linux-kernel - Re: [PATCH v2.2] x86/amd_node, platform/x86/amd/hsmp: Have HSMP use SMN through AMD

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Message-ID: <20241216183338.GA542682@yaz-khff2.amd.com>
Date: Mon, 16 Dec 2024 13:33:38 -0500
From: Yazen Ghannam <yazen.ghannam@....com>
To: Borislav Petkov <bp@...en8.de>
Cc: x86@...nel.org, tony.luck@...el.com, mario.limonciello@....com,
	bhelgaas@...gle.com, jdelvare@...e.com, linux@...ck-us.net,
	clemens@...isch.de, Shyam-sundar.S-k@....com, hdegoede@...hat.com,
	ilpo.jarvinen@...ux.intel.com, naveenkrishna.chatradhi@....com,
	suma.hegde@....com, linux-kernel@...r.kernel.org,
	linux-edac@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-hwmon@...r.kernel.org, platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH v2.2] x86/amd_node, platform/x86/amd/hsmp: Have HSMP use
 SMN through AMD_NODE

On Sat, Dec 14, 2024 at 11:05:07AM +0100, Borislav Petkov wrote:
> On Fri, Dec 13, 2024 at 03:22:06PM +0000, Yazen Ghannam wrote:
> > The HSMP interface is just an SMN interface with different offsets.
> > 
> > Define an HSMP wrapper in the SMN code and have the HSMP platform driver
> > use that rather than a local solution.
> > 
> > Also, remove the "root" member from AMD_NB, since there are no more
> > users of it.
> > 
> > Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
> > ---
> > 
> > Notes:
> >     Link:
> >     https://lore.kernel.org/20241212172711.1944927-1-yazen.ghannam@amd.com
> >     
> >     v2.1-v2.2:
> >     * Include <linux/build_bug.h> for static_assert()
> >     
> >     v2->v2.1:
> >     * Include static_assert() and comment for sysfs attributes.
> >     
> >     v1->v2:
> >     * Rebase on recent HSMP rework.
> > 
> >  arch/x86/include/asm/amd_nb.h         |  1 -
> >  arch/x86/include/asm/amd_node.h       |  3 +++
> >  arch/x86/kernel/amd_nb.c              |  1 -
> >  arch/x86/kernel/amd_node.c            |  9 +++++++
> >  drivers/platform/x86/amd/hsmp/Kconfig |  2 +-
> >  drivers/platform/x86/amd/hsmp/acpi.c  |  7 +++---
> >  drivers/platform/x86/amd/hsmp/hsmp.c  |  1 -
> >  drivers/platform/x86/amd/hsmp/hsmp.h  |  3 ---
> >  drivers/platform/x86/amd/hsmp/plat.c  | 36 +++++++++------------------
> >  9 files changed, 29 insertions(+), 34 deletions(-)
> 
> ld: drivers/platform/x86/amd/hsmp/plat.o: in function `amd_hsmp_pci_rdwr':
> /home/amd/kernel/linux/drivers/platform/x86/amd/hsmp/plat.c:44: undefined reference to `amd_smn_hsmp_rdwr'
> make[2]: *** [scripts/Makefile.vmlinux:77: vmlinux] Error 1
> make[1]: *** [/home/amd/bpetkov/kernel/linux/Makefile:1225: vmlinux] Error 2
> make[1]: *** Waiting for unfinished jobs....
> make: *** [Makefile:251: __sub-make] Error 2
> 
> Config attached.
>

I think the fix is this:

diff --git a/drivers/platform/x86/amd/hsmp/Kconfig b/drivers/platform/x86/amd/hsmp/Kconfig
index d6f7a62d55b5..fc90ef11a8ad 100644
--- a/drivers/platform/x86/amd/hsmp/Kconfig
+++ b/drivers/platform/x86/amd/hsmp/Kconfig
@@ -7,7 +7,6 @@ config AMD_HSMP
 	tristate
 
 menu "AMD HSMP Driver"
-	depends on AMD_NODE || COMPILE_TEST
 
 config AMD_HSMP_ACPI
 	tristate "AMD HSMP ACPI device driver"
@@ -29,6 +28,7 @@ config AMD_HSMP_ACPI
 
 config AMD_HSMP_PLAT
 	tristate "AMD HSMP platform device driver"
+	depends on AMD_NODE
 	select AMD_HSMP
 	help
 	  Host System Management Port (HSMP) interface is a mailbox interface

With all the recent rework, only AMD_HSMP_PLAT has a hard dependency on
AMD_NODE due to needing the SMN register access interface.

Various HSMP files still pull in <asm/amd_node.h>, but they just need
defines and an inline function.

It seems COMPILE_TEST is not needed, since this change allows
AMD_HSMP_ACPI to build without AMD_NODE which seems like the intent.

Thoughts from Platform/HSMP folks? I can send another revision if this
is okay.

Thanks,
Yazen