[Qemu-devel] [PATCH v3 0/3] Generic PCIe host bridge INTx determination for INTx routing

[Qemu-devel] [PATCH v3 0/3] Generic PCIe host bridge INTx determination for INTx routing

[Eric Auger]

This series implements INTx to gsi routing for ARM VIRT/GPEX. This is
a respin of [1] which was lost in limbo.

ARM virt uses GPEX PCIe bridge. This latter does not implement INTx
to GSI routing. PCIe/INTx assignment works but the consequence is
irqfd is not used along with INTx interrupts and VFIO INTx handlers
are executed on userspace leading to an important performance degradation.

This issue is witnessed by the following messages;

qemu-system-aarch64: -device vfio-pci,host=0006:90:00.0: PCI: Bug -
unimplemented PCI INTx routing (gpex-pcihost)
qemu-system-aarch64: PCI: Bug - unimplemented PCI INTx routing (gpex-pcihost)
qemu-system-aarch64: PCI: Bug - unimplemented PCI INTx routing (gpex-pcihost)

So with this series, irqfd is set up for PCIe/INTx passthrough and we get
the optimal performance. Also we get rid of the above messages.

This series can be found at:
https://github.com/eauger/qemu/tree/v2.9-gpex-intx-v3

References:
[1] Generic PCIe host bridge INTx determination for INTx routing
   https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg04975.html

Pranavkumar Sawargaonkar (3):
  hw/pci-host/gpex: Set INTx index/gsi mapping
  hw/arm/virt: Set INTx/gsi mapping
  hw/pci-host/gpex: Implement PCI INTx routing

 hw/arm/virt.c              |  4 ++++
 hw/pci-host/gpex.c         | 22 ++++++++++++++++++++++
 include/hw/pci-host/gpex.h |  3 +++
 3 files changed, 29 insertions(+)

-- 
2.5.5

[Qemu-devel] [PATCH v3 1/3] hw/pci-host/gpex: Set INTx index/gsi mapping

[Eric Auger]

From: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>

To implement INTx to gsi routing we need to pass the gpex host
bridge the gsi associated to each INTx index. Let's introduce
irq_num array and gpex_set_irq_num setter function.

Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Signed-off-by: Tushar Jagad <tushar.jagad@linaro.org>
Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
 hw/pci-host/gpex.c         | 10 ++++++++++
 include/hw/pci-host/gpex.h |  3 +++
 2 files changed, 13 insertions(+)

diff --git a/hw/pci-host/gpex.c b/hw/pci-host/gpex.c
index e2629ce..22367aa4 100644
--- a/hw/pci-host/gpex.c
+++ b/hw/pci-host/gpex.c
@@ -43,6 +43,16 @@ static void gpex_set_irq(void *opaque, int irq_num, int level)
     qemu_set_irq(s->irq[irq_num], level);
 }
 
+int gpex_set_irq_num(GPEXHost *s, int index, uint32_t gsi)
+{
+    if (index >=  GPEX_NUM_IRQS) {
+        return -EINVAL;
+    }
+
+    s->irq_num[index] = gsi;
+    return 0;
+}
+
 static void gpex_host_realize(DeviceState *dev, Error **errp)
 {
     PCIHostState *pci = PCI_HOST_BRIDGE(dev);
diff --git a/include/hw/pci-host/gpex.h b/include/hw/pci-host/gpex.h
index 68c9348..db26b3e 100644
--- a/include/hw/pci-host/gpex.h
+++ b/include/hw/pci-host/gpex.h
@@ -51,6 +51,9 @@ typedef struct GPEXHost {
     MemoryRegion io_ioport;
     MemoryRegion io_mmio;
     qemu_irq irq[GPEX_NUM_IRQS];
+    uint32_t irq_num[GPEX_NUM_IRQS];
 } GPEXHost;
 
+int gpex_set_irq_num(GPEXHost *s, int index, uint32_t gsi);
+
 #endif /* HW_GPEX_H */
-- 
2.5.5

[Qemu-devel] [PATCH v3 2/3] hw/arm/virt: Set INTx/gsi mapping

[Eric Auger]

From: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>

Let's provide the GPEX host bridge with the INTx/gsi mapping. This is
needed for INTx/gsi routing.

Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Signed-off-by: Tushar Jagad <tushar.jagad@linaro.org>
Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
 hw/arm/virt.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 010f724..f86c229 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1012,6 +1012,7 @@ static void create_pcie(const VirtMachineState *vms, qemu_irq *pic)
     char *nodename;
     int i;
     PCIHostState *pci;
+    GPEXHost *s;
 
     dev = qdev_create(NULL, TYPE_GPEX_HOST);
     qdev_init_nofail(dev);
@@ -1047,8 +1048,11 @@ static void create_pcie(const VirtMachineState *vms, qemu_irq *pic)
     /* Map IO port space */
     sysbus_mmio_map(SYS_BUS_DEVICE(dev), 2, base_pio);
 
+    s = GPEX_HOST(dev);
+
     for (i = 0; i < GPEX_NUM_IRQS; i++) {
         sysbus_connect_irq(SYS_BUS_DEVICE(dev), i, pic[irq + i]);
+        gpex_set_irq_num(s, i, irq + i);
     }
 
     pci = PCI_HOST_BRIDGE(dev);
-- 
2.5.5

[Qemu-devel] [PATCH v3 3/3] hw/pci-host/gpex: Implement PCI INTx routing

[Eric Auger]

From: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>

Now we are able to retrieve the gsi from the INTx pin, let's
enable intx_to_irq routing. From that point on, irqfd becomes
usable along with INTx when assigning a PCIe device.

Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Signed-off-by: Tushar Jagad <tushar.jagad@linaro.org>
Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
 hw/pci-host/gpex.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/hw/pci-host/gpex.c b/hw/pci-host/gpex.c
index 22367aa4..2ec918b 100644
--- a/hw/pci-host/gpex.c
+++ b/hw/pci-host/gpex.c
@@ -53,6 +53,17 @@ int gpex_set_irq_num(GPEXHost *s, int index, uint32_t gsi)
     return 0;
 }
 
+static PCIINTxRoute gpex_route_intx_pin_to_irq(void *opaque, int pin)
+{
+    PCIINTxRoute route;
+    GPEXHost *s = opaque;
+
+    route.mode = PCI_INTX_ENABLED;
+    route.irq = (int)s->irq_num[pin];
+
+    return route;
+}
+
 static void gpex_host_realize(DeviceState *dev, Error **errp)
 {
     PCIHostState *pci = PCI_HOST_BRIDGE(dev);
@@ -77,6 +88,7 @@ static void gpex_host_realize(DeviceState *dev, Error **errp)
                                 &s->io_ioport, 0, 4, TYPE_PCIE_BUS);
 
     qdev_set_parent_bus(DEVICE(&s->gpex_root), BUS(pci->bus));
+    pci_bus_set_route_irq_fn(pci->bus, gpex_route_intx_pin_to_irq);
     qdev_init_nofail(DEVICE(&s->gpex_root));
 }
 
-- 
2.5.5

Re: [Qemu-devel] [PATCH v3 0/3] Generic PCIe host bridge INTx determination for INTx routing

[Auger Eric]

Hi,

On 13/06/2017 15:31, Eric Auger wrote:
> This series implements INTx to gsi routing for ARM VIRT/GPEX. This is
> a respin of [1] which was lost in limbo.
> 
> ARM virt uses GPEX PCIe bridge. This latter does not implement INTx
> to GSI routing. PCIe/INTx assignment works but the consequence is
> irqfd is not used along with INTx interrupts and VFIO INTx handlers
> are executed on userspace leading to an important performance degradation.
> 
> This issue is witnessed by the following messages;
> 
> qemu-system-aarch64: -device vfio-pci,host=0006:90:00.0: PCI: Bug -
> unimplemented PCI INTx routing (gpex-pcihost)
> qemu-system-aarch64: PCI: Bug - unimplemented PCI INTx routing (gpex-pcihost)
> qemu-system-aarch64: PCI: Bug - unimplemented PCI INTx routing (gpex-pcihost)
> 
> So with this series, irqfd is set up for PCIe/INTx passthrough and we get
> the optimal performance. Also we get rid of the above messages.

Ping? any feedback on this series that fixes irqfd setup for PCIe
passthrough/ARM with legacy interrupts?

Thanks

Eric
> 
> This series can be found at:
> https://github.com/eauger/qemu/tree/v2.9-gpex-intx-v3
> 
> References:
> [1] Generic PCIe host bridge INTx determination for INTx routing
>    https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg04975.html
> 
> Pranavkumar Sawargaonkar (3):
>   hw/pci-host/gpex: Set INTx index/gsi mapping
>   hw/arm/virt: Set INTx/gsi mapping
>   hw/pci-host/gpex: Implement PCI INTx routing
> 
>  hw/arm/virt.c              |  4 ++++
>  hw/pci-host/gpex.c         | 22 ++++++++++++++++++++++
>  include/hw/pci-host/gpex.h |  3 +++
>  3 files changed, 29 insertions(+)
>