Re: [RFC PATCH 04/21] PCI/IDE: Define Integrity and Data Encryption (IDE) extended capability

Jonathan Cameron
2024-08-28T14:24:36Z

On Fri, 23 Aug 2024 23:21:18 +1000
Alexey Kardashevskiy <aik@amd.com> wrote:

> PCIe 6.0 introduces the "Integrity & Data Encryption (IDE)" feature which
> adds a new capability with id=0x30.
>
> Add the new id to the list of capabilities. Add new flags from pciutils.
> Add a module with a helper to control selective IDE capability.
>
> TODO: get rid of lots of magic numbers. It is one annoying flexible
> capability to deal with.

Ah. I should read the patch description before reviewing.
It is indeed horrible.

>
> Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
Hi Alexey,

Some comments inline.

> ---
> drivers/pci/Makefile | 1 +
> include/linux/pci-ide.h | 18 ++
> include/uapi/linux/pci_regs.h | 76 +++++++-
> drivers/pci/ide.c | 186 ++++++++++++++++++++
> drivers/pci/Kconfig | 4 +
> 5 files changed, 284 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile
> index 1452e4ba7f00..034f17f9297a 100644
> --- a/drivers/pci/Makefile
> +++ b/drivers/pci/Makefile
> @@ -34,6 +34,7 @@ obj-$(CONFIG_PCI_P2PDMA) += p2pdma.o
> obj-$(CONFIG_XEN_PCIDEV_FRONTEND) += xen-pcifront.o
> obj-$(CONFIG_VGA_ARB) += vgaarb.o
> obj-$(CONFIG_PCI_DOE) += doe.o
> +obj-$(CONFIG_PCI_IDE) += ide.o
> obj-$(CONFIG_PCI_DYNAMIC_OF_NODES) += of_property.o
>
> obj-$(CONFIG_PCI_CMA) += cma.o cma.asn1.o
> diff --git a/include/linux/pci-ide.h b/include/linux/pci-ide.h
> new file mode 100644
> index 000000000000..983a8daf1199
> --- /dev/null
> +++ b/include/linux/pci-ide.h
> @@ -0,0 +1,18 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Integrity & Data Encryption (IDE)
> + * PCIe r6.0, sec 6.33 DOE
> + */
> +
> +#ifndef LINUX_PCI_IDE_H
> +#define LINUX_PCI_IDE_H
> +
> +int pci_ide_set_sel(struct pci_dev *pdev, unsigned int sel_index, unsigned int streamid,
> + bool enable, bool def, bool tee_limited, bool ide_cfg);
> +int pci_ide_set_sel_rid_assoc(struct pci_dev *pdev, unsigned int sel_index,
> + bool valid, u8 seg_base, u16 rid_base, u16 rid_limit);
> +int pci_ide_set_sel_addr_assoc(struct pci_dev *pdev, unsigned int sel_index, unsigned int blocknum,
> + bool valid, u64 base, u64 limit);
> +int pci_ide_get_sel_sta(struct pci_dev *pdev, unsigned int sel_index, u32 *status);
> +
> +#endif
> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index 0011a301b8c5..80962b07719a 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -743,7 +743,8 @@
> #define PCI_EXT_CAP_ID_PL_16GT 0x26 /* Physical Layer 16.0 GT/s */
> #define PCI_EXT_CAP_ID_PL_32GT 0x2A /* Physical Layer 32.0 GT/s */
> #define PCI_EXT_CAP_ID_DOE 0x2E /* Data Object Exchange */
> -#define PCI_EXT_CAP_ID_MAX PCI_EXT_CAP_ID_DOE
> +#define PCI_EXT_CAP_ID_IDE 0x30 /* Integrity and Data Encryption (IDE) */
> +#define PCI_EXT_CAP_ID_MAX PCI_EXT_CAP_ID_IDE
>
> #define PCI_EXT_CAP_DSN_SIZEOF 12
> #define PCI_EXT_CAP_MCAST_ENDPOINT_SIZEOF 40
> @@ -1150,9 +1151,82 @@
> #define PCI_DOE_DATA_OBJECT_DISC_RSP_3_PROTOCOL 0x00ff0000
> #define PCI_DOE_DATA_OBJECT_DISC_RSP_3_NEXT_INDEX 0xff000000
>
> +
Check for accidental white space changes. They distract from real content
so get rid of them before posting - even for an RFC.

