[PATCH] hw/pci: prevent hotplug of devices on pcie-root-ports with wrong devfn address

[PATCH] hw/pci: prevent hotplug of devices on pcie-root-ports with wrong devfn address

[Ani Sinha]

PCIE root ports only allow one device on slot 0/function 0. When hotplugging a
device on a pcie root port, make sure that the device address passed is
always 0x00 that represents slot 0 and function 0. Any other slot value and
function value would be illegal on a root port.

CC: jusual@redhat.com
CC: imammedo@redhat.com
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2128929
Signed-off-by: Ani Sinha <anisinha@redhat.com>
---
 hw/pci/pci.c | 9 +++++++++
 1 file changed, 9 insertions(+)

Note:
I tested this with both native and acpi hotplug enabled on pcie. The
check seems to work on both.

(qemu)  netdev_add socket,id=hostnet1,listen=:1234
(qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x2.0x5
Error: PCI: slot 2 function 5 is not valid for e1000e
(qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x0.0
(qemu) info network
net1: index=0,type=nic,model=e1000e,macaddr=00:11:22:33:44:03
 \ hostnet1: index=0,type=socket,
(qemu) device_del net1
(qemu) info network
hostnet1: index=0,type=socket,

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index bf38905b7d..bc39322dfd 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -64,6 +64,7 @@ bool pci_available = true;
 static char *pcibus_get_dev_path(DeviceState *dev);
 static char *pcibus_get_fw_dev_path(DeviceState *dev);
 static void pcibus_reset(BusState *qbus);
+static bool pcie_has_upstream_port(PCIDevice *dev);
 
 static Property pci_props[] = {
     DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
@@ -1189,6 +1190,14 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev,
                    name);
 
        return NULL;
+    } else if (dev->hotplugged &&
+               !pci_is_vf(pci_dev) &&
+               pcie_has_upstream_port(pci_dev) && devfn) {
+        /* For an upstream PCIE port, we only support one device at slot 0 */
+        error_setg(errp, "PCI: slot %d function %d is not valid for %s",
+                   PCI_SLOT(devfn), PCI_FUNC(devfn), name);
+        return NULL;
+
     }
 
     pci_dev->devfn = devfn;
-- 
2.39.1

Re: [PATCH] hw/pci: prevent hotplug of devices on pcie-root-ports with wrong devfn address

[Igor Mammedov]

On Wed, 14 Jun 2023 18:01:50 +0530
Ani Sinha <anisinha@redhat.com> wrote:

> PCIE root ports only allow one device on slot 0/function 0. When hotplugging a
> device on a pcie root port, make sure that the device address passed is
> always 0x00 that represents slot 0 and function 0. Any other slot value and
> function value would be illegal on a root port.
> 
> CC: jusual@redhat.com
> CC: imammedo@redhat.com
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2128929
> Signed-off-by: Ani Sinha <anisinha@redhat.com>
> ---
>  hw/pci/pci.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> Note:
> I tested this with both native and acpi hotplug enabled on pcie. The
> check seems to work on both.
> 
> (qemu)  netdev_add socket,id=hostnet1,listen=:1234
> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x2.0x5
> Error: PCI: slot 2 function 5 is not valid for e1000e
> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x0.0
> (qemu) info network
> net1: index=0,type=nic,model=e1000e,macaddr=00:11:22:33:44:03
>  \ hostnet1: index=0,type=socket,
> (qemu) device_del net1
> (qemu) info network
> hostnet1: index=0,type=socket,
> 
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index bf38905b7d..bc39322dfd 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -64,6 +64,7 @@ bool pci_available = true;
>  static char *pcibus_get_dev_path(DeviceState *dev);
>  static char *pcibus_get_fw_dev_path(DeviceState *dev);
>  static void pcibus_reset(BusState *qbus);
> +static bool pcie_has_upstream_port(PCIDevice *dev);
>  
>  static Property pci_props[] = {
>      DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
> @@ -1189,6 +1190,14 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev,
>                     name);
>  
>         return NULL;
> +    } else if (dev->hotplugged &&

> +               !pci_is_vf(pci_dev) &&
> +               pcie_has_upstream_port(pci_dev) 
can you clarify what above 2 lines are here for?

you can't hotplug anything into upstream port (only downstream)
and why _vf() is here also not clear.
 
