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SubjectRe: [PATCH net-next, 2/6] PCI: hv: Add a Hyper-V PCI mini driver for software backchannel interface
Date
Haiyang Zhang <haiyangz@microsoft.com> writes:

> This mini driver is a helper driver allows other drivers to
> have a common interface with the Hyper-V PCI frontend driver.
>
> Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
> ---
> MAINTAINERS | 1 +
> drivers/pci/Kconfig | 1 +
> drivers/pci/controller/Kconfig | 7 ++++
> drivers/pci/controller/Makefile | 1 +
> drivers/pci/controller/pci-hyperv-mini.c | 70 ++++++++++++++++++++++++++++++++
> drivers/pci/controller/pci-hyperv.c | 12 ++++--
> include/linux/hyperv.h | 30 ++++++++++----
> 7 files changed, 111 insertions(+), 11 deletions(-)
> create mode 100644 drivers/pci/controller/pci-hyperv-mini.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index e352550..c4962b9 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -7453,6 +7453,7 @@ F: drivers/hid/hid-hyperv.c
> F: drivers/hv/
> F: drivers/input/serio/hyperv-keyboard.c
> F: drivers/pci/controller/pci-hyperv.c
> +F: drivers/pci/controller/pci-hyperv-mini.c
> F: drivers/net/hyperv/
> F: drivers/scsi/storvsc_drv.c
> F: drivers/uio/uio_hv_generic.c
> diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
> index 2ab9240..bb852f5 100644
> --- a/drivers/pci/Kconfig
> +++ b/drivers/pci/Kconfig
> @@ -182,6 +182,7 @@ config PCI_LABEL
> config PCI_HYPERV
> tristate "Hyper-V PCI Frontend"
> depends on X86 && HYPERV && PCI_MSI && PCI_MSI_IRQ_DOMAIN && X86_64
> + select PCI_HYPERV_MINI
> help
> The PCI device frontend driver allows the kernel to import arbitrary
> PCI devices from a PCI backend to support PCI driver domains.
> diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
> index fe9f9f1..8e31cba 100644
> --- a/drivers/pci/controller/Kconfig
> +++ b/drivers/pci/controller/Kconfig
> @@ -281,5 +281,12 @@ config VMD
> To compile this driver as a module, choose M here: the
> module will be called vmd.
>
> +config PCI_HYPERV_MINI
> + tristate "Hyper-V PCI Mini"
> + depends on X86 && HYPERV && PCI_MSI && PCI_MSI_IRQ_DOMAIN && X86_64
> + help
> + The Hyper-V PCI Mini is a helper driver allows other drivers to
> + have a common interface with the Hyper-V PCI frontend driver.
> +

Out of pure curiosity, why not just export this interface from
PCI_HYPERV directly? Why do we need this stub?

