[PATCH 4.19 14/37] KVM: x86: get smi pending status correctly

Greg Kroah-Hartman
2021-02-02T16:21:55Z

From: Jay Zhou <jianjay.zhou@huawei.com>

commit 1f7becf1b7e21794fc9d460765fe09679bc9b9e0 upstream.

The injection process of smi has two steps:

Qemu KVM
Step1:
cpu->interrupt_request &= \
~CPU_INTERRUPT_SMI;
kvm_vcpu_ioctl(cpu, KVM_SMI)

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

Step2:
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@huawei.com>
Signed-off-by: Shengen Zhuang <zhuangshengen@huawei.com>
Message-Id: <20210118084720.1585-1-jianjay.zhou@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kvm/x86.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -102,6 +102,7 @@ static u64 __read_mostly cr4_reserved_bi

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);
@@ -3499,6 +3500,10 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_
struct kvm_vcpu_events *events)
{
process_nmi(vcpu);
+
+ if (kvm_check_request(KVM_REQ_SMI, vcpu))
+ process_smi(vcpu);
+
/*
* FIXME: pass injected and pending separately. This is only
* needed for nested virtualization, whose state cannot be