From 639e4c3be0cc6d92b75d9267fe40645d5f515b47 Mon Sep 17 00:00:00 2001

From: Laszlo Ersek <lersek@redhat.com>

Date: Thu, 10 Jul 2014 13:54:30 +0200

Subject: uhci: UNfix irq routing for RHEL-6 machtypes (RHEL only)

Message-id: <1405000470-9229-2-git-send-email-lersek@redhat.com>

Patchwork-id: 59740

O-Subject: [RHEV-7.1 qemu-kvm-rhev PATCH 1/1] uhci: UNfix irq routing for RHEL-6 machtypes (RHEL only)

Bugzilla: 1103581

RH-Acked-by: Gerd Hoffmann <kraxel@redhat.com>

RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>

RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

RH-Author: Laszlo Ersek <lersek@redhat.com>

Message-id: <1398337043-4967-1-git-send-email-lersek@redhat.com>

Patchwork-id: 58540

O-Subject: [RHEL-7.0 0day qemu-kvm PATCH] uhci: UNfix irq routing for RHEL-6 machtypes (RHEL only)

Bugzilla: 1085701

RH-Acked-by: Gerd Hoffmann <kraxel@redhat.com>

RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>

RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1085701

Brew:     https://brewweb.devel.redhat.com/taskinfo?taskID=7368968

Tested by myself and QE.

(Note that the bulk of the work related to this issue happened in bug

1027565 comments 64 to 74, because QE was experiencing it with the other

(original) issue reported in bug 1027565. Only later did I realize that

bug 1085701 already existed for this specific problem.)

Refer to the following upstream commit, present in v1.2.0 and RHEL-7:

    commit 973002c11460efd3c17fe61a76711a103e30e1f9

    Author: Gerd Hoffmann <kraxel@redhat.com>

    Date:   Fri May 25 12:53:47 2012 +0200

        uhci: fix irq routing

        The multifunction ich9 ehci controller with uhci companions uses a

        different interrupt pin for each function.  The three uhci devices

        get pins A, B and C, whereas ehci uses pin D.  This way the guest

        can assign different IRQ lines to each controller.

        Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

This is a performance optimization so that IRQ sharing can be avoided in

the guest.

Contrarily, the RHEL-6 emulator exclusively assigns pin D to each of the

three devices (see "hw/usb-uhci.c" there):

- usb_uhci_ich9_1_initfn()

- usb_uhci_ich9_2_initfn()

- usb_uhci_ich9_3_initfn()

These init functions call usb_uhci_common_initfn(), which in turn assigns:

    pci_conf[0x3d] = 4; // interrupt pin 3

This mismatch breaks migration for rhel6.x.0 machine types from the

RHEL-6.5 emulator to the RHEL-7.0 one.

For example, considering the uhci1 controller, the guest kernel, started

on the RHEL-6.5 source host, will see pin D advertised, and (according to

the PCI interrupt routing table provided by SeaBIOS) will route it to IRQ

11:

  dmesg:

    uhci_hcd 0000:00:11.0: PCI INT D -> Link[LNKD] -> GSI 11 (level, high)

    -> IRQ 11

  /proc/interrupts:

     10: ... IO-APIC-fasteoi   virtio0

     11: ... IO-APIC-fasteoi   uhci_hcd:usb1

When the same guest kernel, using the same rhel6.5.0 machine type, is

started fresh on the RHEL-7.0 target host, pin A is advertised instead

(and routed to a different IRQ, based on the same table from SeaBIOS):

  dmesg:

    uhci_hcd 0000:00:11.0: PCI INT A -> Link[LNKA] -> GSI 10 (level, high)

    -> IRQ 10

  /proc/interrupts:

     10: ... IO-APIC-fasteoi   uhci_hcd:usb1, virtio0

This is no problem as long as we don't migrate.

