF_NMI_MASK);
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ if (is_vnmi_enabled(svm))
+ return is_vnmi_mask_set(svm);
+ else
+ return !!(vcpu->arch.hflags & HF_NMI_MASK);
}

static void svm_set_nmi_mask(struct kvm_vcpu *vcpu, bool masked)
{
struct vcpu_svm *svm = to_svm(vcpu);

+ if (is_vnmi_enabled(svm)) {
+ if (is_smm(vcpu)) {
+ if (masked)
+ set_vnmi_mask(svm);
+ else
+ clear_vnmi_mask(svm);
+ }
+ return;
+ }
+
if (masked) {
vcpu->arch.hflags |= HF_NMI_MASK;
if (!sev_es_guest(vcpu->kvm))
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 6a7686bf6900..cc98ec7bd119 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -35,6 +35,7 @@ extern u32 msrpm_offsets[MSRPM_OFFSETS] __read_mostly;
extern bool npt_enabled;
extern int vgif;
extern bool intercept_smi;
+extern bool vnmi;

enum avic_modes {
AVIC_MODE_NONE = 0,
@@ -532,6 +533,57 @@ static inline bool is_x2apic_msrpm_offset(u32 offset)
(msr < (APIC_BASE_MSR + 0x100));
}

+static inline struct vmcb *get_vnmi_vmcb(struct vcpu_svm *svm)
+{
+ if (!vnmi)
+ return NULL;
+
+ if (is_guest_mode(&svm->vcpu))
+ return svm->nested.vmcb02.ptr;
+ else
+ return svm->vmcb01.ptr;
+}
+
+static inline bool is_vnmi_enabled(struct vcpu_svm *svm)
+{
+ struct vmcb *vmcb = get_vnmi_vmcb(svm);
+
+ if (vmcb)
+ return !!(vmcb->control.int_ctl & V_NMI_ENABLE);
+ else
+ return false;
+}
+
+static inline bool is_vnmi_mask_set(struct vcpu_svm *svm)
+{
+ struct vmcb *vmcb = get_vnmi_vmcb(svm);
+
+ if (vmcb)
+ return !!(vmcb->control.int_ctl & V_NMI_MASK);
+ else
+ return false;
+}
+
+static inline void set_vnmi_mask(struct vcpu_svm *svm)
+{
+ struct vmcb *vmcb = get_vnmi_vmcb(svm);
+
+ if (vmcb)
+ vmcb->control.int_ctl |= V_NMI_MASK;
+ else
+ svm->vcpu.arch.hflags |= HF_GIF_MASK;
+}
+
+static inline void clear_vnmi_mask(struct vcpu_svm *svm)
+{
+ struct vmcb *vmcb = get_vnmi_vmcb(svm);
+
+ if (vmcb)
+ vmcb->control.int_ctl &= ~V_NMI_MASK;
+ else
+ svm->vcpu.arch.hflags &= ~HF_GIF_MASK;
+}
+
/* svm.c */
#define MSR_INVALID 0xffffffffU

--
2.25.1