> && devfn) {
> +        /* For an upstream PCIE port, we only support one device at slot 0 */
> +        error_setg(errp, "PCI: slot %d function %d is not valid for %s",
> +                   PCI_SLOT(devfn), PCI_FUNC(devfn), name);
> +        return NULL;
> +
>      }
>  
>      pci_dev->devfn = devfn;

Re: [PATCH] hw/pci: prevent hotplug of devices on pcie-root-ports with wrong devfn address

[Michael S. Tsirkin]

On Wed, Jun 14, 2023 at 06:01:50PM +0530, Ani Sinha wrote:
> PCIE root ports only allow one device on slot 0/function 0.


Why do you say this? PCI devices can be multifunction.

> When hotplugging a
> device on a pcie root port, make sure that the device address passed is
> always 0x00 that represents slot 0 and function 0. Any other slot value and
> function value would be illegal on a root port.
> 
> CC: jusual@redhat.com
> CC: imammedo@redhat.com
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2128929
> Signed-off-by: Ani Sinha <anisinha@redhat.com>
> ---
>  hw/pci/pci.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> Note:
> I tested this with both native and acpi hotplug enabled on pcie. The
> check seems to work on both.
> 
> (qemu)  netdev_add socket,id=hostnet1,listen=:1234
> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x2.0x5
> Error: PCI: slot 2 function 5 is not valid for e1000e
> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x0.0
> (qemu) info network
> net1: index=0,type=nic,model=e1000e,macaddr=00:11:22:33:44:03
>  \ hostnet1: index=0,type=socket,
> (qemu) device_del net1
> (qemu) info network
> hostnet1: index=0,type=socket,
> 
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index bf38905b7d..bc39322dfd 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -64,6 +64,7 @@ bool pci_available = true;
>  static char *pcibus_get_dev_path(DeviceState *dev);
>  static char *pcibus_get_fw_dev_path(DeviceState *dev);
>  static void pcibus_reset(BusState *qbus);
> +static bool pcie_has_upstream_port(PCIDevice *dev);
>  
>  static Property pci_props[] = {
>      DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
> @@ -1189,6 +1190,14 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev,
>                     name);
>  
>         return NULL;
> +    } else if (dev->hotplugged &&
> +               !pci_is_vf(pci_dev) &&
> +               pcie_has_upstream_port(pci_dev) && devfn) {
> +        /* For an upstream PCIE port, we only support one device at slot 0 */
> +        error_setg(errp, "PCI: slot %d function %d is not valid for %s",
> +                   PCI_SLOT(devfn), PCI_FUNC(devfn), name);
> +        return NULL;
> +
>      }
>  
>      pci_dev->devfn = devfn;
> -- 
> 2.39.1

Re: [PATCH] hw/pci: prevent hotplug of devices on pcie-root-ports with wrong devfn address

[Ani Sinha]

> On 14-Jun-2023, at 7:52 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
> 
> On Wed, Jun 14, 2023 at 06:01:50PM +0530, Ani Sinha wrote:
>> PCIE root ports only allow one device on slot 0/function 0.
> 
> 
> Why do you say this? PCI devices can be multifunction.

Yeah you are right, the language needs correction. For hot plugging, I believe only function 0 is relevant. At least that is what it looks like from the code.

