[Qemu-devel] [PATCH] kvm: notify host when guest paniced

[Wen Congyang]

We can know the guest is paniced when the guest runs on xen.
But we do not have such feature on kvm. This patch implemnts
this feature, and the implementation is the same as xen:
register panic notifier, and call hypercall when the guest
is paniced.

Signed-off-by: Wen Congyang <address@hidden>
---
 arch/x86/kernel/kvm.c    |   12 ++++++++++++
 arch/x86/kvm/svm.c       |    8 ++++++--
 arch/x86/kvm/vmx.c       |    8 ++++++--
 arch/x86/kvm/x86.c       |   13 +++++++++++--
 include/linux/kvm.h      |    1 +
 include/linux/kvm_para.h |    1 +
 6 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index f0c6fd6..b928d1d 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -331,6 +331,17 @@ static struct notifier_block kvm_pv_reboot_nb = {
        .notifier_call = kvm_pv_reboot_notify,
 };
 
+static int
+kvm_pv_panic_notify(struct notifier_block *nb, unsigned long code, void 
*unused)
+{
+       kvm_hypercall0(KVM_HC_GUEST_PANIC);
+       return NOTIFY_DONE;
+}
+
+static struct notifier_block kvm_pv_panic_nb = {
+       .notifier_call = kvm_pv_panic_notify,
+};
+
 static u64 kvm_steal_clock(int cpu)
 {
        u64 steal;
@@ -417,6 +428,7 @@ void __init kvm_guest_init(void)
 
        paravirt_ops_setup();
        register_reboot_notifier(&kvm_pv_reboot_nb);
+       atomic_notifier_chain_register(&panic_notifier_list, &kvm_pv_panic_nb);
        for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
                spin_lock_init(&async_pf_sleepers[i].lock);
        if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 0b7690e..38b4705 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1900,10 +1900,14 @@ static int halt_interception(struct vcpu_svm *svm)
 
 static int vmmcall_interception(struct vcpu_svm *svm)
 {
+       int ret;
+
        svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
        skip_emulated_instruction(&svm->vcpu);
-       kvm_emulate_hypercall(&svm->vcpu);
-       return 1;
+       ret = kvm_emulate_hypercall(&svm->vcpu);
+
+       /* Ignore the error? */
+       return ret == 0 ? 0 : 1;
 }
 
 static unsigned long nested_svm_get_tdp_cr3(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 66147ca..1b57ebb 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4582,9 +4582,13 @@ static int handle_halt(struct kvm_vcpu *vcpu)
 
 static int handle_vmcall(struct kvm_vcpu *vcpu)
 {
+       int ret;
+
        skip_emulated_instruction(vcpu);
-       kvm_emulate_hypercall(vcpu);
-       return 1;
+       ret = kvm_emulate_hypercall(vcpu);
+
+       /* Ignore the error? */
+       return ret == 0 ? 0 : 1;
 }
 
 static int handle_invd(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c9d99e5..3fc2853 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4923,7 +4923,7 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
        u64 param, ingpa, outgpa, ret;
        uint16_t code, rep_idx, rep_cnt, res = HV_STATUS_SUCCESS, rep_done = 0;
        bool fast, longmode;
-       int cs_db, cs_l;
+       int cs_db, cs_l, r = 1;
 
        /*
         * hypercall generates UD from non zero cpl and real mode
@@ -4964,6 +4964,10 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
        case HV_X64_HV_NOTIFY_LONG_SPIN_WAIT:
                kvm_vcpu_on_spin(vcpu);
                break;
+       case KVM_HC_GUEST_PANIC:
+               vcpu->run->exit_reason = KVM_EXIT_GUEST_PANIC;
+               r = 0;
+               break;
        default:
                res = HV_STATUS_INVALID_HYPERCALL_CODE;
                break;
@@ -4977,7 +4981,7 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
                kvm_register_write(vcpu, VCPU_REGS_RAX, ret & 0xffffffff);
        }
 
-       return 1;
+       return r;
 }
 
 int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
@@ -5013,6 +5017,11 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
        case KVM_HC_VAPIC_POLL_IRQ:
                ret = 0;
                break;
+       case KVM_HC_GUEST_PANIC:
+               ret = 0;
+               vcpu->run->exit_reason = KVM_EXIT_GUEST_PANIC;
+               r = 0;
+               break;
        default:
                ret = -KVM_ENOSYS;
                break;
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index acbe429..8f0e31b 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -163,6 +163,7 @@ struct kvm_pit_config {
 #define KVM_EXIT_OSI              18
 #define KVM_EXIT_PAPR_HCALL      19
 #define KVM_EXIT_S390_UCONTROL   20
+#define KVM_EXIT_GUEST_PANIC     21
 
 /* For KVM_EXIT_INTERNAL_ERROR */
 #define KVM_INTERNAL_ERROR_EMULATION 1
diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h
index ff476dd..cf94023 100644
--- a/include/linux/kvm_para.h
+++ b/include/linux/kvm_para.h
@@ -19,6 +19,7 @@
 #define KVM_HC_MMU_OP                  2
 #define KVM_HC_FEATURES                        3
 #define KVM_HC_PPC_MAP_MAGIC_PAGE      4
+#define KVM_HC_GUEST_PANIC             5
 
 /*
  * hypercalls use architecture specific
-- 
1.7.1