KVM: nVMX: Add nested msr load/restore algorithm
Several hypervisors need MSR auto load/restore feature.
We read MSRs from VM-entry MSR load area which specified by L1,
and load them via kvm_set_msr in the nested entry.
When nested exit occurs, we get MSRs via kvm_get_msr, writing
them to L1`s MSR store area. After this, we read MSRs from VM-exit
MSR load area, and load them via kvm_set_msr.
Signed-off-by: Wincy Van <fanwenyi0529@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/include/uapi/asm/vmx.h b/arch/x86/include/uapi/asm/vmx.h
index b813bf9..ff2b8e2 100644
--- a/arch/x86/include/uapi/asm/vmx.h
+++ b/arch/x86/include/uapi/asm/vmx.h
@@ -56,6 +56,7 @@
#define EXIT_REASON_MSR_READ 31
#define EXIT_REASON_MSR_WRITE 32
#define EXIT_REASON_INVALID_STATE 33
+#define EXIT_REASON_MSR_LOAD_FAIL 34
#define EXIT_REASON_MWAIT_INSTRUCTION 36
#define EXIT_REASON_MONITOR_INSTRUCTION 39
#define EXIT_REASON_PAUSE_INSTRUCTION 40
@@ -116,10 +117,14 @@
{ EXIT_REASON_APIC_WRITE, "APIC_WRITE" }, \
{ EXIT_REASON_EOI_INDUCED, "EOI_INDUCED" }, \
{ EXIT_REASON_INVALID_STATE, "INVALID_STATE" }, \
+ { EXIT_REASON_MSR_LOAD_FAIL, "MSR_LOAD_FAIL" }, \
{ EXIT_REASON_INVD, "INVD" }, \
{ EXIT_REASON_INVVPID, "INVVPID" }, \
{ EXIT_REASON_INVPCID, "INVPCID" }, \
{ EXIT_REASON_XSAVES, "XSAVES" }, \
{ EXIT_REASON_XRSTORS, "XRSTORS" }
+#define VMX_ABORT_SAVE_GUEST_MSR_FAIL 1
+#define VMX_ABORT_LOAD_HOST_MSR_FAIL 4
+
#endif /* _UAPIVMX_H */
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index d4c58d8..9137d2b 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6143,6 +6143,13 @@
*/
}
+static void nested_vmx_abort(struct kvm_vcpu *vcpu, u32 indicator)
+{
+ /* TODO: not to reset guest simply here. */
+ kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
+ pr_warn("kvm: nested vmx abort, indicator %d\n", indicator);
+}
+
static enum hrtimer_restart vmx_preemption_timer_fn(struct hrtimer *timer)
{
struct vcpu_vmx *vmx =
@@ -8286,6 +8293,67 @@
ns_to_ktime(preemption_timeout), HRTIMER_MODE_REL);
}
+static inline int nested_vmx_msr_check_common(struct vmx_msr_entry *e)
+{
+ if (e->index >> 8 == 0x8 || e->reserved != 0)
+ return -EINVAL;
+ return 0;
+}
+
+static inline int nested_vmx_load_msr_check(struct vmx_msr_entry *e)
+{
+ if (e->index == MSR_FS_BASE ||
+ e->index == MSR_GS_BASE ||
+ nested_vmx_msr_check_common(e))
+ return -EINVAL;
+ return 0;
+}
+
+/*
+ * Load guest's/host's msr at nested entry/exit.
+ * return 0 for success, entry index for failure.
