RE: [PATCH net-next, 2/6] PCI: hv: Add a Hyper-V PCI mini driver for software backchannel interface

2019-08-16 Thread Haiyang Zhang 



> -Original Message-
> From: Vitaly Kuznetsov 
> Sent: Friday, August 16, 2019 12:16 PM
> To: Haiyang Zhang 
> Cc: KY Srinivasan ; Stephen Hemminger
> ; linux-kernel@vger.kernel.org;
> sas...@kernel.org; da...@davemloft.net; sae...@mellanox.com;
> l...@kernel.org; era...@mellanox.com; lorenzo.pieral...@arm.com;
> bhelg...@google.com; linux-...@vger.kernel.org; linux-
> hyp...@vger.kernel.org; net...@vger.kernel.org
> Subject: RE: [PATCH net-next, 2/6] PCI: hv: Add a Hyper-V PCI mini driver for
> software backchannel interface
> 
> Haiyang Zhang  writes:
> 
> >
> > The pci_hyperv can only be loaded on VMs on Hyper-V and Azure. Other
> > drivers like MLX5e will have symbolic dependency of pci_hyperv if they
> > use functions exported by pci_hyperv. This dependency will cause other
> > drivers fail to load on other platforms, like VMs on KVM. So we
> > created this mini driver, which can be loaded on any platforms to
> > provide the symbolic dependency.
> 
> (/me wondering is there a nicer way around this, by using __weak or
> something like that...)
> 
> In case this stub is the best solution I'd suggest to rename it to something 
> like
> PCI_HYPERV_INTERFACE to make it clear it is not a separate driver (_MINI
> makes me think so).

Thanks! I will consider those options.

RE: [PATCH net-next, 2/6] PCI: hv: Add a Hyper-V PCI mini driver for software backchannel interface

2019-08-16 Thread Vitaly Kuznetsov 
Haiyang Zhang  writes:

>
> The pci_hyperv can only be loaded on VMs on Hyper-V and Azure. Other 
> drivers like MLX5e will have symbolic dependency of pci_hyperv if they 
> use functions exported by pci_hyperv. This dependency will cause other 
> drivers fail to load on other platforms, like VMs on KVM. So we created 
> this mini driver, which can be loaded on any platforms to provide the 
> symbolic dependency.

(/me wondering is there a nicer way around this, by using __weak or
something like that...)

In case this stub is the best solution I'd suggest to rename it to
something like PCI_HYPERV_INTERFACE to make it clear it is not a
separate driver (_MINI makes me think so).

-- 
Vitaly

RE: [PATCH net-next, 2/6] PCI: hv: Add a Hyper-V PCI mini driver for software backchannel interface

2019-08-16 Thread Haiyang Zhang 



> -Original Message-
> From: Vitaly Kuznetsov 
> Sent: Friday, August 16, 2019 8:28 AM
> To: Haiyang Zhang ; sas...@kernel.org;
> da...@davemloft.net; sae...@mellanox.com; l...@kernel.org;
> era...@mellanox.com; lorenzo.pieral...@arm.com; bhelg...@google.com;
> linux-...@vger.kernel.org; linux-hyp...@vger.kernel.org;
> net...@vger.kernel.org
> Cc: Haiyang Zhang ; KY Srinivasan
> ; Stephen Hemminger ;
> linux-kernel@vger.kernel.org
> Subject: Re: [PATCH net-next, 2/6] PCI: hv: Add a Hyper-V PCI mini driver for
> software backchannel interface
> 
> Haiyang Zhang  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 
> > Signed-off-by: Saeed Mahameed 
> > ---
> >  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?

The pci_hyperv can only be loaded on VMs on Hyper-V and Azure. Other 
drivers like MLX5e will have symbolic dependency of pci_hyperv if they 
use functions exported by pci_hyperv. This dependency will cause other 
drivers fail to load on other platforms, like VMs on KVM. So we created 
this mini driver, which can be loaded on any platforms to provide the 
symbolic dependency.

Thanks,
- Haiyang

Re: [PATCH net-next, 2/6] PCI: hv: Add a Hyper-V PCI mini driver for software backchannel interface

2019-08-16 Thread Vitaly Kuznetsov 
Haiyang Zhang  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 
> Signed-off-by: Saeed Mahameed 
> ---
>  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 000..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 
> + *
> + * 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 
> +#include 
> +#include 
> +
> +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_in

[PATCH net-next, 2/6] PCI: hv: Add a Hyper-V PCI mini driver for software backchannel interface

2019-08-14 Thread Haiyang Zhang 
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 
Signed-off-by: Saeed Mahameed 
---
 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.
+
 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 000..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 
+ *
+ * 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 
+#include 
+#include 
+
+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("H