When we migrate the rhel6.x.0 machtype guest from the RHEL-6.5 host to the

RHEL-7.0 host, the guest kernel (having booted on the source host) will

expect the interrupts for the UHCI device on pin D / IRQ 11. However, the

target host will inject the interrupts on pin A / IRQ 10. No handler in

the guest kernel will claim such IRQ 10 instances (examples are: HDA or

virtio-balloon), hence IRQ 10 will be disabled.

We can fix this in at least two ways:

(1) Drop the persistent "UHCIState.irq_pin" field, and simply use the pin

    identifier that is stored in (already migrated) PCI config space (at

    offset 0x3d).

(2) Introduce yet another RHEL-6 compatibility knob that selects pin D for

    all three ICH9-UHCI controllers.

Since PCI config space could be write-accessible to the guest, plus it

could originate from an untrusted migration source as well, and we'd use

the setting as a subscript into the s->dev.irq[] array in

uhci_update_irq(), it seems safer to go with (2).

Signed-off-by: Laszlo Ersek <lersek@redhat.com>

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c

index 021cf22..1393ca1 100644

--- a/hw/i386/pc_piix.c

+++ b/hw/i386/pc_piix.c

@@ -1157,6 +1157,7 @@ static void pc_compat_rhel650(MachineState *machine)

     has_acpi_build = false;

     gigabyte_align = false;

     shadow_bios_after_incoming = true;

+    ich9_uhci123_irqpin_override = true;

 }

 static void pc_init_rhel650(MachineState *machine)

diff --git a/hw/usb/hcd-uhci.c b/hw/usb/hcd-uhci.c

index c3bf72c..61f3578 100644

--- a/hw/usb/hcd-uhci.c

+++ b/hw/usb/hcd-uhci.c

@@ -153,6 +153,8 @@ typedef struct UHCI_QH {

     uint32_t el_link;

 } UHCI_QH;

+bool ich9_uhci123_irqpin_override;

+

 static void uhci_async_cancel(UHCIAsync *async);

 static void uhci_queue_fill(UHCIQueue *q, UHCI_TD *td);

 static void uhci_resume(void *opaque);

@@ -1200,12 +1202,23 @@ static int usb_uhci_common_initfn(PCIDevice *dev)

     UHCIState *s = DO_UPCAST(UHCIState, dev, dev);

     uint8_t *pci_conf = s->dev.config;

     int i;

+    int irq_pin;

     pci_conf[PCI_CLASS_PROG] = 0x00;

     /* TODO: reset value should be 0. */

     pci_conf[USB_SBRN] = USB_RELEASE_1; // release number

-    pci_config_set_interrupt_pin(pci_conf, u->info.irq_pin + 1);

+    if (ich9_uhci123_irqpin_override &&

+        u->info.vendor_id == PCI_VENDOR_ID_INTEL &&

+        (u->info.device_id == PCI_DEVICE_ID_INTEL_82801I_UHCI1 ||

+         u->info.device_id == PCI_DEVICE_ID_INTEL_82801I_UHCI2 ||

+         u->info.device_id == PCI_DEVICE_ID_INTEL_82801I_UHCI3)) {

+        fprintf(stderr, "RHEL-6 compat: %s: irq_pin = 3\n", u->info.name);

+        irq_pin = 3;

+    } else {

+        irq_pin = u->info.irq_pin;

+    }

+    pci_config_set_interrupt_pin(pci_conf, irq_pin + 1);

     if (s->masterbus) {

         USBPort *ports[NB_PORTS];

diff --git a/include/hw/usb.h b/include/hw/usb.h

index 8bcab48..fad90bf 100644

--- a/include/hw/usb.h

+++ b/include/hw/usb.h

@@ -600,4 +600,8 @@ int usb_get_quirks(uint16_t vendor_id, uint16_t product_id,

                    uint8_t interface_class, uint8_t interface_subclass,

                    uint8_t interface_protocol);

+

+/* hcd-uhci.c -- RHEL-6 machine type compatibility */

+extern bool ich9_uhci123_irqpin_override;

+

 #endif