[PATCH 07/13] KVM: SVM: Add VNMI support in get/set_nmi_mask

Maxim Levitsky
2022-11-17T14:34:57Z

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

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.

Maxim:
- made set_vnmi_mask/clear_vnmi_mask/is_vnmi_mask warn if called
without vNMI enabled
- clear IRET intercept in svm_set_nmi_mask even with vNMI

Signed-off-by: Santosh Shukla <santosh.shukla@amd.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
arch/x86/kvm/svm/svm.c | 18 ++++++++++++++-
arch/x86/kvm/svm/svm.h | 52 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 08a7b2a0a29f3a..c16f68f6c4f7d7 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3618,13 +3618,29 @@ 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 (masked)
+ set_vnmi_mask(svm);
+ else {
+ clear_vnmi_mask(svm);
+ if (!sev_es_guest(vcpu->kvm))
+ svm_clr_intercept(svm, INTERCEPT_IRET);
+ }
+ 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 f5383104d00580..bf7f4851dee204 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,
@@ -531,6 +532,57 @@ 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 (!WARN_ON_ONCE(!vmcb))
+ return false;
+
+ return !!(vmcb->control.int_ctl & V_NMI_MASK);
+}
+
+static inline void set_vnmi_mask(struct vcpu_svm *svm)
+{
+ struct vmcb *vmcb = get_vnmi_vmcb(svm);
+
+ if (!WARN_ON_ONCE(!vmcb))
+ return;
+
+ vmcb->control.int_ctl |= V_NMI_MASK;
+}
+
+static inline void clear_vnmi_mask(struct vcpu_svm *svm)
+{
+ struct vmcb *vmcb = get_vnmi_vmcb(svm);
+
+ if (!WARN_ON_ONCE(!vmcb))
+ return;
+
+ vmcb->control.int_ctl &= ~V_NMI_MASK;
+}
+
/* svm.c */
#define MSR_INVALID 0xffffffffU

--
2.34.3