> /* Compute Express Link (CXL r3.1, sec 8.1.5) */
> #define PCI_DVSEC_CXL_PORT 3
> #define PCI_DVSEC_CXL_PORT_CTL 0x0c
> #define PCI_DVSEC_CXL_PORT_CTL_UNMASK_SBR 0x00000001
>
> +/* Integrity and Data Encryption Extended Capability */
> +#define PCI_IDE_CAP 0x4
> +#define PCI_IDE_CAP_LINK_IDE_SUPP 0x1 /* Link IDE Stream Supported */
> +#define PCI_IDE_CAP_SELECTIVE_IDE_SUPP 0x2 /* Selective IDE Streams Supported */
> +#define PCI_IDE_CAP_FLOWTHROUGH_IDE_SUPP 0x4 /* Flow-Through IDE Stream Supported */
> +#define PCI_IDE_CAP_PARTIAL_HEADER_ENC_SUPP 0x8 /* Partial Header Encryption Supported */
> +#define PCI_IDE_CAP_AGGREGATION_SUPP 0x10 /* Aggregation Supported */
> +#define PCI_IDE_CAP_PCRC_SUPP 0x20 /* PCRC Supported */
> +#define PCI_IDE_CAP_IDE_KM_SUPP 0x40 /* IDE_KM Protocol Supported */
> +#define PCI_IDE_CAP_ALG(x) (((x) >> 8) & 0x1f) /* Supported Algorithms */
> +#define PCI_IDE_CAP_ALG_AES_GCM_256 0 /* AES-GCM 256 key size, 96b MAC */
> +#define PCI_IDE_CAP_LINK_TC_NUM(x) (((x) >> 13) & 0x7) /* Link IDE TCs */
> +#define PCI_IDE_CAP_SELECTIVE_STREAMS_NUM(x) (((x) >> 16) & 0xff) /* Selective IDE Streams */
> +#define PCI_IDE_CAP_TEE_LIMITED_SUPP 0x1000000 /* TEE-Limited Stream Supported */
> +#define PCI_IDE_CTL 0x8
> +#define PCI_IDE_CTL_FLOWTHROUGH_IDE 0x4 /* Flow-Through IDE Stream Enabled */
> +#define PCI_IDE_LINK_STREAM 0xC

> +/* Link IDE Stream block, up to PCI_IDE_CAP_LINK_TC_NUM */
These are in a fixed location, so you can define an offset macro to get to each
register.

> +/* Link IDE Stream Control Register */
...

> +/* Link IDE Stream Status Register */

> +/* Selective IDE Stream block, up to PCI_IDE_CAP_SELECTIVE_STREAMS_NUM */
> +/* Selective IDE Stream Capability Register */
> +#define PCI_IDE_SEL_CAP_BLOCKS_NUM(x) ((x) & 0xf) /*Address Association Register Blocks Number */
Space after /*

> #endif /* LINUX_PCI_REGS_H */
> diff --git a/drivers/pci/ide.c b/drivers/pci/ide.c
> new file mode 100644
> index 000000000000..dc0632e836e7
> --- /dev/null
> +++ b/drivers/pci/ide.c
> @@ -0,0 +1,186 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Integrity & Data Encryption (IDE)
> + * PCIe r6.0, sec 6.33 DOE
> + */
> +
> +#define dev_fmt(fmt) "IDE: " fmt
> +
> +#include <linux/pci.h>
> +#include <linux/pci-ide.h>
> +#include <linux/bitfield.h>
> +#include <linux/module.h>
> +
> +#define DRIVER_VERSION "0.1"
> +#define DRIVER_AUTHOR "aik@amd.com"
> +#define DRIVER_DESC "Integrity and Data Encryption driver"
> +
> +/* Returns an offset of the specific IDE stream block */
> +static u16 sel_off(struct pci_dev *pdev, unsigned int sel_index)
Prefix functions with something to indicate they are local.

ide_ or something like that.

Not obvious what sel_index parameter is. So documentation probably
needed for this function.

Also return an error, not 0 to mean error as it will be easier to read.

> +{
> + u16 offset = pci_find_next_ext_capability(pdev, 0, PCI_EXT_CAP_ID_IDE);
> + unsigned int linknum = 0, selnum = 0, i;

I'd avoid mixing cases where the value is set and where it isn't.
Better to have
unsigned int linknum = 0, selnum = 0;
unsigned int i;

Though i might as well be int.

> + u16 seloff;
> + u32 cap = 0;
> +
> + if (!offset)
> + return 0;
Not an error? That probably needs a comment.
> +
> + pci_read_config_dword(pdev, offset + PCI_IDE_CAP, &cap);
> + if (cap & PCI_IDE_CAP_SELECTIVE_IDE_SUPP)
> + selnum = PCI_IDE_CAP_SELECTIVE_STREAMS_NUM(cap) + 1;
if (!(cap & PCI_IDE_CAP_SELECTIVE_IDE_SUPP))
return -EINVAL; or whatever makes more sense.

sel_num = PCI_IDE_CAP_SELECTIVE_STREAMS_NUM(cap) + 1;
if (selnum < sel_index)
return -E...

> +
> + if (!selnum || sel_index >= selnum)
> + return 0;
> +
> + if (cap & PCI_IDE_CAP_LINK_IDE_SUPP)
> + linknum = PCI_IDE_CAP_LINK_TC_NUM(cap) + 1;
> +
> + seloff = offset + PCI_IDE_LINK_STREAM + linknum * 2 * 4;

2 and 4 have meaning. What are they? Use differences in addresses
of registers defined in header.

