[PATCH 2/2] hw/usb: hcd-xhci-pci: Fix spec violation of IP flag for MSI/MSI-X

[Bin Meng]

From: Ruimei Yan <ruimei.yan@windriver.com>

Per xHCI spec v1.2 chapter 4.17.5 page 296:

  If MSI or MSI-X interrupts are enabled, Interrupt Pending (IP)
  shall be cleared automatically when the PCI dword write generated
  by the interrupt assertion is complete.

Currently QEMU does not clear the IP flag in the MSI / MSI-X mode.
This causes subsequent spurious interrupt to be delivered to guests.
To solve this, we change the xhci intr_raise() hook routine to have
a bool return value that is passed to its caller (the xhci core),
with true indicating that IP should be self-cleared.

Fixes: 62c6ae04cf43 ("xhci: Initial xHCI implementation")
Fixes: 4c47f800631a ("xhci: add msix support")
Signed-off-by: Ruimei Yan <ruimei.yan@windriver.com>
[bmeng: move IP clear codes from xhci pci to xhci core]
Signed-off-by: Bin Meng <bin.meng@windriver.com>
---

 hw/usb/hcd-xhci.h        | 2 +-
 hw/usb/hcd-xhci-pci.c    | 8 +++++---
 hw/usb/hcd-xhci-sysbus.c | 4 +++-
 hw/usb/hcd-xhci.c        | 8 ++++++--
 4 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/hw/usb/hcd-xhci.h b/hw/usb/hcd-xhci.h
index 7bba361f3b..98f598382a 100644
--- a/hw/usb/hcd-xhci.h
+++ b/hw/usb/hcd-xhci.h
@@ -194,7 +194,7 @@ typedef struct XHCIState {
     uint32_t flags;
     uint32_t max_pstreams_mask;
     void (*intr_update)(XHCIState *s, int n, bool enable);
-    void (*intr_raise)(XHCIState *s, int n, bool level);
+    bool (*intr_raise)(XHCIState *s, int n, bool level);
     DeviceState *hostOpaque;
 
     /* Operational Registers */
diff --git a/hw/usb/hcd-xhci-pci.c b/hw/usb/hcd-xhci-pci.c
index b6acd1790c..e934b1a5b1 100644
--- a/hw/usb/hcd-xhci-pci.c
+++ b/hw/usb/hcd-xhci-pci.c
@@ -57,7 +57,7 @@ static void xhci_pci_intr_update(XHCIState *xhci, int n, bool 
enable)
     }
 }
 
-static void xhci_pci_intr_raise(XHCIState *xhci, int n, bool level)
+static bool xhci_pci_intr_raise(XHCIState *xhci, int n, bool level)
 {
     XHCIPciState *s = container_of(xhci, XHCIPciState, xhci);
     PCIDevice *pci_dev = PCI_DEVICE(s);
@@ -70,13 +70,15 @@ static void xhci_pci_intr_raise(XHCIState *xhci, int n, 
bool level)
 
     if (msix_enabled(pci_dev) && level) {
         msix_notify(pci_dev, n);
-        return;
+        return true;
     }
 
     if (msi_enabled(pci_dev) && level) {
         msi_notify(pci_dev, n);
-        return;
+        return true;
     }
+
+    return false;
 }
 
 static void xhci_pci_reset(DeviceState *dev)
diff --git a/hw/usb/hcd-xhci-sysbus.c b/hw/usb/hcd-xhci-sysbus.c
index 42e2574c82..a14e438196 100644
--- a/hw/usb/hcd-xhci-sysbus.c
+++ b/hw/usb/hcd-xhci-sysbus.c
@@ -16,11 +16,13 @@
 #include "hw/acpi/aml-build.h"
 #include "hw/irq.h"
 
-static void xhci_sysbus_intr_raise(XHCIState *xhci, int n, bool level)
+static bool xhci_sysbus_intr_raise(XHCIState *xhci, int n, bool level)
 {
     XHCISysbusState *s = container_of(xhci, XHCISysbusState, xhci);
 
     qemu_set_irq(s->irq[n], level);
+
+    return false;
 }
 
 void xhci_sysbus_reset(DeviceState *dev)
diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c
index 46212b1e69..e01700039b 100644
--- a/hw/usb/hcd-xhci.c
+++ b/hw/usb/hcd-xhci.c
@@ -551,7 +551,9 @@ static void xhci_intr_update(XHCIState *xhci, int v)
             level = 1;
         }
         if (xhci->intr_raise) {
-            xhci->intr_raise(xhci, 0, level);
+            if (xhci->intr_raise(xhci, 0, level)) {
+                xhci->intr[0].iman &= ~IMAN_IP;
+            }
         }
     }
     if (xhci->intr_update) {
@@ -579,7 +581,9 @@ static void xhci_intr_raise(XHCIState *xhci, int v)
         return;
     }
     if (xhci->intr_raise) {
-        xhci->intr_raise(xhci, v, true);
+        if (xhci->intr_raise(xhci, v, true)) {
+            xhci->intr[v].iman &= ~IMAN_IP;
+        }
     }
 }
 
-- 
2.25.1