Re: [PATCH v3 1/1] arm64: rsi: Add automatic arm-cca-guest module loading

[Jeremy Linton]

Hi,

On 12/7/24 10:38 PM, Itaru Kitayama wrote:
> Hi Jeremy,
>
> On Fri, Dec 06, 2024 at 07:21:28PM -0600, Jeremy Linton wrote:
> > The TSM module provides guest identification and attestation when a
> > guest runs in CCA mode. By creating a dummy platform device, let's
>
> Perhaps could you spell out like; a guest runs in the Realm state?

Thanks for looking at this.

I thought that was evident from the rest of the commits here, but sure.

Thanks again.


> Thanks,
> Itaru.
>   
> > ensure the module is automatically loaded. The udev daemon loads the
> > TSM module after it receives a device addition event. Once that
> > happens, it can be used earlier in the boot process to decrypt the
> > rootfs.
> >
> > Signed-off-by: Jeremy Linton <jeremy.linton@xxxxxxx>
> > Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>
> > ---
> >   arch/arm64/include/asm/rsi.h                    |  2 ++
> >   arch/arm64/kernel/rsi.c                         | 15 +++++++++++++++
> >   drivers/virt/coco/arm-cca-guest/arm-cca-guest.c |  8 ++++++++
> >   3 files changed, 25 insertions(+)
> >
> > diff --git a/arch/arm64/include/asm/rsi.h b/arch/arm64/include/asm/rsi.h
> > index 188cbb9b23f5..b42aeac05340 100644
> > --- a/arch/arm64/include/asm/rsi.h
> > +++ b/arch/arm64/include/asm/rsi.h
> > @@ -10,6 +10,8 @@
> >   #include <linux/jump_label.h>
> >   #include <asm/rsi_cmds.h>
> >   
> > +#define RSI_PDEV_NAME "arm-cca-dev"
> > +
> >   DECLARE_STATIC_KEY_FALSE(rsi_present);
> >   
> >   void __init arm64_rsi_init(void);
> > diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
> > index 3031f25c32ef..5434e5496ac2 100644
> > --- a/arch/arm64/kernel/rsi.c
> > +++ b/arch/arm64/kernel/rsi.c
> > @@ -8,6 +8,7 @@
> >   #include <linux/psci.h>
> >   #include <linux/swiotlb.h>
> >   #include <linux/cc_platform.h>
> > +#include <linux/platform_device.h>
> >   
> >   #include <asm/io.h>
> >   #include <asm/mem_encrypt.h>
> > @@ -140,3 +141,17 @@ void __init arm64_rsi_init(void)
> >   	static_branch_enable(&rsi_present);
> >   }
> >   
> > +static struct platform_device rsi_dev = {
> > +	.name = RSI_PDEV_NAME,
> > +	.id = PLATFORM_DEVID_NONE
> > +};
> > +
> > +static int __init rsi_init(void)
> > +{
> > +	if (is_realm_world() &&
> > +	    platform_device_register(&rsi_dev))
> > +		pr_err("failed to register rsi platform device\n");
> > +	return 0;
> > +}
> > +
> > +arch_initcall(rsi_init)
> > diff --git a/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c b/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
> > index 488153879ec9..87f162736b2e 100644
> > --- a/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
> > +++ b/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
> > @@ -6,6 +6,7 @@
> >   #include <linux/arm-smccc.h>
> >   #include <linux/cc_platform.h>
> >   #include <linux/kernel.h>
> > +#include <linux/mod_devicetable.h>
> >   #include <linux/module.h>
> >   #include <linux/smp.h>
> >   #include <linux/tsm.h>
> > @@ -219,6 +220,13 @@ static void __exit arm_cca_guest_exit(void)
> >   }
> >   module_exit(arm_cca_guest_exit);
> >   
> > +/* modalias, so userspace can autoload this module when RSI is available */
> > +static const struct platform_device_id arm_cca_match[] __maybe_unused = {
> > +	{ RSI_PDEV_NAME, 0},
> > +	{ }
> > +};
> > +
> > +MODULE_DEVICE_TABLE(platform, arm_cca_match);
> >   MODULE_AUTHOR("Sami Mujawar <sami.mujawar@xxxxxxx>");
> >   MODULE_DESCRIPTION("Arm CCA Guest TSM Driver");
> >   MODULE_LICENSE("GPL");
> > --
> > 2.46.0