> 
>> When hotplugging a
>> device on a pcie root port, make sure that the device address passed is
>> always 0x00 that represents slot 0 and function 0. Any other slot value and
>> function value would be illegal on a root port.
>> 
>> CC: jusual@redhat.com
>> CC: imammedo@redhat.com
>> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2128929
>> Signed-off-by: Ani Sinha <anisinha@redhat.com>
>> ---
>> hw/pci/pci.c | 9 +++++++++
>> 1 file changed, 9 insertions(+)
>> 
>> Note:
>> I tested this with both native and acpi hotplug enabled on pcie. The
>> check seems to work on both.
>> 
>> (qemu)  netdev_add socket,id=hostnet1,listen=:1234
>> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x2.0x5
>> Error: PCI: slot 2 function 5 is not valid for e1000e
>> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x0.0
>> (qemu) info network
>> net1: index=0,type=nic,model=e1000e,macaddr=00:11:22:33:44:03
>> \ hostnet1: index=0,type=socket,
>> (qemu) device_del net1
>> (qemu) info network
>> hostnet1: index=0,type=socket,
>> 
>> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
>> index bf38905b7d..bc39322dfd 100644
>> --- a/hw/pci/pci.c
>> +++ b/hw/pci/pci.c
>> @@ -64,6 +64,7 @@ bool pci_available = true;
>> static char *pcibus_get_dev_path(DeviceState *dev);
>> static char *pcibus_get_fw_dev_path(DeviceState *dev);
>> static void pcibus_reset(BusState *qbus);
>> +static bool pcie_has_upstream_port(PCIDevice *dev);
>> 
>> static Property pci_props[] = {
>>     DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
>> @@ -1189,6 +1190,14 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev,
>>                    name);
>> 
>>        return NULL;
>> +    } else if (dev->hotplugged &&
>> +               !pci_is_vf(pci_dev) &&
>> +               pcie_has_upstream_port(pci_dev) && devfn) {
>> +        /* For an upstream PCIE port, we only support one device at slot 0 */
>> +        error_setg(errp, "PCI: slot %d function %d is not valid for %s",
>> +                   PCI_SLOT(devfn), PCI_FUNC(devfn), name);
>> +        return NULL;
>> +
>>     }
>> 
>>     pci_dev->devfn = devfn;
>> -- 
>> 2.39.1
> 

Re: [PATCH] hw/pci: prevent hotplug of devices on pcie-root-ports with wrong devfn address

[Ani Sinha]

> On 14-Jun-2023, at 6:31 PM, Igor Mammedov <imammedo@redhat.com> wrote:
> 
> On Wed, 14 Jun 2023 18:01:50 +0530
> Ani Sinha <anisinha@redhat.com> wrote:
> 
>> PCIE root ports only allow one device on slot 0/function 0. When hotplugging a
>> device on a pcie root port, make sure that the device address passed is
>> always 0x00 that represents slot 0 and function 0. Any other slot value and
>> function value would be illegal on a root port.
>> 
>> CC: jusual@redhat.com
>> CC: imammedo@redhat.com
>> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2128929
>> Signed-off-by: Ani Sinha <anisinha@redhat.com>
>> ---
>> hw/pci/pci.c | 9 +++++++++
>> 1 file changed, 9 insertions(+)
>> 
>> Note:
>> I tested this with both native and acpi hotplug enabled on pcie. The
>> check seems to work on both.
>> 
>> (qemu)  netdev_add socket,id=hostnet1,listen=:1234
>> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x2.0x5
>> Error: PCI: slot 2 function 5 is not valid for e1000e
>> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x0.0
>> (qemu) info network
>> net1: index=0,type=nic,model=e1000e,macaddr=00:11:22:33:44:03
>> \ hostnet1: index=0,type=socket,
>> (qemu) device_del net1
>> (qemu) info network
>> hostnet1: index=0,type=socket,
>> 
>> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
>> index bf38905b7d..bc39322dfd 100644
>> --- a/hw/pci/pci.c
>> +++ b/hw/pci/pci.c
>> @@ -64,6 +64,7 @@ bool pci_available = true;
>> static char *pcibus_get_dev_path(DeviceState *dev);
>> static char *pcibus_get_fw_dev_path(DeviceState *dev);
>> static void pcibus_reset(BusState *qbus);
>> +static bool pcie_has_upstream_port(PCIDevice *dev);
>> 
>> static Property pci_props[] = {
>>     DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
>> @@ -1189,6 +1190,14 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev,
>>                    name);
>> 
>>        return NULL;
>> +    } else if (dev->hotplugged &&
> 
>> +               !pci_is_vf(pci_dev) &&
>> +               pcie_has_upstream_port(pci_dev) 
> can you clarify what above 2 lines are here for?
> 
> you can't hotplug anything into upstream port (only downstream)

This code checks if the hot plugged device is being plugged into a pcie root port. For pcie root ports, only slot 0 can be used. Please see 3f1e1478db2d67098d9 . The conditional check just above this hunk therefore checks for unoccupied function 0 in slot 0 if the device is plugged into an upstream pcie root port. I think for hot plugs, only function 0 is allowed.

