> -----Original Message----- > From: [email protected] <[email protected]> > Sent: Friday, July 24, 2026 4:09 PM > To: Linux on Hyper-V List <[email protected]>; linux- > [email protected] > Cc: Wei Liu <[email protected]>; KY Srinivasan <[email protected]>; > Haiyang Zhang <[email protected]>; Dexuan Cui > <[email protected]>; Long Li <[email protected]>; Jonathan Corbet > <[email protected]>; Shuah Khan <[email protected]>; Lorenzo > Pieralisi <[email protected]>; Krzysztof Wilczyński > <[email protected]>; Manivannan Sadhasivam <[email protected]>; Rob > Herring <[email protected]>; Bjorn Helgaas <[email protected]>; open > list:DOCUMENTATION <[email protected]>; open list <linux- > [email protected]> > Subject: [EXTERNAL] [PATCH RFC 2/2] PCI: hv: Add vPCI device reset support > > From: Wei Liu <[email protected]> > > Hyper-V vPCI protocol version 1.5 adds a RESET_DEVICE request for projected > PCI functions. Negotiate the new protocol version and issue the request > through the vPCI VMBus channel from the PCI controller reset callback. > > Use the existing VMBus response path. Return -ENOTTY when the host > reports STATUS_NOT_SUPPORTED so PCI core may try another reset method. > > Signed-off-by: Wei Liu <[email protected]> Reviewed-by: Long Li <[email protected]> > --- > Documentation/virt/hyperv/vpci.rst | 2 +- drivers/pci/controller/pci- > hyperv.c | 61 +++++++++++++++++++++++++++++ > 2 files changed, 62 insertions(+), 1 deletion(-) > > diff --git a/Documentation/virt/hyperv/vpci.rst > b/Documentation/virt/hyperv/vpci.rst > index b65b2126ede3..6bfee7225c14 100644 > --- a/Documentation/virt/hyperv/vpci.rst > +++ b/Documentation/virt/hyperv/vpci.rst > @@ -65,7 +65,7 @@ exchange messages with the vPCI VSP for the purpose > of setting up and configuring the vPCI device in Linux. Once the device is > fully configured in Linux as a PCI device, the VMBus channel is used only if > Linux changes the vCPU to be interrupted -in the guest, or if the vPCI device > is removed from > +in the guest, or if the vPCI device is reset or removed from > the VM while the VM is running. The ongoing operation of the device > happens directly between the Linux device driver for the device and the > hardware, with VMBus and the VMBus channel diff --git > a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c > index cfc8fa403dad..d3c0fd5e1d8e 100644 > --- a/drivers/pci/controller/pci-hyperv.c > +++ b/drivers/pci/controller/pci-hyperv.c > @@ -68,6 +68,7 @@ enum pci_protocol_version_t { > PCI_PROTOCOL_VERSION_1_2 = PCI_MAKE_VERSION(1, 2), /* > RS1 */ > PCI_PROTOCOL_VERSION_1_3 = PCI_MAKE_VERSION(1, 3), /* > Vibranium */ > PCI_PROTOCOL_VERSION_1_4 = PCI_MAKE_VERSION(1, 4), /* > WS2022 */ > + PCI_PROTOCOL_VERSION_1_5 = PCI_MAKE_VERSION(1, 5), /* GE, > device reset */ > }; > > #define CPU_AFFINITY_ALL -1ULL > @@ -77,6 +78,7 @@ enum pci_protocol_version_t { > * first. > */ > static enum pci_protocol_version_t pci_protocol_versions[] = { > + PCI_PROTOCOL_VERSION_1_5, > PCI_PROTOCOL_VERSION_1_4, > PCI_PROTOCOL_VERSION_1_3, > PCI_PROTOCOL_VERSION_1_2, > @@ -90,6 +92,7 @@ static enum pci_protocol_version_t > pci_protocol_versions[] = { #define MAX_SUPPORTED_MSI_MESSAGES 0x400 > > #define STATUS_REVISION_MISMATCH 0xC0000059 > +#define STATUS_NOT_SUPPORTED 0xC00000BB > > /* space for 32bit serial number as string */ #define SLOT_NAME_SIZE 11 > @@ -136,6 +139,7 @@ enum pci_message_type { > PCI_BUS_RELATIONS2 = PCI_MESSAGE_BASE + 0x19, > PCI_RESOURCES_ASSIGNED3 = PCI_MESSAGE_BASE + 0x1A, > PCI_CREATE_INTERRUPT_MESSAGE3 = PCI_MESSAGE_BASE + 0x1B, > + PCI_RESET_DEVICE = PCI_MESSAGE_BASE + 0x1C, > PCI_MESSAGE_MAXIMUM > }; > > @@ -1397,10 +1401,66 @@ static int hv_pcifront_write_config(struct pci_bus > *bus, unsigned int devfn, > return PCIBIOS_SUCCESSFUL; > } > > +static int hv_pcifront_reset(struct pci_dev *pdev, bool probe) { > + struct hv_pcibus_device *hbus = > + container_of(pdev->bus->sysdata, struct hv_pcibus_device, > sysdata); > + struct pci_child_message reset = {}; > + struct hv_pci_compl comp_pkt; > + struct pci_packet pkt = { > + .completion_func = hv_pci_generic_compl, > + .compl_ctxt = &comp_pkt, > + }; > + enum hv_pcibus_state state; > + int ret; > + > + /* Device reset was added in vPCI protocol version 1.5. */ > + if (hbus->protocol_version < PCI_PROTOCOL_VERSION_1_5) > + return -ENOTTY; > + > + /* Hyper-V exposes projected functions directly on the root bus. */ > + if (!pci_is_root_bus(pdev->bus)) > + return -ENOTTY; > + > + if (probe) > + return 0; > + > + /* Do not take state_lock: eject holds it while removing/locking pdev. > */ > + state = READ_ONCE(hbus->state); > + if (state != hv_pcibus_probed && state != hv_pcibus_installed) > + return -ENODEV; > + > + init_completion(&comp_pkt.host_event); > + reset.message_type.type = PCI_RESET_DEVICE; > + reset.wslot.slot = devfn_to_wslot(pdev->devfn); > + > + ret = vmbus_sendpacket(hbus->hdev->channel, &reset, sizeof(reset), > + (unsigned long)&pkt, VM_PKT_DATA_INBAND, > + > VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED); > + if (ret) > + return ret; > + > + ret = wait_for_response(hbus->hdev, &comp_pkt.host_event); > + if (ret) > + return ret; > + > + if (comp_pkt.completion_status == STATUS_NOT_SUPPORTED) > + return -ENOTTY; > + > + if (comp_pkt.completion_status) { > + pci_err(pdev, "Hyper-V device reset failed: %#x\n", > + comp_pkt.completion_status); > + return -EIO; > + } > + > + return 0; > +} > + > /* PCIe operations */ > static struct pci_ops hv_pcifront_ops = { > .read = hv_pcifront_read_config, > .write = hv_pcifront_write_config, > + .reset = hv_pcifront_reset, > }; > > /* > @@ -1996,6 +2056,7 @@ static void hv_compose_msi_msg(struct irq_data > *data, struct msi_msg *msg) > break; > > case PCI_PROTOCOL_VERSION_1_4: > + case PCI_PROTOCOL_VERSION_1_5: > size = hv_compose_msi_req_v3(&ctxt.int_pkts.v3, > cpu, > hpdev->desc.win_slot.slot, > -- > 2.53.0
