[Qemu-devel] [PATCH 2/2] ppc/xics: preserve P and Q bits for KVM IRQs

[Sam Bobroff <sam.bobroff@au1.ibm.com>]

Kernel commit 17d48610ae0f ("KVM: PPC: Book 3S: XICS: Implement ICS
P/Q states") added new bits to the state used by KVM IRQs. Currently,
QEMU does not preserve these bits, so migrating (or otherwise saving
and restoring) the guest state causes the P and Q bits to be cleared.

Clearing the P bit has no effect, because the kernel will set it based
on other data, but the loss of a set Q bit will cause a lost
interrupt.

This patch preserves the P and Q bits, correcting the problem.

Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
---
 hw/intc/xics_kvm.c    | 12 ++++++++++++
 include/hw/ppc/xics.h |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
index 03c1fc77cb..dd93531ae3 100644
--- a/hw/intc/xics_kvm.c
+++ b/hw/intc/xics_kvm.c
@@ -229,6 +229,12 @@ static void ics_get_kvm_state(ICSState *ics)
                     | XICS_STATUS_REJECTED;
             }
         }
+        if (state & KVM_XICS_PRESENTED) {
+                irq->status |= XICS_STATUS_PRESENTED;
+        }
+        if (state & KVM_XICS_QUEUED) {
+                irq->status |= XICS_STATUS_QUEUED;
+        }
     }
 }
 
@@ -266,6 +272,12 @@ static int ics_set_kvm_state(ICSState *ics, int version_id)
                 state |= KVM_XICS_PENDING;
             }
         }
+        if (irq->status & XICS_STATUS_PRESENTED) {
+                state |= KVM_XICS_PRESENTED;
+        }
+        if (irq->status & XICS_STATUS_QUEUED) {
+                state |= KVM_XICS_QUEUED;
+        }
 
         ret = ioctl(kernel_xics_fd, KVM_SET_DEVICE_ATTR, &attr);
         if (ret != 0) {
diff --git a/include/hw/ppc/xics.h b/include/hw/ppc/xics.h
index 9a5e715fe5..36c79eb45c 100644
--- a/include/hw/ppc/xics.h
+++ b/include/hw/ppc/xics.h
@@ -131,6 +131,8 @@ struct ICSIRQState {
 #define XICS_STATUS_SENT               0x2
 #define XICS_STATUS_REJECTED           0x4
 #define XICS_STATUS_MASKED_PENDING     0x8
+#define XICS_STATUS_PRESENTED          0x10
+#define XICS_STATUS_QUEUED             0x20
     uint8_t status;
 /* (flags & XICS_FLAGS_IRQ_MASK) == 0 means the interrupt is not allocated */
 #define XICS_FLAGS_IRQ_LSI             0x1
-- 
2.12.1.382.gc0f9c7058