As for vf, I am not sure. I believe for vfs the restriction is not valid. I just kept the check based on the conditional just prior to it.

> and why _vf() is here also not clear.
> 
>> && devfn) {
>> +        /* For an upstream PCIE port, we only support one device at slot 0 */
>> +        error_setg(errp, "PCI: slot %d function %d is not valid for %s",
>> +                   PCI_SLOT(devfn), PCI_FUNC(devfn), name);
>> +        return NULL;
>> +
>>     }
>> 
>>     pci_dev->devfn = devfn;

Re: [PATCH] hw/pci: prevent hotplug of devices on pcie-root-ports with wrong devfn address

[Michael S. Tsirkin]

On Wed, Jun 14, 2023 at 10:31:40PM +0530, Ani Sinha wrote:
> 
> 
> > On 14-Jun-2023, at 6:31 PM, Igor Mammedov <imammedo@redhat.com> wrote:
> > 
> > On Wed, 14 Jun 2023 18:01:50 +0530
> > Ani Sinha <anisinha@redhat.com> wrote:
> > 
> >> PCIE root ports only allow one device on slot 0/function 0. When hotplugging a
> >> device on a pcie root port, make sure that the device address passed is
> >> always 0x00 that represents slot 0 and function 0. Any other slot value and
> >> function value would be illegal on a root port.
> >> 
> >> CC: jusual@redhat.com
> >> CC: imammedo@redhat.com
> >> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2128929
> >> Signed-off-by: Ani Sinha <anisinha@redhat.com>
> >> ---
> >> hw/pci/pci.c | 9 +++++++++
> >> 1 file changed, 9 insertions(+)
> >> 
> >> Note:
> >> I tested this with both native and acpi hotplug enabled on pcie. The
> >> check seems to work on both.
> >> 
> >> (qemu)  netdev_add socket,id=hostnet1,listen=:1234
> >> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x2.0x5
> >> Error: PCI: slot 2 function 5 is not valid for e1000e
> >> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x0.0
> >> (qemu) info network
> >> net1: index=0,type=nic,model=e1000e,macaddr=00:11:22:33:44:03
> >> \ hostnet1: index=0,type=socket,
> >> (qemu) device_del net1
> >> (qemu) info network
> >> hostnet1: index=0,type=socket,
> >> 
> >> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> >> index bf38905b7d..bc39322dfd 100644
> >> --- a/hw/pci/pci.c
> >> +++ b/hw/pci/pci.c
> >> @@ -64,6 +64,7 @@ bool pci_available = true;
> >> static char *pcibus_get_dev_path(DeviceState *dev);
> >> static char *pcibus_get_fw_dev_path(DeviceState *dev);
> >> static void pcibus_reset(BusState *qbus);
> >> +static bool pcie_has_upstream_port(PCIDevice *dev);
> >> 
> >> static Property pci_props[] = {
> >>     DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
> >> @@ -1189,6 +1190,14 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev,
> >>                    name);
> >> 
> >>        return NULL;
> >> +    } else if (dev->hotplugged &&
> > 
> >> +               !pci_is_vf(pci_dev) &&
> >> +               pcie_has_upstream_port(pci_dev) 
> > can you clarify what above 2 lines are here for?
> > 
> > you can't hotplug anything into upstream port (only downstream)
> 
> This code checks if the hot plugged device is being plugged into a pcie root port. For pcie root ports, only slot 0 can be used. Please see 3f1e1478db2d67098d9 . The conditional check just above this hunk therefore checks for unoccupied function 0 in slot 0 if the device is plugged into an upstream pcie root port. I think for hot plugs, only function 0 is allowed.

Not really. The way we hotplug a multifunction device is by first
populating all functions != 0, then finally pupulating function 0
which is when the event triggers.

