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Subject[PATCH v4 15/23] KVM: x86: smm: check for failures on smm entry
Date
In the rare case of the failure on SMM entry, the KVM should at
least terminate the VM instead of going south.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
arch/x86/kvm/smm.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/smm.c b/arch/x86/kvm/smm.c
index b290ad14070f72..1191a79cf027e5 100644
--- a/arch/x86/kvm/smm.c
+++ b/arch/x86/kvm/smm.c
@@ -211,11 +211,17 @@ void enter_smm(struct kvm_vcpu *vcpu)
* Give enter_smm() a chance to make ISA-specific changes to the vCPU
* state (e.g. leave guest mode) after we've saved the state into the
* SMM state-save area.
+ *
+ * Kill the VM in the unlikely case of failure, because the VM
+ * can be in undefined state in this case.
*/
- static_call(kvm_x86_enter_smm)(vcpu, buf);
+ if (static_call(kvm_x86_enter_smm)(vcpu, buf))
+ goto error;

kvm_smm_changed(vcpu, true);
- kvm_vcpu_write_guest(vcpu, vcpu->arch.smbase + 0xfe00, buf, sizeof(buf));
+
+ if (kvm_vcpu_write_guest(vcpu, vcpu->arch.smbase + 0xfe00, buf, sizeof(buf)))
+ goto error;

if (static_call(kvm_x86_get_nmi_mask)(vcpu))
vcpu->arch.hflags |= HF_SMM_INSIDE_NMI_MASK;
@@ -235,7 +241,8 @@ void enter_smm(struct kvm_vcpu *vcpu)
dt.address = dt.size = 0;
static_call(kvm_x86_set_idt)(vcpu, &dt);

- kvm_set_dr(vcpu, 7, DR7_FIXED_1);
+ if (WARN_ON_ONCE(kvm_set_dr(vcpu, 7, DR7_FIXED_1)))
+ goto error;

cs.selector = (vcpu->arch.smbase >> 4) & 0xffff;
cs.base = vcpu->arch.smbase;
@@ -264,11 +271,15 @@ void enter_smm(struct kvm_vcpu *vcpu)

#ifdef CONFIG_X86_64
if (guest_cpuid_has(vcpu, X86_FEATURE_LM))
- static_call(kvm_x86_set_efer)(vcpu, 0);
+ if (static_call(kvm_x86_set_efer)(vcpu, 0))
+ goto error;
#endif

kvm_update_cpuid_runtime(vcpu);
kvm_mmu_reset_context(vcpu);
+ return;
+error:
+ kvm_vm_dead(vcpu->kvm);
}

static void rsm_set_desc_flags(struct kvm_segment *desc, u32 flags)
--
2.34.3
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