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* [PATCH v2] acpi: x86: pcihp: add support hotplug on multifunction bridges
@ 2021-07-23  9:04 Igor Mammedov
  2021-07-25  8:11 ` Marcel Apfelbaum
  0 siblings, 1 reply; 2+ messages in thread
From: Igor Mammedov @ 2021-07-23  9:04 UTC (permalink / raw)
  To: qemu-devel; +Cc: Laurent Vivier, peter.maydell, berrange, mst, jusual

Commit [1] switched PCI hotplug from native to ACPI one by default.

That however breaks hotplug on following CLI that used to work:
   -nodefaults -machine q35 \
   -device pcie-root-port,id=pcie-root-port-0,multifunction=on,bus=pcie.0,addr=0x1,chassis=1 \
   -device pcie-root-port,id=pcie-root-port-1,port=0x1,addr=0x1.0x1,bus=pcie.0,chassis=2

where PCI device is hotplugged to pcie-root-port-1 with error on guest side:

  ACPI BIOS Error (bug): Could not resolve symbol [^S0B.PCNT], AE_NOT_FOUND (20201113/psargs-330)
  ACPI Error: Aborting method \_SB.PCI0.PCNT due to previous error (AE_NOT_FOUND) (20201113/psparse-531)
  ACPI Error: Aborting method \_GPE._E01 due to previous error (AE_NOT_FOUND) (20201113/psparse-531)
  ACPI Error: AE_NOT_FOUND, while evaluating GPE method [_E01] (20201113/evgpe-515)

cause is that QEMU's ACPI hotplug never supported functions other then 0
and due to bug it was generating notification entries for not described
functions.

Technically there is no reason not to describe cold-plugged bridges
(root ports) on functions other then 0, as they similarly to bridge
on function 0 are unpluggable.

So since we need to describe multifunction devices iterate over
fuctions as well. But describe only cold-plugged bridges[root ports]
on functions other than 0 as well.

1)
Fixes: 17858a169508609ca9063c544833e5a1adeb7b52 (hw/acpi/ich9: Set ACPI PCI hot-plug as default on Q35)
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reported-by: Laurent Vivier <lvivier@redhat.com>
---
v2:
  * squash 1/2 "acpi: x86: pcihp: cleanup devfn usage in  build_append_pci_bus_devices()"
    into the main patch
  * drop Sxx -> Sxxx change as devfn fits into 2 digits anyway
  * cleanup PCI_FUN/DEVFN and use func/devfn local variables instead
  * fix typos
---
 hw/i386/acpi-build.c | 44 ++++++++++++++++++++++++++++++--------------
 1 file changed, 30 insertions(+), 14 deletions(-)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 17836149fe..a33ac8b91e 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -374,7 +374,7 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,
     Aml *dev, *notify_method = NULL, *method;
     QObject *bsel;
     PCIBus *sec;
-    int i;
+    int devfn;
 
     bsel = object_property_get_qobject(OBJECT(bus), ACPI_PCIHP_PROP_BSEL, NULL);
     if (bsel) {
@@ -384,23 +384,31 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,
         notify_method = aml_method("DVNT", 2, AML_NOTSERIALIZED);
     }
 
-    for (i = 0; i < ARRAY_SIZE(bus->devices); i += PCI_FUNC_MAX) {
+    for (devfn = 0; devfn < ARRAY_SIZE(bus->devices); devfn++) {
         DeviceClass *dc;
         PCIDeviceClass *pc;
-        PCIDevice *pdev = bus->devices[i];
-        int slot = PCI_SLOT(i);
+        PCIDevice *pdev = bus->devices[devfn];
+        int slot = PCI_SLOT(devfn);
+        int func = PCI_FUNC(devfn);
+        /* ACPI spec: 1.0b: Table 6-2 _ADR Object Bus Types, PCI type */
+        int adr = slot << 16 | func;
         bool hotplug_enabled_dev;
         bool bridge_in_acpi;
         bool cold_plugged_bridge;
 
         if (!pdev) {
-            if (bsel) { /* add hotplug slots for non present devices */
+            /*
+             * add hotplug slots for non present devices.
+             * hotplug is supported only for non-multifunction device
+             * so generate device description only for function 0
+             */
+            if (bsel && !func) {
                 if (pci_bus_is_express(bus) && slot > 0) {
                     break;
                 }
-                dev = aml_device("S%.02X", PCI_DEVFN(slot, 0));
+                dev = aml_device("S%.02X", devfn);
                 aml_append(dev, aml_name_decl("_SUN", aml_int(slot)));
-                aml_append(dev, aml_name_decl("_ADR", aml_int(slot << 16)));
+                aml_append(dev, aml_name_decl("_ADR", aml_int(adr)));
                 method = aml_method("_EJ0", 1, AML_NOTSERIALIZED);
                 aml_append(method,
                     aml_call2("PCEJ", aml_name("BSEL"), aml_name("_SUN"))
@@ -436,9 +444,18 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,
             continue;
         }
 