> 
> As for vf, I am not sure. I believe for vfs the restriction is not valid. I just kept the check based on the conditional just prior to it.
> 
> > and why _vf() is here also not clear.
> > 
> >> && devfn) {
> >> +        /* For an upstream PCIE port, we only support one device at slot 0 */
> >> +        error_setg(errp, "PCI: slot %d function %d is not valid for %s",
> >> +                   PCI_SLOT(devfn), PCI_FUNC(devfn), name);
> >> +        return NULL;
> >> +
> >>     }
> >> 
> >>     pci_dev->devfn = devfn;

Re: [PATCH] hw/pci: prevent hotplug of devices on pcie-root-ports with wrong devfn address

[Michael S. Tsirkin]

On Wed, Jun 14, 2023 at 10:09:35PM +0530, Ani Sinha wrote:
> 
> 
> > On 14-Jun-2023, at 7:52 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
> > 
> > On Wed, Jun 14, 2023 at 06:01:50PM +0530, Ani Sinha wrote:
> >> PCIE root ports only allow one device on slot 0/function 0.
> > 
> > 
> > Why do you say this? PCI devices can be multifunction.
> 
> Yeah you are right, the language needs correction. For hot plugging, I believe only function 0 is relevant. At least that is what it looks like from the code.

Adding function 0 is what makes it visible to guest.
But you can't block multifunction devices that would be a regression.


> > 
> >> When hotplugging a
> >> device on a pcie root port, make sure that the device address passed is
> >> always 0x00 that represents slot 0 and function 0. Any other slot value and
> >> function value would be illegal on a root port.
> >> 
> >> CC: jusual@redhat.com
> >> CC: imammedo@redhat.com
> >> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2128929
> >> Signed-off-by: Ani Sinha <anisinha@redhat.com>
> >> ---
> >> hw/pci/pci.c | 9 +++++++++
> >> 1 file changed, 9 insertions(+)
> >> 
> >> Note:
> >> I tested this with both native and acpi hotplug enabled on pcie. The
> >> check seems to work on both.
> >> 
> >> (qemu)  netdev_add socket,id=hostnet1,listen=:1234
> >> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x2.0x5
> >> Error: PCI: slot 2 function 5 is not valid for e1000e
> >> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x0.0
> >> (qemu) info network
> >> net1: index=0,type=nic,model=e1000e,macaddr=00:11:22:33:44:03
> >> \ hostnet1: index=0,type=socket,
> >> (qemu) device_del net1
> >> (qemu) info network
> >> hostnet1: index=0,type=socket,
> >> 
> >> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> >> index bf38905b7d..bc39322dfd 100644
> >> --- a/hw/pci/pci.c
> >> +++ b/hw/pci/pci.c
> >> @@ -64,6 +64,7 @@ bool pci_available = true;
> >> static char *pcibus_get_dev_path(DeviceState *dev);
> >> static char *pcibus_get_fw_dev_path(DeviceState *dev);
> >> static void pcibus_reset(BusState *qbus);
> >> +static bool pcie_has_upstream_port(PCIDevice *dev);
> >> 
> >> static Property pci_props[] = {
> >>     DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
> >> @@ -1189,6 +1190,14 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev,
> >>                    name);
> >> 
> >>        return NULL;
> >> +    } else if (dev->hotplugged &&
> >> +               !pci_is_vf(pci_dev) &&
> >> +               pcie_has_upstream_port(pci_dev) && devfn) {
> >> +        /* For an upstream PCIE port, we only support one device at slot 0 */
> >> +        error_setg(errp, "PCI: slot %d function %d is not valid for %s",
> >> +                   PCI_SLOT(devfn), PCI_FUNC(devfn), name);
> >> +        return NULL;
> >> +
> >>     }
> >> 
> >>     pci_dev->devfn = devfn;
> >> -- 
> >> 2.39.1
> > 

Re: [PATCH] hw/pci: prevent hotplug of devices on pcie-root-ports with wrong devfn address

[Ani Sinha]