> source "drivers/pci/controller/dwc/Kconfig"
> endmenu
> diff --git a/drivers/pci/controller/Makefile b/drivers/pci/controller/Makefile
> index d56a507..77e0132 100644
> --- a/drivers/pci/controller/Makefile
> +++ b/drivers/pci/controller/Makefile
> @@ -4,6 +4,7 @@ obj-$(CONFIG_PCIE_CADENCE_HOST) += pcie-cadence-host.o
> obj-$(CONFIG_PCIE_CADENCE_EP) += pcie-cadence-ep.o
> obj-$(CONFIG_PCI_FTPCI100) += pci-ftpci100.o
> obj-$(CONFIG_PCI_HYPERV) += pci-hyperv.o
> +obj-$(CONFIG_PCI_HYPERV_MINI) += pci-hyperv-mini.o
> obj-$(CONFIG_PCI_MVEBU) += pci-mvebu.o
> obj-$(CONFIG_PCI_AARDVARK) += pci-aardvark.o
> obj-$(CONFIG_PCI_TEGRA) += pci-tegra.o
> diff --git a/drivers/pci/controller/pci-hyperv-mini.c b/drivers/pci/controller/pci-hyperv-mini.c
> new file mode 100644
> index 0000000..9b6cd1c
> --- /dev/null
> +++ b/drivers/pci/controller/pci-hyperv-mini.c
> @@ -0,0 +1,70 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) Microsoft Corporation.
> + *
> + * Author:
> + * Haiyang Zhang <haiyangz@microsoft.com>
> + *
> + * This mini driver is a helper driver allows other drivers to
> + * have a common interface with the Hyper-V PCI frontend driver.
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/hyperv.h>
> +
> +struct hyperv_pci_block_ops hvpci_block_ops;
> +EXPORT_SYMBOL(hvpci_block_ops);
> +
> +int hyperv_read_cfg_blk(struct pci_dev *dev, void *buf, unsigned int buf_len,
> + unsigned int block_id, unsigned int *bytes_returned)
> +{
> + if (!hvpci_block_ops.read_block)
> + return -EOPNOTSUPP;
> +
> + return hvpci_block_ops.read_block(dev, buf, buf_len, block_id,
> + bytes_returned);
> +}
> +EXPORT_SYMBOL(hyperv_read_cfg_blk);
> +
> +int hyperv_write_cfg_blk(struct pci_dev *dev, void *buf, unsigned int len,
> + unsigned int block_id)
> +{
> + if (!hvpci_block_ops.write_block)
> + return -EOPNOTSUPP;
> +
> + return hvpci_block_ops.write_block(dev, buf, len, block_id);
> +}
> +EXPORT_SYMBOL(hyperv_write_cfg_blk);
> +
> +int hyperv_reg_block_invalidate(struct pci_dev *dev, void *context,
> + void (*block_invalidate)(void *context,
> + u64 block_mask))
> +{
> + if (!hvpci_block_ops.reg_blk_invalidate)
> + return -EOPNOTSUPP;
> +
> + return hvpci_block_ops.reg_blk_invalidate(dev, context,
> + block_invalidate);
> +}
> +EXPORT_SYMBOL(hyperv_reg_block_invalidate);
> +
> +static void __exit exit_hv_pci_mini(void)
> +{
> + pr_info("unloaded\n");
> +}
> +
> +static int __init init_hv_pci_mini(void)
> +{
> + pr_info("loaded\n");
> +
> + return 0;
> +}
> +
> +module_init(init_hv_pci_mini);
> +module_exit(exit_hv_pci_mini);
> +
> +MODULE_DESCRIPTION("Hyper-V PCI Mini");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index 57adeca..9c93ac2 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -983,7 +983,6 @@ int hv_read_config_block(struct pci_dev *pdev, void *buf, unsigned int len,
> *bytes_returned = comp_pkt.bytes_returned;
> return 0;
> }
> -EXPORT_SYMBOL(hv_read_config_block);
>
> /**
> * hv_pci_write_config_compl() - Invoked when a response packet for a write
> @@ -1070,7 +1069,6 @@ int hv_write_config_block(struct pci_dev *pdev, void *buf, unsigned int len,
>
> return 0;
> }
> -EXPORT_SYMBOL(hv_write_config_block);
>
> /**
> * hv_register_block_invalidate() - Invoked when a config block invalidation
> @@ -1101,7 +1099,6 @@ int hv_register_block_invalidate(struct pci_dev *pdev, void *context,
> return 0;
>
> }
> -EXPORT_SYMBOL(hv_register_block_invalidate);
>
> /* Interrupt management hooks */
> static void hv_int_desc_free(struct hv_pci_dev *hpdev,
> @@ -3045,10 +3042,19 @@ static int hv_pci_remove(struct hv_device *hdev)
> static void __exit exit_hv_pci_drv(void)
> {
> vmbus_driver_unregister(&hv_pci_drv);
> +
> + hvpci_block_ops.read_block = NULL;
> + hvpci_block_ops.write_block = NULL;
> + hvpci_block_ops.reg_blk_invalidate = NULL;
> }
>
> static int __init init_hv_pci_drv(void)
> {
> + /* Initialize PCI block r/w interface */
> + hvpci_block_ops.read_block = hv_read_config_block;
> + hvpci_block_ops.write_block = hv_write_config_block;
> + hvpci_block_ops.reg_blk_invalidate = hv_register_block_invalidate;
> +
> return vmbus_driver_register(&hv_pci_drv);
> }
>
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index 9d37f8c..2afe6fd 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -1579,18 +1579,32 @@ struct vmpacket_descriptor *
> pkt = hv_pkt_iter_next(channel, pkt))
>
> /*
> - * Functions for passing data between SR-IOV PF and VF drivers. The VF driver
> + * Interface for passing data between SR-IOV PF and VF drivers. The VF driver
> * sends requests to read and write blocks. Each block must be 128 bytes or
> * smaller. Optionally, the VF driver can register a callback function which
> * will be invoked when the host says that one or more of the first 64 block
> * IDs is "invalid" which means that the VF driver should reread them.
> */
> #define HV_CONFIG_BLOCK_SIZE_MAX 128
> -int hv_read_config_block(struct pci_dev *dev, void *buf, unsigned int buf_len,
> - unsigned int block_id, unsigned int *bytes_returned);
> -int hv_write_config_block(struct pci_dev *dev, void *buf, unsigned int len,
> - unsigned int block_id);
> -int hv_register_block_invalidate(struct pci_dev *dev, void *context,
> - void (*block_invalidate)(void *context,
> - u64 block_mask));
> +
> +int hyperv_read_cfg_blk(struct pci_dev *dev, void *buf, unsigned int buf_len,
> + unsigned int block_id, unsigned int *bytes_returned);
> +int hyperv_write_cfg_blk(struct pci_dev *dev, void *buf, unsigned int len,
> + unsigned int block_id);
> +int hyperv_reg_block_invalidate(struct pci_dev *dev, void *context,
> + void (*block_invalidate)(void *context,
> + u64 block_mask));
> +
> +struct hyperv_pci_block_ops {
> + int (*read_block)(struct pci_dev *dev, void *buf, unsigned int buf_len,
> + unsigned int block_id, unsigned int *bytes_returned);
> + int (*write_block)(struct pci_dev *dev, void *buf, unsigned int len,
> + unsigned int block_id);
> + int (*reg_blk_invalidate)(struct pci_dev *dev, void *context,
> + void (*block_invalidate)(void *context,
> + u64 block_mask));
> +};
> +
> +extern struct hyperv_pci_block_ops hvpci_block_ops;
> +
> #endif /* _HYPERV_H */

--
Vitaly

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