The current implementers of ARI are all SR-IOV devices. The ARI next
function number field is undefined for VF. The PF should end the linked
list formed with the field by specifying 0.

Fixes: 2503461691 ("pcie: Add some SR/IOV API documentation in docs/pcie_sriov.txt")
Fixes: 44c2c09488 ("hw/nvme: Add support for SR-IOV")
Fixes: 3a977deebe ("Intrdocue igb device emulation")
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 include/hw/pci/pci.h | 2 ++
 hw/core/machine.c    | 1 +
 hw/pci/pci.c         | 2 ++
 hw/pci/pcie.c        | 2 +-
 4 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index e6d0574a29..9c5b5eb206 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -209,6 +209,8 @@ enum {
     QEMU_PCIE_CAP_CXL = (1 << QEMU_PCIE_CXL_BITNR),
 #define QEMU_PCIE_ERR_UNC_MASK_BITNR 11
     QEMU_PCIE_ERR_UNC_MASK = (1 << QEMU_PCIE_ERR_UNC_MASK_BITNR),
+#define QEMU_PCIE_ARI_NEXTFN_1_BITNR 12
+    QEMU_PCIE_ARI_NEXTFN_1 = (1 << QEMU_PCIE_ARI_NEXTFN_1_BITNR),
 };
 
 typedef struct PCIINTxRoute {
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 46f8f9a2b0..f0d35c6401 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -41,6 +41,7 @@
 
 GlobalProperty hw_compat_8_0[] = {
     { "migration", "multifd-flush-after-each-section", "on"},
+    { TYPE_PCI_DEVICE, "x-pcie-ari-nextfn-1", "on" },
 };
 const size_t hw_compat_8_0_len = G_N_ELEMENTS(hw_compat_8_0);
 
diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index e2eb4c3b4a..f2ce1dbfd0 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -82,6 +82,8 @@ static Property pci_props[] = {
     DEFINE_PROP_UINT32("acpi-index",  PCIDevice, acpi_index, 0),
     DEFINE_PROP_BIT("x-pcie-err-unc-mask", PCIDevice, cap_present,
                     QEMU_PCIE_ERR_UNC_MASK_BITNR, true),
+    DEFINE_PROP_BIT("x-pcie-ari-nextfn-1", PCIDevice, cap_present,
+                    QEMU_PCIE_ARI_NEXTFN_1_BITNR, true),
     DEFINE_PROP_END_OF_LIST()
 };
 
diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
index 9a3f6430e8..cf09e03a10 100644
--- a/hw/pci/pcie.c
+++ b/hw/pci/pcie.c
@@ -1030,7 +1030,7 @@ void pcie_sync_bridge_lnk(PCIDevice *bridge_dev)
 /* ARI */
 void pcie_ari_init(PCIDevice *dev, uint16_t offset)
 {
-    uint16_t nextfn = 1;
+    uint16_t nextfn = dev->cap_present & QEMU_PCIE_ARI_NEXTFN_1 ? 1 : 0;
 
     pcie_add_capability(dev, PCI_EXT_CAP_ID_ARI, PCI_ARI_VER,
                         offset, PCI_ARI_SIZEOF);
-- 
2.41.0

On Sun,  2 Jul 2023 21:02:27 +0900
Akihiko Odaki <akihiko.odaki@daynix.com> wrote:

> The current implementers of ARI are all SR-IOV devices. The ARI next
> function number field is undefined for VF. The PF should end the linked
> list formed with the field by specifying 0.

this should also describe compat behavior changes.


> Fixes: 2503461691 ("pcie: Add some SR/IOV API documentation in docs/pcie_sriov.txt")
> Fixes: 44c2c09488 ("hw/nvme: Add support for SR-IOV")
> Fixes: 3a977deebe ("Intrdocue igb device emulation")
> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> ---
>  include/hw/pci/pci.h | 2 ++
>  hw/core/machine.c    | 1 +
>  hw/pci/pci.c         | 2 ++
>  hw/pci/pcie.c        | 2 +-
>  4 files changed, 6 insertions(+), 1 deletion(-)
> 

>  GlobalProperty hw_compat_8_0[] = {
>      { "migration", "multifd-flush-after-each-section", "on"},
> +    { TYPE_PCI_DEVICE, "x-pcie-ari-nextfn-1", "on" },
>  };

[...]

> +    DEFINE_PROP_BIT("x-pcie-ari-nextfn-1", PCIDevice, cap_present,
> +                    QEMU_PCIE_ARI_NEXTFN_1_BITNR, true),

now, I'm confused a bit. So above line says that default
x-pcie-ari-nextfn-1=on

then compat also sets it to 'on', so question is why do
we have compat entry at all?
If default state doesn't change why do we need involve compat
machinery and add "x-pcie-ari-nextfn-1" property?

>      DEFINE_PROP_END_OF_LIST()
>  };
>  
> diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> index 9a3f6430e8..cf09e03a10 100644
> --- a/hw/pci/pcie.c
> +++ b/hw/pci/pcie.c
> @@ -1030,7 +1030,7 @@ void pcie_sync_bridge_lnk(PCIDevice *bridge_dev)
>  /* ARI */
>  void pcie_ari_init(PCIDevice *dev, uint16_t offset)
>  {
> -    uint16_t nextfn = 1;
> +    uint16_t nextfn = dev->cap_present & QEMU_PCIE_ARI_NEXTFN_1 ? 1 : 0;
>  
>      pcie_add_capability(dev, PCI_EXT_CAP_ID_ARI, PCI_ARI_VER,
>                          offset, PCI_ARI_SIZEOF);