> On 15-Jun-2023, at 2:22 AM, Michael S. Tsirkin <mst@redhat.com> wrote:
> 
> On Wed, Jun 14, 2023 at 10:31:40PM +0530, Ani Sinha wrote:
>> 
>> 
>>> On 14-Jun-2023, at 6:31 PM, Igor Mammedov <imammedo@redhat.com> wrote:
>>> 
>>> On Wed, 14 Jun 2023 18:01:50 +0530
>>> Ani Sinha <anisinha@redhat.com> wrote:
>>> 
>>>> PCIE root ports only allow one device on slot 0/function 0. When hotplugging a
>>>> device on a pcie root port, make sure that the device address passed is
>>>> always 0x00 that represents slot 0 and function 0. Any other slot value and
>>>> function value would be illegal on a root port.
>>>> 
>>>> CC: jusual@redhat.com
>>>> CC: imammedo@redhat.com
>>>> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2128929
>>>> Signed-off-by: Ani Sinha <anisinha@redhat.com>
>>>> ---
>>>> hw/pci/pci.c | 9 +++++++++
>>>> 1 file changed, 9 insertions(+)
>>>> 
>>>> Note:
>>>> I tested this with both native and acpi hotplug enabled on pcie. The
>>>> check seems to work on both.
>>>> 
>>>> (qemu)  netdev_add socket,id=hostnet1,listen=:1234
>>>> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x2.0x5
>>>> Error: PCI: slot 2 function 5 is not valid for e1000e
>>>> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x0.0
>>>> (qemu) info network
>>>> net1: index=0,type=nic,model=e1000e,macaddr=00:11:22:33:44:03
>>>> \ hostnet1: index=0,type=socket,
>>>> (qemu) device_del net1
>>>> (qemu) info network
>>>> hostnet1: index=0,type=socket,
>>>> 
>>>> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
>>>> index bf38905b7d..bc39322dfd 100644
>>>> --- a/hw/pci/pci.c
>>>> +++ b/hw/pci/pci.c
>>>> @@ -64,6 +64,7 @@ bool pci_available = true;
>>>> static char *pcibus_get_dev_path(DeviceState *dev);
>>>> static char *pcibus_get_fw_dev_path(DeviceState *dev);
>>>> static void pcibus_reset(BusState *qbus);
>>>> +static bool pcie_has_upstream_port(PCIDevice *dev);
>>>> 
>>>> static Property pci_props[] = {
>>>>    DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
>>>> @@ -1189,6 +1190,14 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev,
>>>>                   name);
>>>> 
>>>>       return NULL;
>>>> +    } else if (dev->hotplugged &&
>>> 
>>>> +               !pci_is_vf(pci_dev) &&
>>>> +               pcie_has_upstream_port(pci_dev) 
>>> can you clarify what above 2 lines are here for?
>>> 
>>> you can't hotplug anything into upstream port (only downstream)
>> 
>> This code checks if the hot plugged device is being plugged into a pcie root port. For pcie root ports, only slot 0 can be used. Please see 3f1e1478db2d67098d9 . The conditional check just above this hunk therefore checks for unoccupied function 0 in slot 0 if the device is plugged into an upstream pcie root port. I think for hot plugs, only function 0 is allowed.
> 
> Not really. The way we hotplug a multifunction device is by first
> populating all functions != 0, then finally pupulating function 0
> which is when the event triggers.

Let me explain better ..

This check currently already exists:
    } else if (dev->hotplugged &&
               !pci_is_vf(pci_dev) &&
               pci_get_function_0(pci_dev)) {
        error_setg(errp, "PCI: slot %d function 0 already occupied by %s,"
                   " new func %s cannot be exposed to guest.",
                   PCI_SLOT(pci_get_function_0(pci_dev)->devfn),
                   pci_get_function_0(pci_dev)->name,
                   name);

       return NULL;
    }

This code checks for unoccupied function 0. If you look into pci_get_function_0(), it checks for slot 0 function 0 for devices that are plugged into pcie root port.

