[PATCH] KVM: x86: get smi pending status correctly

From: Jay Zhou
Date: Mon Jan 18 2021 - 03:49:22 EST

The injection process of smi has two steps:

Qemu KVM
cpu->interrupt_request &= \
kvm_vcpu_ioctl(cpu, KVM_SMI)

call kvm_vcpu_ioctl_smi() and
kvm_make_request(KVM_REQ_SMI, vcpu);

kvm_vcpu_ioctl(cpu, KVM_RUN, 0)

call process_smi() if
kvm_check_request(KVM_REQ_SMI, vcpu) is
true, mark vcpu->arch.smi_pending = true;

The vcpu->arch.smi_pending will be set true in step2, unfortunately if
vcpu paused between step1 and step2, the kvm_run->immediate_exit will be
set and vcpu has to exit to Qemu immediately during step2 before mark
vcpu->arch.smi_pending true.
During VM migration, Qemu will get the smi pending status from KVM using
KVM_GET_VCPU_EVENTS ioctl at the downtime, then the smi pending status
will be lost.

Signed-off-by: Jay Zhou <jianjay.zhou@xxxxxxxxxx>
Signed-off-by: Shengen Zhuang <zhuangshengen@xxxxxxxxxx>
arch/x86/kvm/x86.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9a8969a..9025c76 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -105,6 +105,7 @@

static void update_cr8_intercept(struct kvm_vcpu *vcpu);
static void process_nmi(struct kvm_vcpu *vcpu);
+static void process_smi(struct kvm_vcpu *vcpu);
static void enter_smm(struct kvm_vcpu *vcpu);
static void __kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags);
static void store_regs(struct kvm_vcpu *vcpu);
@@ -4230,6 +4231,9 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,

+ if (kvm_check_request(KVM_REQ_SMI, vcpu))
+ process_smi(vcpu);
* In guest mode, payload delivery should be deferred,
* so that the L1 hypervisor can intercept #PF before