netdev - Re: [PATCH v2 02/17] psp: base PSP device support

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Message-ID: <685d5847a57d7_2de3952949b@willemb.c.googlers.com.notmuch>
Date: Thu, 26 Jun 2025 10:25:11 -0400
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Jakub Kicinski <kuba@...nel.org>, 
 Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc: Daniel Zahka <daniel.zahka@...il.com>, 
 Donald Hunter <donald.hunter@...il.com>, 
 "David S. Miller" <davem@...emloft.net>, 
 Eric Dumazet <edumazet@...gle.com>, 
 Paolo Abeni <pabeni@...hat.com>, 
 Simon Horman <horms@...nel.org>, 
 Jonathan Corbet <corbet@....net>, 
 Andrew Lunn <andrew+netdev@...n.ch>, 
 Saeed Mahameed <saeedm@...dia.com>, 
 Leon Romanovsky <leon@...nel.org>, 
 Tariq Toukan <tariqt@...dia.com>, 
 Boris Pismenny <borisp@...dia.com>, 
 Kuniyuki Iwashima <kuniyu@...gle.com>, 
 Willem de Bruijn <willemb@...gle.com>, 
 David Ahern <dsahern@...nel.org>, 
 Neal Cardwell <ncardwell@...gle.com>, 
 Patrisious Haddad <phaddad@...dia.com>, 
 Raed Salem <raeds@...dia.com>, 
 Jianbo Liu <jianbol@...dia.com>, 
 Dragos Tatulea <dtatulea@...dia.com>, 
 Rahul Rameshbabu <rrameshbabu@...dia.com>, 
 Stanislav Fomichev <sdf@...ichev.me>, 
 Toke Høiland-Jørgensen <toke@...hat.com>, 
 Alexander Lobakin <aleksander.lobakin@...el.com>, 
 Jacob Keller <jacob.e.keller@...el.com>, 
 netdev@...r.kernel.org
Subject: Re: [PATCH v2 02/17] psp: base PSP device support

Jakub Kicinski wrote:
> On Wed, 25 Jun 2025 19:55:01 -0400 Willem de Bruijn wrote:
> > > +#define PSP_SPI_KEY_ID		GENMASK(30, 0)
> > > +#define PSP_SPI_KEY_PHASE	BIT(31)
> > > +
> > > +#define PSPHDR_CRYPT_OFFSET	GENMASK(5, 0)
> > > +
> > > +#define PSPHDR_VERFL_SAMPLE	BIT(7)
> > > +#define PSPHDR_VERFL_DROP	BIT(6)
> > > +#define PSPHDR_VERFL_VERSION	GENMASK(5, 2)
> > > +#define PSPHDR_VERFL_VIRT	BIT(1)
> > > +#define PSPHDR_VERFL_ONE	BIT(0)  
> > 
> > Use bitfields in struct psphdr rather than manual bit twiddling?
> 
> Some call it manual bit twiddling, some call it the recommended kernel
> coding style? ;)

:)

Preferable over the following?

	struct psphdr {
		u8      nexthdr;
		u8      hdrlen;
		u8      crypt_offset;

		u8      sample:1;
		u8      drop:1;
		u8	version:4;
		u8	vc_present:1;
		u8	reserved:1;

		__be32  spi;
		__be64  iv;
		__be64  vc[]; /* optional */
	};

I suppose that has an endianness issue requiring
variants with __LITTLE_ENDIAN_BITFIELD and
__BIG_ENDIAN_BITFIELD.

Either way, just a thought.

> > Or else just consider just calling it flags rather than verfl
> > (which stands for version and flags?).
> 
> (Yes.)
> 
> > > +
> > > +/**
> > > + * struct psp_dev_config - PSP device configuration
> > > + * @versions: PSP versions enabled on the device
> > > + */
> > > +struct psp_dev_config {
> > > +	u32 versions;
> > > +};
> > > +
> > > +/**
> > > + * struct psp_dev - PSP device struct
> > > + * @main_netdev: original netdevice of this PSP device  
> > 
> > This makes sense with a single physical device plus optional virtual
> > (vlan, bonding, ..) devices.
> > 
> > It may also be possible for a single physical device (with single
> > device key) to present multiple PFs and/or VFs. In that case, will
> > there be multiple struct psp_dev, or will one PF be the "main".
> 
> AFAIU we have no ability to represent multi-PCIe function devices 
> in the kernel model today. So realistically I think psp_dev per
> function and then propagate the rotation events.

IDPF does support multiple "vports" (num_alloc_vports), and with that
struct net_device, from a single BDF.