> 
>> 
>> As for vf, I am not sure. I believe for vfs the restriction is not valid. I just kept the check based on the conditional just prior to it.
>> 
>>> and why _vf() is here also not clear.
>>> 
>>>> && devfn) {
>>>> +        /* For an upstream PCIE port, we only support one device at slot 0 */
>>>> +        error_setg(errp, "PCI: slot %d function %d is not valid for %s",
>>>> +                   PCI_SLOT(devfn), PCI_FUNC(devfn), name);
>>>> +        return NULL;
>>>> +
>>>>    }
>>>> 
>>>>    pci_dev->devfn = devfn;

Re: [PATCH] hw/pci: prevent hotplug of devices on pcie-root-ports with wrong devfn address

[Ani Sinha]

> On 15-Jun-2023, at 2:23 AM, Michael S. Tsirkin <mst@redhat.com> wrote:
> 
> On Wed, Jun 14, 2023 at 10:09:35PM +0530, Ani Sinha wrote:
>> 
>> 
>>> On 14-Jun-2023, at 7:52 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
>>> 
>>> On Wed, Jun 14, 2023 at 06:01:50PM +0530, Ani Sinha wrote:
>>>> PCIE root ports only allow one device on slot 0/function 0.
>>> 
>>> 
>>> Why do you say this? PCI devices can be multifunction.
>> 
>> Yeah you are right, the language needs correction. For hot plugging, I believe only function 0 is relevant. At least that is what it looks like from the code.
> 
> Adding function 0 is what makes it visible to guest.
> But you can't block multifunction devices that would be a regression.

OK fair enough and I can make a small adjustment in the code.

> 
> 
>>> 
>>>> When hotplugging a
>>>> device on a pcie root port, make sure that the device address passed is
>>>> always 0x00 that represents slot 0 and function 0. Any other slot value and
>>>> function value would be illegal on a root port.
>>>> 
>>>> CC: jusual@redhat.com
>>>> CC: imammedo@redhat.com
>>>> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2128929
>>>> Signed-off-by: Ani Sinha <anisinha@redhat.com>
>>>> ---
>>>> hw/pci/pci.c | 9 +++++++++
>>>> 1 file changed, 9 insertions(+)
>>>> 
>>>> Note:
>>>> I tested this with both native and acpi hotplug enabled on pcie. The
>>>> check seems to work on both.
>>>> 
>>>> (qemu)  netdev_add socket,id=hostnet1,listen=:1234
>>>> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x2.0x5
>>>> Error: PCI: slot 2 function 5 is not valid for e1000e
>>>> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x0.0
>>>> (qemu) info network
>>>> net1: index=0,type=nic,model=e1000e,macaddr=00:11:22:33:44:03
>>>> \ hostnet1: index=0,type=socket,
>>>> (qemu) device_del net1
>>>> (qemu) info network
>>>> hostnet1: index=0,type=socket,
>>>> 
>>>> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
>>>> index bf38905b7d..bc39322dfd 100644
>>>> --- a/hw/pci/pci.c
>>>> +++ b/hw/pci/pci.c
>>>> @@ -64,6 +64,7 @@ bool pci_available = true;
>>>> static char *pcibus_get_dev_path(DeviceState *dev);
>>>> static char *pcibus_get_fw_dev_path(DeviceState *dev);
>>>> static void pcibus_reset(BusState *qbus);
>>>> +static bool pcie_has_upstream_port(PCIDevice *dev);
>>>> 
>>>> static Property pci_props[] = {
>>>>    DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
>>>> @@ -1189,6 +1190,14 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev,
>>>>                   name);
>>>> 
>>>>       return NULL;
>>>> +    } else if (dev->hotplugged &&
>>>> +               !pci_is_vf(pci_dev) &&
>>>> +               pcie_has_upstream_port(pci_dev) && devfn) {
>>>> +        /* For an upstream PCIE port, we only support one device at slot 0 */
>>>> +        error_setg(errp, "PCI: slot %d function %d is not valid for %s",
>>>> +                   PCI_SLOT(devfn), PCI_FUNC(devfn), name);
>>>> +        return NULL;
>>>> +
>>>>    }
>>>> 
>>>>    pci_dev->devfn = devfn;
>>>> -- 
>>>> 2.39.1
>>> 
>