> + for (i = 0; i < sel_index; ++i) {
> + u32 selcap = 0;
> +
> + pci_read_config_dword(pdev, seloff, &selcap);
> +
> + /* Selective Cap+Ctrl+Sta + Addr#*8 */
> + seloff += 3 * 4 + PCI_IDE_SEL_CAP_BLOCKS_NUM(selcap) * 2 * 4;

Same here. All these offsets are in terms of real register differences,
use those and you won't need comments to explain.

> + }
> +
> + return seloff;
> +}
> +
> +static u16 sel_off_addr_block(struct pci_dev *pdev, u16 offset, unsigned int blocknum)
> +{
> + unsigned int blocks;
> + u32 selcap = 0;
> +
> + pci_read_config_dword(pdev, offset, &selcap);
> +
> + blocks = PCI_IDE_SEL_CAP_BLOCKS_NUM(selcap);
> + if (!blocks)
> + return 0;
> +
> + return offset + 3 * 4 + // Skip Cap, Ctl, Sta
> + 2 * 4 + // RID Association Register 1 and 2
Defines should exist for the registers, use the differences between them to
get these offsets.
It gets a little trickier for these as there is a variable size
field before them, but still good to do if possible.

> + blocknum * 3 * 4; // Each block is Address Association Register 1, 2, 3
> +}
> +
> +static int set_sel(struct pci_dev *pdev, unsigned int sel_index, u32 value)
> +{
> + u16 offset = sel_off(pdev, sel_index);
int offset = ide_sel_off(pdev, sel_inxed);
> + u32 status = 0;
> +
> + if (!offset)
> + return -EINVAL;
Return an error for sel_off not 0 on failure. Then pass that error on here.
if (offset < 0)
return -EINVAL;
> +
> + pci_read_config_dword(pdev, offset + 8, &status);
> + if (status & PCI_IDE_SEL_STS_RECVD_INTEGRITY_CHECK) {
> + pci_warn(pdev, "[%x] Clearing \"Received integrity check\"\n", offset + 4);
> + pci_write_config_dword(pdev, offset + 8,
> + status & ~PCI_IDE_SEL_STS_RECVD_INTEGRITY_CHECK);
> + }
> +
> + /* Selective IDE Stream Control Register */
> + pci_write_config_dword(pdev, offset + 4, value);
> + return 0;
> +}

> +
> +int pci_ide_set_sel_addr_assoc(struct pci_dev *pdev, unsigned int sel_index, unsigned int blocknum,
> + bool valid, u64 base, u64 limit)
> +{
> + u16 offset = sel_off(pdev, sel_index), offset_ab;
> + u32 a1 = PCI_IDE_SEL_ADDR_1(1, base, limit);
> + u32 a2 = PCI_IDE_SEL_ADDR_2(limit);
> + u32 a3 = PCI_IDE_SEL_ADDR_3(base);
> +
> + if (!offset)
> + return -EINVAL;
> +
> + offset_ab = sel_off_addr_block(pdev, offset, blocknum);
> + if (!offset_ab || offset_ab <= offset)

How would you get the second condition? Also, better to return
errors from these than 0 to indicate a problem.

> + return -EINVAL;
> +
> + /* IDE Address Association Register 1 */
> + pci_write_config_dword(pdev, offset_ab, a1);

Check for error error returns consistently.

> + /* IDE Address Association Register 2 */
> + pci_write_config_dword(pdev, offset_ab + 4, a2);
> + /* IDE Address Association Register 1 */
> + pci_write_config_dword(pdev, offset_ab + 8, a3);
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(pci_ide_set_sel_addr_assoc);
> +
> +int pci_ide_get_sel_sta(struct pci_dev *pdev, unsigned int sel_index, u32 *status)
> +{
> + u16 offset = sel_off(pdev, sel_index);
> + u32 s = 0;
> + int ret;
> +
> + if (!offset)
> + return -EINVAL;
With changes suggested above return the error code form sel_off.

> +
> +
> + ret = pci_read_config_dword(pdev, offset + 8, &s);
> + if (ret)
> + return ret;
> +
> + *status = s;
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(pci_ide_get_sel_sta);
> +
> +static int __init ide_init(void)
> +{
> + int ret = 0;
> +
> + pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");

Linux hasn't cared about driver versions for a long time
which is why relatively few drivers bother with them.
Why do we care here?

Also too noisy.

> + return ret;
> +}
> +
> +static void __exit ide_cleanup(void)
> +{

You don't have to have this until it has something in it.

> +}
> +
> +module_init(ide_init);
> +module_exit(ide_cleanup);
> +
> +MODULE_VERSION(DRIVER_VERSION);
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR(DRIVER_AUTHOR);
> +MODULE_DESCRIPTION(DRIVER_DESC);

With the print above gone away, just use strings here.

> diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
> index b0b14468ba5d..8e908d684c77 100644
> --- a/drivers/pci/Kconfig
> +++ b/drivers/pci/Kconfig
> @@ -137,6 +137,10 @@ config PCI_CMA
> config PCI_DOE
> bool
>
> +config PCI_IDE
> + tristate
> + default m
Don't set default. Everything defaults to off and distro's
get to turn them on.

> +
> config PCI_ECAM
> bool
>