[PATCH 4.19 07/57] KVM: x86: handle !lapic_in_kernel case in kvm_cpu_*_extint

From: Greg Kroah-Hartman
Date: Tue Dec 01 2020 - 04:01:09 EST


From: Paolo Bonzini <pbonzini@xxxxxxxxxx>

commit 72c3bcdcda494cbd600712a32e67702cdee60c07 upstream.

Centralize handling of interrupts from the userspace APIC
in kvm_cpu_has_extint and kvm_cpu_get_extint, since
userspace APIC interrupts are handled more or less the
same as ExtINTs are with split irqchip. This removes
duplicated code from kvm_cpu_has_injectable_intr and
kvm_cpu_has_interrupt, and makes the code more similar
between kvm_cpu_has_{extint,interrupt} on one side
and kvm_cpu_get_{extint,interrupt} on the other.

Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Filippo Sironi <sironi@xxxxxxxxx>
Reviewed-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Tested-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
arch/x86/kvm/irq.c | 83 ++++++++++++++++++++-------------------------------
arch/x86/kvm/lapic.c | 2 -
2 files changed, 34 insertions(+), 51 deletions(-)

--- a/arch/x86/kvm/irq.c
+++ b/arch/x86/kvm/irq.c
@@ -54,27 +54,8 @@ static int pending_userspace_extint(stru
*/
static int kvm_cpu_has_extint(struct kvm_vcpu *v)
{
- u8 accept = kvm_apic_accept_pic_intr(v);
-
- if (accept) {
- if (irqchip_split(v->kvm))
- return pending_userspace_extint(v);
- else
- return v->kvm->arch.vpic->output;
- } else
- return 0;
-}
-
-/*
- * check if there is injectable interrupt:
- * when virtual interrupt delivery enabled,
- * interrupt from apic will handled by hardware,
- * we don't need to check it here.
- */
-int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v)
-{
/*
- * FIXME: interrupt.injected represents an interrupt that it's
+ * FIXME: interrupt.injected represents an interrupt whose
* side-effects have already been applied (e.g. bit from IRR
* already moved to ISR). Therefore, it is incorrect to rely
* on interrupt.injected to know if there is a pending
@@ -87,6 +68,23 @@ int kvm_cpu_has_injectable_intr(struct k
if (!lapic_in_kernel(v))
return v->arch.interrupt.injected;

+ if (!kvm_apic_accept_pic_intr(v))
+ return 0;
+
+ if (irqchip_split(v->kvm))
+ return pending_userspace_extint(v);
+ else
+ return v->kvm->arch.vpic->output;
+}
+
+/*
+ * check if there is injectable interrupt:
+ * when virtual interrupt delivery enabled,
+ * interrupt from apic will handled by hardware,
+ * we don't need to check it here.
+ */
+int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v)
+{
if (kvm_cpu_has_extint(v))
return 1;

@@ -102,20 +100,6 @@ int kvm_cpu_has_injectable_intr(struct k
*/
int kvm_cpu_has_interrupt(struct kvm_vcpu *v)
{
- /*
- * FIXME: interrupt.injected represents an interrupt that it's
- * side-effects have already been applied (e.g. bit from IRR
- * already moved to ISR). Therefore, it is incorrect to rely
- * on interrupt.injected to know if there is a pending
- * interrupt in the user-mode LAPIC.
- * This leads to nVMX/nSVM not be able to distinguish
- * if it should exit from L2 to L1 on EXTERNAL_INTERRUPT on
- * pending interrupt or should re-inject an injected
- * interrupt.
- */
- if (!lapic_in_kernel(v))
- return v->arch.interrupt.injected;
-
if (kvm_cpu_has_extint(v))
return 1;

@@ -129,16 +113,21 @@ EXPORT_SYMBOL_GPL(kvm_cpu_has_interrupt)
*/
static int kvm_cpu_get_extint(struct kvm_vcpu *v)
{
- if (kvm_cpu_has_extint(v)) {
- if (irqchip_split(v->kvm)) {
- int vector = v->arch.pending_external_vector;
-
- v->arch.pending_external_vector = -1;
- return vector;
- } else
- return kvm_pic_read_irq(v->kvm); /* PIC */
- } else
+ if (!kvm_cpu_has_extint(v)) {
+ WARN_ON(!lapic_in_kernel(v));
return -1;
+ }
+
+ if (!lapic_in_kernel(v))
+ return v->arch.interrupt.nr;
+
+ if (irqchip_split(v->kvm)) {
+ int vector = v->arch.pending_external_vector;
+
+ v->arch.pending_external_vector = -1;
+ return vector;
+ } else
+ return kvm_pic_read_irq(v->kvm); /* PIC */
}

/*
@@ -146,13 +135,7 @@ static int kvm_cpu_get_extint(struct kvm
*/
int kvm_cpu_get_interrupt(struct kvm_vcpu *v)
{
- int vector;
-
- if (!lapic_in_kernel(v))
- return v->arch.interrupt.nr;
-
- vector = kvm_cpu_get_extint(v);
-
+ int vector = kvm_cpu_get_extint(v);
if (vector != -1)
return vector; /* PIC */

--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2284,7 +2284,7 @@ int kvm_apic_has_interrupt(struct kvm_vc
struct kvm_lapic *apic = vcpu->arch.apic;
u32 ppr;

- if (!kvm_apic_hw_enabled(apic))
+ if (!kvm_apic_present(vcpu))
return -1;

__apic_update_ppr(apic, &ppr);