+ */
+static u32 nested_vmx_load_msr(struct kvm_vcpu *vcpu, u64 gpa, u32 count)
+{
+ u32 i;
+ struct vmx_msr_entry e;
+ struct msr_data msr;
+
+ msr.host_initiated = false;
+ for (i = 0; i < count; i++) {
+ kvm_read_guest(vcpu->kvm, gpa + i * sizeof(e), &e, sizeof(e));
+ if (nested_vmx_load_msr_check(&e))
+ goto fail;
+ msr.index = e.index;
+ msr.data = e.value;
+ if (kvm_set_msr(vcpu, &msr))
+ goto fail;
+ }
+ return 0;
+fail:
+ return i + 1;
+}
+
+static int nested_vmx_store_msr(struct kvm_vcpu *vcpu, u64 gpa, u32 count)
+{
+ u32 i;
+ struct vmx_msr_entry e;
+
+ for (i = 0; i < count; i++) {
+ kvm_read_guest(vcpu->kvm, gpa + i * sizeof(e),
+ &e, 2 * sizeof(u32));
+ if (nested_vmx_msr_check_common(&e))
+ return -EINVAL;
+ if (kvm_get_msr(vcpu, e.index, &e.value))
+ return -EINVAL;
+ kvm_write_guest(vcpu->kvm,
+ gpa + i * sizeof(e) +
+ offsetof(struct vmx_msr_entry, value),
+ &e.value, sizeof(e.value));
+ }
+ return 0;
+}
+
/*
* prepare_vmcs02 is called when the L1 guest hypervisor runs its nested
* L2 guest. L1 has a vmcs for L2 (vmcs12), and this function "merges" it
@@ -8582,6 +8650,7 @@
int cpu;
struct loaded_vmcs *vmcs02;
bool ia32e;
+ u32 msr_entry_idx;
if (!nested_vmx_check_permission(vcpu) ||
!nested_vmx_check_vmcs12(vcpu))
@@ -8629,15 +8698,6 @@
return 1;
}
- if (vmcs12->vm_entry_msr_load_count > 0 ||
- vmcs12->vm_exit_msr_load_count > 0 ||
- vmcs12->vm_exit_msr_store_count > 0) {
- pr_warn_ratelimited("%s: VMCS MSR_{LOAD,STORE} unsupported\n",
- __func__);
- nested_vmx_failValid(vcpu, VMXERR_ENTRY_INVALID_CONTROL_FIELD);
- return 1;
- }
-
if (!vmx_control_verify(vmcs12->cpu_based_vm_exec_control,
nested_vmx_true_procbased_ctls_low,
nested_vmx_procbased_ctls_high) ||
@@ -8739,10 +8799,21 @@
vmx_segment_cache_clear(vmx);
- vmcs12->launch_state = 1;
-
prepare_vmcs02(vcpu, vmcs12);
+ msr_entry_idx = nested_vmx_load_msr(vcpu,
+ vmcs12->vm_entry_msr_load_addr,
+ vmcs12->vm_entry_msr_load_count);
+ if (msr_entry_idx) {
+ leave_guest_mode(vcpu);
+ vmx_load_vmcs01(vcpu);
+ nested_vmx_entry_failure(vcpu, vmcs12,
+ EXIT_REASON_MSR_LOAD_FAIL, msr_entry_idx);
+ return 1;
+ }
+
+ vmcs12->launch_state = 1;
+
if (vmcs12->guest_activity_state == GUEST_ACTIVITY_HLT)
return kvm_emulate_halt(vcpu);
@@ -9172,6 +9243,10 @@
kvm_set_dr(vcpu, 7, 0x400);
vmcs_write64(GUEST_IA32_DEBUGCTL, 0);
+
+ if (nested_vmx_load_msr(vcpu, vmcs12->vm_exit_msr_load_addr,
+ vmcs12->vm_exit_msr_load_count))
+ nested_vmx_abort(vcpu, VMX_ABORT_LOAD_HOST_MSR_FAIL);
}
/*
@@ -9193,6 +9268,10 @@
prepare_vmcs12(vcpu, vmcs12, exit_reason, exit_intr_info,
exit_qualification);
+ if (nested_vmx_store_msr(vcpu, vmcs12->vm_exit_msr_store_addr,
+ vmcs12->vm_exit_msr_store_count))
+ nested_vmx_abort(vcpu, VMX_ABORT_SAVE_GUEST_MSR_FAIL);
+
vmx_load_vmcs01(vcpu);
if ((exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c259814..af9faed 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2324,6 +2324,7 @@
{
return kvm_x86_ops->get_msr(vcpu, msr_index, pdata);
}
+EXPORT_SYMBOL_GPL(kvm_get_msr);
static int get_msr_mtrr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
{
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1cc6e2e..167e8c1 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1593,6 +1593,7 @@
}
return 0;
}
+EXPORT_SYMBOL_GPL(kvm_write_guest);
int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
gpa_t gpa, unsigned long len)