Adds KVM_EXIT_IOAPIC_EOI which allows the kernel to EOI
level-triggered IOAPIC interrupts.
Uses a per VCPU exit bitmap to decide whether or not the IOAPIC needs
to be informed (which is identical to the EOI_EXIT_BITMAP field used
by modern x86 processors, but can also be used to elide kvm IOAPIC EOI
exits on older processors).
[Note: A prototype using ResampleFDs found that decoupling the EOI
from the VCPU's thread made it possible for the VCPU to not see a
recent EOI after reentering the guest. This does not match real
hardware.]
Compile tested for Intel x86.
Signed-off-by: Steve Rutherford <srutherf...@google.com>
---
Documentation/virtual/kvm/api.txt | 12 ++++++++++++
arch/x86/include/asm/kvm_host.h | 3 +++
arch/x86/kvm/lapic.c | 9 +++++++++
arch/x86/kvm/x86.c | 11 +++++++++++
include/linux/kvm_host.h | 2 +-
include/uapi/linux/kvm.h | 5 +++++
6 files changed, 41 insertions(+), 1 deletion(-)
diff --git a/Documentation/virtual/kvm/api.txt
b/Documentation/virtual/kvm/api.txt
index b655024..78d0ae8 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3302,6 +3302,18 @@ Valid values for 'type' are:
to ignore the request, or to gather VM memory core dump and/or
reset/shutdown of the VM.
+ /* KVM_EXIT_IOAPIC_EOI */
+ struct {
+ __u8 vector;
+ } eoi;
+
+Indicates that the VCPU's in-kernel local APIC received an EOI for a
+level-triggered IOAPIC interrupt. This exit only triggers when the
+IOAPIC is implemented in userspace (i.e. KVM_CAP_SPLIT_IRQCHIP is enabled);
+the userspace IOAPIC should process the EOI and retrigger the interrupt if
+it is still asserted. Vector is the LAPIC interrupt vector for which the
+EOI was received.
+
/* Fix the size of the union. */
char padding[256];
};
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 18a110b..f1e0103 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -560,6 +560,9 @@ struct kvm_vcpu_arch {
struct {
bool pv_unhalted;
} pv;
+
+ u64 eoi_exit_bitmaps[4];
+ int pending_ioapic_eoi;
};
struct kvm_lpage_info {
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 536b79e..37e220d 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -871,6 +871,15 @@ int kvm_apic_compare_prio(struct kvm_vcpu *vcpu1, struct
kvm_vcpu *vcpu2)
static void kvm_ioapic_send_eoi(struct kvm_lapic *apic, int vector)
{
+ if (irqchip_split(apic->vcpu->kvm)) {
+ if (test_bit(vector,
+ (void *) apic->vcpu->arch.eoi_exit_bitmaps)) {
+ apic->vcpu->arch.pending_ioapic_eoi = vector;
+ kvm_make_request(KVM_REQ_IOAPIC_EOI_EXIT, apic->vcpu);
+ }
+ return;
+ }
+
if (kvm_ioapic_handles_vector(apic->vcpu->kvm, vector)) {
int trigger_mode;
if (apic_test_vector(vector, apic->regs + APIC_TMR))
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 985c99f..a612266 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6277,6 +6277,17 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
kvm_pmu_handle_event(vcpu);
if (kvm_check_request(KVM_REQ_PMI, vcpu))
kvm_pmu_deliver_pmi(vcpu);
+ if (kvm_check_request(KVM_REQ_IOAPIC_EOI_EXIT, vcpu)) {
+ BUG_ON(vcpu->arch.pending_ioapic_eoi > 255);
+ if (test_bit(vcpu->arch.pending_ioapic_eoi,
+ (void *) vcpu->arch.eoi_exit_bitmaps)) {
+ vcpu->run->exit_reason = KVM_EXIT_IOAPIC_EOI;
+ vcpu->run->eoi.vector =
+ vcpu->arch.pending_ioapic_eoi;
+ r = 0;
+ goto out;
+ }
+ }
if (kvm_check_request(KVM_REQ_SCAN_IOAPIC, vcpu))
vcpu_scan_ioapic(vcpu);
if (kvm_check_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu))
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index f7eab09..8e12d67 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -140,6 +140,7 @@ static inline bool is_error_page(struct page *page)
#define KVM_REQ_APIC_PAGE_RELOAD 25
#define KVM_REQ_SMI 26
#define KVM_REQ_HV_CRASH 27
+#define KVM_REQ_IOAPIC_EOI_EXIT 28
#define KVM_USERSPACE_IRQ_SOURCE_ID 0
#define KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID 1
@@ -1157,4 +1158,3 @@ static inline void kvm_vcpu_set_dy_eligible(struct
kvm_vcpu *vcpu, bool val)
}
#endif /* CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */
#endif
-
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index e4304d0..c15f5d9 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -183,6 +183,7 @@ struct kvm_s390_skeys {
#define KVM_EXIT_EPR 23
#define KVM_EXIT_SYSTEM_EVENT 24
#define KVM_EXIT_S390_STSI 25
+#define KVM_EXIT_IOAPIC_EOI 26
/* For KVM_EXIT_INTERNAL_ERROR */
/* Emulate instruction failed. */
@@ -330,6 +331,10 @@ struct kvm_run {
__u8 sel1;
__u16 sel2;
} s390_stsi;
+ /* KVM_EXIT_IOAPIC_EOI */
+ struct {
+ __u8 vector;
+ } eoi;
/* Fix the size of the union. */
char padding[256];
};
--
2.5.0.rc2.392.g76e840b
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