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Subject[PATCH v6 03/17] KVM: SVM: Detect X2APIC virtualization (x2AVIC) support
Date
Add CPUID check for the x2APIC virtualization (x2AVIC) feature.
If available, the SVM driver can support both AVIC and x2AVIC modes
when load the kvm_amd driver with avic=1. The operating mode will be
determined at runtime depending on the guest APIC mode.

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
arch/x86/include/asm/svm.h | 3 +++
arch/x86/kvm/svm/avic.c | 45 ++++++++++++++++++++++++++++++++++++++
arch/x86/kvm/svm/svm.c | 15 ++-----------
arch/x86/kvm/svm/svm.h | 9 ++++++++
4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index f70a5108d464..2c2a104b777e 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -195,6 +195,9 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
#define AVIC_ENABLE_SHIFT 31
#define AVIC_ENABLE_MASK (1 << AVIC_ENABLE_SHIFT)

+#define X2APIC_MODE_SHIFT 30
+#define X2APIC_MODE_MASK (1 << X2APIC_MODE_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/avic.c b/arch/x86/kvm/svm/avic.c
index a8f514212b87..7d4e73e95acd 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -40,6 +40,9 @@
#define AVIC_GATAG_TO_VMID(x) ((x >> AVIC_VCPU_ID_BITS) & AVIC_VM_ID_MASK)
#define AVIC_GATAG_TO_VCPUID(x) (x & AVIC_VCPU_ID_MASK)

+static bool force_avic;
+module_param_unsafe(force_avic, bool, 0444);
+
/* Note:
* This hash table is used to map VM_ID to a struct kvm_svm,
* when handling AMD IOMMU GALOG notification to schedule in
@@ -50,6 +53,7 @@ static DEFINE_HASHTABLE(svm_vm_data_hash, SVM_VM_DATA_HASH_BITS);
static u32 next_vm_id = 0;
static bool next_vm_id_wrapped = 0;
static DEFINE_SPINLOCK(svm_vm_data_hash_lock);
+enum avic_modes avic_mode;

/*
* This is a wrapper of struct amd_iommu_ir_data.
@@ -1077,3 +1081,44 @@ void avic_vcpu_unblocking(struct kvm_vcpu *vcpu)

avic_vcpu_load(vcpu);
}
+
+/*
+ * Note:
+ * - The module param avic enable both xAPIC and x2APIC mode.
+ * - Hypervisor can support both xAVIC and x2AVIC in the same guest.
+ * - The mode can be switched at run-time.
+ */
+bool avic_hardware_setup(struct kvm_x86_ops *x86_ops)
+{
+ if (!npt_enabled)
+ return false;
+
+ if (boot_cpu_has(X86_FEATURE_AVIC)) {
+ avic_mode = AVIC_MODE_X1;
+ pr_info("AVIC enabled\n");
+ } else if (force_avic) {
+ /*
+ * Some older systems does not advertise AVIC support.
+ * See Revision Guide for specific AMD processor for more detail.
+ */
+ avic_mode = AVIC_MODE_X1;
+ pr_warn("AVIC is not supported in CPUID but force enabled");
+ pr_warn("Your system might crash and burn");
+ }
+
+ /* AVIC is a prerequisite for x2AVIC. */
+ if (boot_cpu_has(X86_FEATURE_X2AVIC)) {
+ if (avic_mode == AVIC_MODE_X1) {
+ avic_mode = AVIC_MODE_X2;
+ pr_info("x2AVIC enabled\n");
+ } else {
+ pr_warn(FW_BUG "Cannot support x2AVIC due to AVIC is disabled");
+ pr_warn(FW_BUG "Try enable AVIC using force_avic option");
+ }
+ }
+
+ if (avic_mode != AVIC_MODE_NONE)
+ amd_iommu_register_ga_log_notifier(&avic_ga_log_notifier);
+
+ return !!avic_mode;
+}
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index aa7b387e0b7c..196bca5751a1 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -188,9 +188,6 @@ module_param(tsc_scaling, int, 0444);
static bool avic;
module_param(avic, bool, 0444);

-static bool force_avic;
-module_param_unsafe(force_avic, bool, 0444);
-
bool __read_mostly dump_invalid_vmcb;
module_param(dump_invalid_vmcb, bool, 0644);

@@ -4913,17 +4910,9 @@ static __init int svm_hardware_setup(void)
nrips = false;
}

- enable_apicv = avic = avic && npt_enabled && (boot_cpu_has(X86_FEATURE_AVIC) || force_avic);
+ enable_apicv = avic = avic && avic_hardware_setup(&svm_x86_ops);

- if (enable_apicv) {
- if (!boot_cpu_has(X86_FEATURE_AVIC)) {
- pr_warn("AVIC is not supported in CPUID but force enabled");
- pr_warn("Your system might crash and burn");
- } else
- pr_info("AVIC enabled\n");
-
- amd_iommu_register_ga_log_notifier(&avic_ga_log_notifier);
- } else {
+ if (!enable_apicv) {
svm_x86_ops.vcpu_blocking = NULL;
svm_x86_ops.vcpu_unblocking = NULL;
svm_x86_ops.vcpu_get_apicv_inhibit_reasons = NULL;
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 32220a1b0ea2..1731c1f3884b 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -36,6 +36,14 @@ extern bool npt_enabled;
extern int vgif;
extern bool intercept_smi;

+enum avic_modes {
+ AVIC_MODE_NONE = 0,
+ AVIC_MODE_X1,
+ AVIC_MODE_X2,
+};
+
+extern enum avic_modes avic_mode;
+
/*
* Clean bits in VMCB.
* VMCB_ALL_CLEAN_MASK might also need to
@@ -603,6 +611,7 @@ extern struct kvm_x86_nested_ops svm_nested_ops;

/* avic.c */

+bool avic_hardware_setup(struct kvm_x86_ops *ops);
int avic_ga_log_notifier(u32 ga_tag);
void avic_vm_destroy(struct kvm *kvm);
int avic_vm_init(struct kvm *kvm);
--
2.25.1
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