-        /* start to compose PCI slot descriptor */
-        dev = aml_device("S%.02X", PCI_DEVFN(slot, 0));
-        aml_append(dev, aml_name_decl("_ADR", aml_int(slot << 16)));
+        /*
+         * allow describing coldplugged bridges in ACPI even if they are not
+         * on function 0, as they are not unpluggable, for all other devices
+         * generate description only for function 0 per slot
+         */
+        if (func && !bridge_in_acpi) {
+            continue;
+        }
+
+        /* start to compose PCI device descriptor */
+        dev = aml_device("S%.02X", devfn);
+        aml_append(dev, aml_name_decl("_ADR", aml_int(adr)));
 
         if (bsel) {
             /*
@@ -496,7 +513,7 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,
 
             build_append_pci_bus_devices(dev, sec_bus, pcihp_bridge_en);
         }
-        /* slot descriptor has been composed, add it into parent context */
+        /* device descriptor has been composed, add it into parent context */
         aml_append(parent_scope, dev);
     }
 
@@ -525,13 +542,12 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,
         /* Notify about child bus events in any case */
         if (pcihp_bridge_en) {
             QLIST_FOREACH(sec, &bus->child, sibling) {
-                int32_t devfn = sec->parent_dev->devfn;
-
                 if (pci_bus_is_root(sec)) {
                     continue;
                 }
 
-                aml_append(method, aml_name("^S%.02X.PCNT", devfn));
+                aml_append(method, aml_name("^S%.02X.PCNT",
+                                            sec->parent_dev->devfn));
             }
         }
 
-- 
2.27.0



^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH v2] acpi: x86: pcihp: add support hotplug on multifunction bridges
  2021-07-23  9:04 [PATCH v2] acpi: x86: pcihp: add support hotplug on multifunction bridges Igor Mammedov
@ 2021-07-25  8:11 ` Marcel Apfelbaum
  0 siblings, 0 replies; 2+ messages in thread
From: Marcel Apfelbaum @ 2021-07-25  8:11 UTC (permalink / raw)
  To: Igor Mammedov
  Cc: Laurent Vivier, Peter Maydell, Daniel P. Berrangé,
	Michael S. Tsirkin, Julia Suvorova, qemu devel list

[-- Attachment #1: Type: text/plain, Size: 6459 bytes --]

Hi Igor,

On Fri, Jul 23, 2021 at 12:04 PM Igor Mammedov <imammedo@redhat.com> wrote:

> Commit [1] switched PCI hotplug from native to ACPI one by default.
>
> That however breaks hotplug on following CLI that used to work:
>    -nodefaults -machine q35 \
>    -device
> pcie-root-port,id=pcie-root-port-0,multifunction=on,bus=pcie.0,addr=0x1,chassis=1
> \
>    -device
> pcie-root-port,id=pcie-root-port-1,port=0x1,addr=0x1.0x1,bus=pcie.0,chassis=2
>
> where PCI device is hotplugged to pcie-root-port-1 with error on guest
> side:
>
>   ACPI BIOS Error (bug): Could not resolve symbol [^S0B.PCNT],
> AE_NOT_FOUND (20201113/psargs-330)
>   ACPI Error: Aborting method \_SB.PCI0.PCNT due to previous error
> (AE_NOT_FOUND) (20201113/psparse-531)
>   ACPI Error: Aborting method \_GPE._E01 due to previous error
> (AE_NOT_FOUND) (20201113/psparse-531)
>   ACPI Error: AE_NOT_FOUND, while evaluating GPE method [_E01]
> (20201113/evgpe-515)
>
> cause is that QEMU's ACPI hotplug never supported functions other then 0
> and due to bug it was generating notification entries for not described
> functions.
>
> Technically there is no reason not to describe cold-plugged bridges
> (root ports) on functions other then 0, as they similarly to bridge
> on function 0 are unpluggable.
>
> So since we need to describe multifunction devices iterate over
> fuctions as well. But describe only cold-plugged bridges[root ports]
> on functions other than 0 as well.
>
> 1)
> Fixes: 17858a169508609ca9063c544833e5a1adeb7b52 (hw/acpi/ich9: Set ACPI
> PCI hot-plug as default on Q35)
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> Reported-by: Laurent Vivier <lvivier@redhat.com>
> ---
> v2:
>   * squash 1/2 "acpi: x86: pcihp: cleanup devfn usage in
> build_append_pci_bus_devices()"
>     into the main patch
>   * drop Sxx -> Sxxx change as devfn fits into 2 digits anyway
>   * cleanup PCI_FUN/DEVFN and use func/devfn local variables instead
>   * fix typos
> ---
>  hw/i386/acpi-build.c | 44 ++++++++++++++++++++++++++++++--------------
>  1 file changed, 30 insertions(+), 14 deletions(-)
>
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 17836149fe..a33ac8b91e 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -374,7 +374,7 @@ static void build_append_pci_bus_devices(Aml
> *parent_scope, PCIBus *bus,
>      Aml *dev, *notify_method = NULL, *method;
>      QObject *bsel;
>      PCIBus *sec;
> -    int i;
> +    int devfn;
>
>      bsel = object_property_get_qobject(OBJECT(bus), ACPI_PCIHP_PROP_BSEL,
> NULL);
>      if (bsel) {
> @@ -384,23 +384,31 @@ static void build_append_pci_bus_devices(Aml
> *parent_scope, PCIBus *bus,
>          notify_method = aml_method("DVNT", 2, AML_NOTSERIALIZED);
>      }
>
> -    for (i = 0; i < ARRAY_SIZE(bus->devices); i += PCI_FUNC_MAX) {
> +    for (devfn = 0; devfn < ARRAY_SIZE(bus->devices); devfn++) {
>          DeviceClass *dc;
>          PCIDeviceClass *pc;
> -        PCIDevice *pdev = bus->devices[i];
> -        int slot = PCI_SLOT(i);
> +        PCIDevice *pdev = bus->devices[devfn];
> +        int slot = PCI_SLOT(devfn);
> +        int func = PCI_FUNC(devfn);
> +        /* ACPI spec: 1.0b: Table 6-2 _ADR Object Bus Types, PCI type */
> +        int adr = slot << 16 | func;
>          bool hotplug_enabled_dev;
>          bool bridge_in_acpi;
>          bool cold_plugged_bridge;
>
>          if (!pdev) {
> -            if (bsel) { /* add hotplug slots for non present devices */
> +            /*
> +             * add hotplug slots for non present devices.
> +             * hotplug is supported only for non-multifunction device
> +             * so generate device description only for function 0
> +             */
> +            if (bsel && !func) {
>                  if (pci_bus_is_express(bus) && slot > 0) {
>                      break;
>                  }
> -                dev = aml_device("S%.02X", PCI_DEVFN(slot, 0));
> +                dev = aml_device("S%.02X", devfn);
>                  aml_append(dev, aml_name_decl("_SUN", aml_int(slot)));
> -                aml_append(dev, aml_name_decl("_ADR", aml_int(slot <<
> 16)));
> +                aml_append(dev, aml_name_decl("_ADR", aml_int(adr)));
>                  method = aml_method("_EJ0", 1, AML_NOTSERIALIZED);
>                  aml_append(method,
>                      aml_call2("PCEJ", aml_name("BSEL"), aml_name("_SUN"))
> @@ -436,9 +444,18 @@ static void build_append_pci_bus_devices(Aml
> *parent_scope, PCIBus *bus,
>              continue;
>          }
>
> -        /* start to compose PCI slot descriptor */
> -        dev = aml_device("S%.02X", PCI_DEVFN(slot, 0));
> -        aml_append(dev, aml_name_decl("_ADR", aml_int(slot << 16)));
> +        /*
> +         * allow describing coldplugged bridges in ACPI even if they are
> not
> +         * on function 0, as they are not unpluggable, for all other
> devices
> +         * generate description only for function 0 per slot
> +         */
> +        if (func && !bridge_in_acpi) {
> +            continue;
> +        }
> +
> +        /* start to compose PCI device descriptor */
> +        dev = aml_device("S%.02X", devfn);
> +        aml_append(dev, aml_name_decl("_ADR", aml_int(adr)));
>
>          if (bsel) {
>              /*
> @@ -496,7 +513,7 @@ static void build_append_pci_bus_devices(Aml
> *parent_scope, PCIBus *bus,
>
>              build_append_pci_bus_devices(dev, sec_bus, pcihp_bridge_en);
>          }
> -        /* slot descriptor has been composed, add it into parent context
> */
> +        /* device descriptor has been composed, add it into parent
> context */
>          aml_append(parent_scope, dev);
>      }
>
> @@ -525,13 +542,12 @@ static void build_append_pci_bus_devices(Aml
> *parent_scope, PCIBus *bus,
>          /* Notify about child bus events in any case */
>          if (pcihp_bridge_en) {
>              QLIST_FOREACH(sec, &bus->child, sibling) {
> -                int32_t devfn = sec->parent_dev->devfn;
> -
>                  if (pci_bus_is_root(sec)) {
>                      continue;
>                  }
>
> -                aml_append(method, aml_name("^S%.02X.PCNT", devfn));
> +                aml_append(method, aml_name("^S%.02X.PCNT",
> +                                            sec->parent_dev->devfn));
>              }
>          }
>
> --
> 2.27.0
>
>

Thanks for fixing it!

 Reviewed-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>

Thanks,
Marcel

[-- Attachment #2: Type: text/html, Size: 8172 bytes --]

^ permalink raw reply	[flat|nested] 2+ messages in thread

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